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MISCELLANEOUS PAPER S71-17
EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS
Report 2
ANALYSIS OF RESPONSE O F RIFLE.GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR
DETONATION bv
J. E. Ahlberg, J. Fowler, L W. Heller ........ ........-..... ..........-..- ...... *- , .... . ..- ->-w-J- * -: -
. .
June 1972
s~omsored by Office, Chief of Engineers, U. S. Army
Conducted by U. S. A m y Engineer Waterways Experiment Station
Soils and Pavements Laboratory
Vicksburg, Mississippi
APPROVED FOR WBLlC RELEASE: DISTRIBUTION UNLIMITED
L i s t o f Associated Reports
Previous reports under Engineering Study 540 are:
"A Comparative Summary o f Current Earth Dam Analysis Methods for Earthquake Response," issued by Office, Chief o f Engineers, as Inclosure 1 to Engineer
, . , - . Jeihnical Let ter No. 11 10-2-77, 9 December 1969. - 0 1 . \ , -
v , - . r i '. ../. +c_Eaithquake Studies for Earth and Rock- f i l l Dams," issued by Office, Chief o f %A P , . a 3 Engineers, as Engineer Technical Le t t e r NO. 11 10-2-79, 12 January 1970.
"Motion o f R i f l e Gap Dam, Rif le, Colorado; Proiect Rul ison Underground Nuclear Detonation," published by the Waterways Experiment Station as Miscellaneous Paper 5-70-1, January 1970.
"Earthquake Resistance of Earth and Rock- f i l l Dams; Report 1, Discuss ions by Professors H. B. Seed and R. V. Whitman," published by the Waterways Experi- ment Station as Miscellaneous Paper 5-7 1-17, h a y 1971.
Destroy th i s report when no longer needed. Do not return it to the originator.
The findings in th is report are no t to be construed as an o f f i c i a l Department of the Army pos i t i on unless so designated
by other author ized documents.
MISCELLANEOUS PAPER S-71-17
EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS
Report 2
ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR
DETONATION
by
J. E. Ahlberg, J. Fowler, L W. Heller
June 1972
Sponsored by Office, Chief of Engineers, U. S. Army
Conducted by U. S. Army Engineer Waterways Experiment Station
Soils and Pavements Laboratory
Vicksburg, Mississippi
A R Y V - Y R C V I C K S O U I Q . YtSm.
APPROVED FOR PUBUC RELEASE; DISTRIBUTION UNLIMITED
T H E CONTENTS OF T H I S REPORT ARE NOT T O BE
USED FOR ADVERTISING, P U B L I C A T I O N , OR
PROMOTIONAL PURPOSES. C I T A T I O N O F TRADE .
NAMES DOES NOT CONSTITUTE AN O F F I C I A L EN-
DORSEMENT OR APPROVAL O F T H E USE OF SUCH
COMMERCIAL PRODUCTS.
iii
FOREWORD
This repor t p resen ts an ana lys i s o f t he motion of R i f l e Gap Dam
during t h e underground nuclear explosion, ProJect RULISON. This analy-.
s i s was made f o r t he Off ice , Chief of Engineers ( O C E ) , by t h e U. S. A r v
Engineer Waterways Experiment S t a t i o n (WES) dur ing f i - s ca l year 1971
under Engineering Study 540, " ~ a r t h q u a k e Resistance of Earth and Rock-
f i l l D a m s . "
Engineers of . t h e S o i l s and Pavements Laboratory, WES, a c t i v e l y en-
gaged i n d i r e c t i n g t h e work .and r e p o r t p repara t ion were Messrs . S . J.
Johnson, R . W . Cunny, J. Fowler, D r . L. W . Hel ler , 1 L T J. E. Ahlberg,
and SP5 W. C . Moss. The work was under t h e genera l supervis ion of
M r . J. P. Sale, Chief, S o i l s and Pavements Laboratory. This r e p o r t was
prepared by 1LT Ahlberg with minor cont r ibu t ions by M r . Fowler and
D r . Heller . Director of WES during t h e ana lys i s and t h e prepara t ion of t h i s
report was COL Ernest D . Peixot to , CE, and Technical Director was
M r . F. R . Brown.
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CONTENTS
Page
FOREWORD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
CONVERSION FACTORS, B R I T I S H TO M E T R I C U N I T S O F MEASUREMENT. . . . i x
P A R T I -. INTRODUCTION . . .. . . . . . . . . . . . . . . . . . . . 1
PART I1 : F I E L D OBSERVATIONS. . . . . . . . . . . . . . . . . . . . 3
P A R T I1 I : MATERIAL P R O P E R T I E S . . . . . . . . . . . . . . . . . . 5
P A R T IV : CALCULATIONS. . . . . . . . . . . . . . . . . . . . . . 8
G e n e r a l . . . . . . . . . . . . . . . . . . . . . . . . . . O n e - D i m e n s i o n a l A n a l y s e s of Foundation. . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s e s of E m b a n k m e n t a n d Foundation . . .
P A R T V: COMPARISONS OF OBSERVED AND CALCULATED R E S P O N S E S . . . . 11
M e t h o d . . . . . . . . . . . . . . . . . . . . . . . . . . . O n e - D i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s i s ' . . . . . . . . . . . . . . . . . .
PART V I : D I S C U S S I O N . . . . . . . . . . . . . . . . . . . . . . . o n e - ~ i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . . T w o - D i m e n s i o n a l A n a l y s i s . . . . . . . . . . . . . . . . . .
PART V I I : CONCLUSIONS. . . . . . . . . . . . . . . . . . . . . . L I T E R A T U R E C I T E D . . . . . . . . . . . . . . . . . . . . . . . . . T A B L E S 1-4
P L A T E S 1-40
A P P E N D I X A: OBSERVED MOTIONS
P L A T E S A1-A12
A P P E N D I X B: ACCEIXRATION R E S P O N S E S P E C T R A FROM ONE-DIMENSIONAL A N A L Y S I S
P L A T E S ~ 1 - B 6
A P P E N D I X C: ACCELERATION R E S P O N S E S P E C T R A FROM TWO-DIMENSIONAL A N A L Y S I S
P L A T E S ~ 1 - C 8
A P P E N D I X D: S E I S M I C F I E L D STUDY
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. .
CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT
~ r i t i s h u n i t s o f measurement u s e d i n t h i s r e p o r t c a n be c o n v e r t e d t o
metr ic u n i t s as f o l l o w s :
Mul t ip ly By To Ob ta in
inches 2.54 c e n t i m e t e r s
f e e t
miles (u. S. s t a t u t e )
' pounds
pounds p e r squa re i n c h ,
k ips per square f o o t
pounds pe r cub ic f o o t
. inches per second
f e e t pe r second
me te r s
. k i l o m e t e r s
k i l o g r a m s
newtons p e r s q u a r e c e n t i m e t e r
k i l o n e w t ons p e r s q u a r e meter
k i l o g r a m s p e r c u b i c me te r
c e n t i m e t e r s p e r second
me te r s p e r seco'nd
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SUMMARY
The motion of R i f l e Gap D a m w a s measured i n September 1969 dur ing the Pro jec t 'RULISON underground nuc lear explosion. The observed re- sponse was then compared with t h e response computed i n a mathematical model. Observed and computed responses were s i m i l a r . From t h i s study it appears t h a t the mathematical models used a re app l i cab l e t o t h e de- sign and ana lys i s of s o i l s t r u c t u r e s , a t l e a s t f o r ground motion inten- s i t i e s comparable t o those observed a t R i f l e Gap Dam.
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6 EARTHQUAKE RESISTANCE OF EARTH AND ROCK-FILL DAMS
ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT
RULISON UNDERGROUND NUCLEAR DETONATION
PART I : INTRODUCTION
1. The U. S. A r m y Engineer Waterways Experiment S t a t i o n (WES) was
requested by the Off ice , Chief of Engineers (OCE) , t o measure and t o an-
a lyze t he response of R i f l e Gap Dam t o ground motions generated by the
P ro j ec t RULISON detonation because it was thought t h a t t he se motions
would be s imi l a r t o those generated by earthquakes. The ob j ec t i ve of
t h i s study was t o determine t h e a p p l i c a b i l i t y of seismic design proce-
dures i n designing Corps of Engineers ( C E ) e a r t h and r o c k - f i l l dams t o
withstand earthquake loadings .
2. Pro jec t RULISON, p a r t of t he PLOWSHARE program of t h e Atomic
Energy Commission ( A E C ) , was one o f a s e r i e s of detonat ions f o r i nves t i -
ga t ing s t imulat ion of t h e production of n a t u r a l gas by t h e use of nu-
c l e a r explosives. The Aus t r a l O i l Company conducted t h i s experiment as
a p r iva t e commercial venture with t h e a s s i s t a n c e o f t h e AEC, which was
responsible f o r sa fe ty and t h e detonat ion of t h e nuclear device.
3. The WES instrumented R i f l e Gap Dam w i t h t h e cooperation o f the
owner, the Bureau of Reclamation (BU Rec). Other dams instrumented fo r
ground motion measurements dur ing P r o j e c t RULISON were Harvey Gap D a m ,
instrumented by the National Ocean Survey and analyzed by the Environ-
mental Research Corporation f o r t h e AEC , and Vega Dam, instrumented and
analyzed by t h e Bu Rec. The a n a l y s i s o f R i f l e Gap Dam includes an as-
sessment of t h e geology and e l a s t i c p r o p e r t i e s of t h e s i t e and the dam,
ca l cu l a t i ons of the expected su r f ace motions using ava i l ab l e procedures,
and a comparison of ca l cu l a t ed responses of t h e dam with measured r e -
sponses r e s u l t i n g from P r o j e c t RULISON.
4. Ground zero ( G Z ) f o r Pro jec t RULISON was loca ted southwest of
R i f l e , Colorado, a t a depth of 8442.5 ft.* The nuc lear device was deto-
nated at 3:00 p.m. MST, 1 0 Septeniber 1969, and had a design y i e l d of
40 k t .
5 . R i f l e Gap Dam,. an e a r t h - f i l l s t r u c t u r e , w a s completed i n 1966
and i s loca t ed north of R i f l e , Colorado, 1 8 . 5 miles from RULISON GZ (see
p l a t e .l) . Spec i f ica t ions f o r t he dam a r e presen ted i n r e f e r ence 1. The
dam has a c r e s t l eng th of 1500 f%, a maximum base width o f 800 f t , and a
maximum he igh t of 120 ft. The dam c o n s i s t s o f a mixture o f c l a y , s i l t ,
sand, g r ave l , and cobbles. A c ro s s s e c t i o n i s shown i n p l a t e 2 . The
r e s e r v o i r l e v e l was 41 ft below t h e c r e s t du r ing P ro j ec t RULISON. Two
Bu Rec bor ings (see bo r ing logs i n p l a t e 3 and l o c a t i o n s i n p l a t e 4 ) in-
d i c a t e t h a t t h e foundation mater ia l s are a l l u v i a l s o i l s cons i s t i ng of
in terbedded c lays , s i l t s , sands, and grave ls t o depths g r e a t e r than
100 f t . Bedrock was not reached i n t he se bor ings . A~ assumed p r o f i l e
of t h e foundation s o i l s i s shown i n p l a t e 5 . The method used t o produce,
t h e assumed p r o f i l e i s d i scussed i n paragraph 11.
* A t a b l e o f f a c t o r s f o r conver t ing B r i t i s h u n i t s o f measurement t o metr ic u n i t s i s p resen ted on page i x .
r : , PART 11: FIELD OBSERVATIONS
6 . The observed motions o f R i f l e Gap D a m during Pro jec t RULISON
are repor ted i n r e f e r ence 2. The ins t ruments used fo r t h e measurements
cons i s t ed of p a r t i c l e v e l o c i t y t r an sduce r s (PVT) and p a r t i c l e acce le ra -
t i o n t ransducers (PAT) , and t h e measurements were recorded by o .sc i l lo-
graphs and t a p e r eco rde r s . The l o c a t i o n s o f t h i s equipment are shown i n
p l a t e 4, and a l ist of equipment i s given i n t a b l e 1 along wi th peak ob-
served motions. H i s t o r i e s o f t h e f i r s t 6 sec ' o f observed motion and re-
sponse s p e c t r a a r e p resen ted i n Appendix A f o r v e r t i c a l and r a d i a l (nor-
m a l t o c r e s t o f dam) components o f motion. Transverse ( p a r a l l e l t o
c r e s t o f dam) motions are r epo r t ed by ~ o w l e r , ' bu t a r e not analyzed
he r e in .
7. There i s e x c e l l e n t agreement between t h e ve loc i ty h i s t o r i e s
observed a t l o c a t i o n 6 ( p l a t e ~ l l ) and t hose ca lcu la ted a t l o c a t i o n 5
( p l a t e s A9 and A10) by t h e i n t e g r a t i o n of t h e acce le ra t ion h i s t o r i e s .
Comparison o f t h e c a l c u l a t e d v e i o c i t y h i s t o r i e s a t loca t ion 1 ( ~ l a t e s A 1
a n d ~ 2 ) i n t h e r a d i a l and v e r t i c a l d i r e c t i o n s with those observed at lo-
c a t i o n 7 (plate A12) i n d i c a t e s remarkably good agreement, even though
l o c a t i o n s 1 and 7 were approximately 200 ft a p a r t along t h e c r e s t o f t h e
dam. However, r a d i a l components o f l o c a t i o n s 1 and 7 do i nd i ca t e a con-
s i d e r a b l e phase s h i f t .
8. Location 4 w a s i n t h e g a t e chamber, loca ted i n t h e l e f t 'abut-
ment of t h e dam. The motion observed a t t h i s loca t ion i s assumed t o be
r e p r e s e n t a t i v e of bedrock motion i n t h e v a l l e y , and motions f o r t h e
f i r s t 6 s ec were used f o r i npu t i n t h e a n a l y s e s , described l a t e r .
9 . The Bu Rec took p r e sho t and pos t sho t survey readings from se t -
t lement markers on t h e dam and found t h a t no permanent displacements oc- '
cur red as a result of P r o j e c t RULISON.
0 The shea r wave v e l o c i t i e s of t h e mate r ia l s i n t he foundat ion
and embankment were de te r rdned dur ing a WES seismic f i e l d i n v e s t i g a t i o n
( ~ ~ ~ e n d i x D ) . P l a t e 6 shows t h e shea r wave ve loc i ty a s a func t ion o f . .. depth f o r t h e foundat ion p r o f i l e ob ta ined from t h e surface v ib r a to ry
tes t da t a , and shea r wave v e l o c i t i e s ob t a ined from t h e Rayleigh wave
!
dispers ion da ta a re shown in plate 7. Curro ( ~ p p e n d i x D) suggested t h a t
the' v ib ra to ry shear wave velocity data be used as a lower bound and the
maximum Rayleigh wave veloci ty data be. used as an upper bound f o r t h e
mater ia l property descr ipt ion.
where
G = shear modulus
v = shear wave v e l o c i t y S
P = mass dens i ty
These moduli a re compared i n p l a t e 8 with t h e shear moduli computed from
Hardin ' s equat ion : 3
where
G -4
= shear modulus ( a t low s t r a i n amplitudes , i. e. c0.25 x 10 max
percent ), ' p s i
e = void r a t i o
OCR = overconsol idat ion r a t i o (1.0 assumed)
k = va r i ab l e t h a t i s a func t ion o f t he p l a s t i c i t y index
, . PART 111: MATERIAL PROPERTIES
11. The foundation shea r wave ve loc i ty p r o f i l e s ( ~ p p e n d i x D ) and
Bu Rec bor ings DH21 and DH22 ( p l a t e 3) were combined t o produce t h e as-
sumed foundation p r o f i l e shown i n p l a t e 5. This was accomplished with
some d i f f i c u l t y due t o t he he te rogene i ty of t he se s o i l s , which i s typ i -
c a l of a l l u v i a l depos i t s . Location 5 w i l l be used as t h e l o c a t i o n f o r
which t h e observed and c a l c u l a t e d responses of t h e foundation a re com-
pared. However, no borings were made a t t h i s l o c a t i o n and bor ings DH21
and DH22 a r e over 500 f t and 400 f t away, respec t ive ly . Seismic mea-
' surements were made over a considerable a r e a a t t h e downstream t o e of
t h e dam. ( ~ p p e n d i x D ) . 12. The shear moduli were determined from t h e shear wave v e l o c i t y
d a t a using t h e fol lowing equat ion:
2 G = v s p
^ _ _ _ _ _ _ _ _ . _ _ _ . _ _ . _ . _ _ _ - . _ . - . _ __.. - . _-- - -. - . .- - - . . - - - ---.--.-- - - -.-- --.- .. --- ' - - - - - & - - A A_ - - - A. - A. L - &
' a = mean p r i n c i p a l e f f e c t i v e s t r e s s , p s i ( ho r i zon ta l normal 0
s t r e s s e s were assumed e q u a l )
The shear moduli c a l c u l a t e d u s i n g equa t ion 2 compare favorab ly with
those ob ta ined u s i n g t h e v i b r a t o r y t echn ique excep t a t t h e bedrock-
alluvium i n t e r f a c e . Thus, t h e p r o p e r t i e s i n t h e foundat ion a t l o c a t i o n
. 5 c a l c u l a t e d from t h e v i b r a t o r y t echn ique were modif ied accord ing t o
equation 2 and w e r e used t o e s t i m a t e s h e a r modulus d i r e c t l y under t h e
dam, where it was no t measured. This m o d i f i c a t i o n i s necessa ry because
the weight of t h e dam w i l l i n c r e a s e t h e c o n f i n i n g p r e s s u r e , t h u s i n c r e a s -
ing t h e modulus as compared wi th t h a t measured i n t h e foundat ion away
from t h e dam. Confining p r e s s u r e s w e r e ob ta ined from a s t a t i c f i n i t e
element code (FESS 4 1 ) developed at WES. A p l o t o f s h e a r modulus ve r sus
depth of t h e foundat ion d i r e c t l y under t h e c e n t e r l i n e of t h e dam i s
shown i n p l a t e 9 .
13. T e s t d a t a from t h e Bu Rec showed t h a t t h e enibankment mate-
r i a l s had a n average d* u n i t weight o f 119.6 p c f and an average mois-
t u r e c o n t e n t of 12.6 p e r c e n t . The s h e a r wave v e l o c i t y p r o f i l e ob ta ined
using t h e v i b r a t o r y technique i s , shown i n p l a t e 10 . A Po i s son ' s r a t i o
of 0.4 w a s assumed f o r t h e dam and t h e foundat ion m a t e r i a l .
1 4 . The s h e a r moduli and damping va lues used i n t h e f i n a l re-
sponse c a l c u l a t i o n s were ob ta ined by m o d i f i c a t i o n f o r t h e computed s h e a r . 4
s t r a i n l e v e l . The s h e a r moduli .and damping curves are shown i n
p l a t e s 11 and 1 2 , r e s p e c t i v e l y , f o r sand and i n p l a t e s 1 3 and 1 4 , re-
s p e c t i v e l y , f o r s a t u r a t e d c l a y s . The s h e a r moduli a s determined from
f i e l d d a t a o r equa t ion 2 were assumed t o be a t a s h e a r s t r a i n o f -4
10 p e r c e n t .
15. The depth t o bedrock, measured ' us ing s e i s m i c t echn iques ,
ranged from 80 t o 120 ft ( ~ p ~ e n d i x D ) . The bedrock p r o f i l e v a r i e d con-
s ide rab ly , and d i f f e r e n t depths were used i n t h e ana lyses . For t h e two-
dimensional ( 2 ~ ) a n a l y s e s , a h o r i z o n t a l bedrock p r o f i l e w a s assumed f o r
reasons o f s i m p l i f i c a t i o n and l a c k o f s p e c i f i c in fo rmat ion on depth o f
bedrock under t h e embankment.
16 . The fundamental pe r iod of t h e s t r u c t u r e w a s computed us ing C
Arnbrasey' s equat ion: '
T = fundamental pe r i od o f t h e dam, sec
H = he igh t o f dam, k. 120 f t
V = shea r wave v e l o c i t y i n dam, x 950 f t / s e c ( p l a t e 1 0 ) s
This computation gives a fundamental period of 0.33 sec .
PART I V : CALCULATIONS
General
17. The c a l c u l a t i o n s o f t h e response of t h e a l luvium 500 f t down-
s t ream from R i f l e Gap Dam were made using th r ee d i f f e r e n t methods o f
ana lys i s ; these were :
a . One-dimens i o n 1 ( 1 ~ ) lumped-mass a n a l y s i s o f foundation - a l l u v i urn only 8
b. .1D Four ie r ana lys i s o f foundation a l luvium only - 7
c. TWO-dimensional ( 2 D ) f i n i t e element a n a l y s i s , us ing mo a1 - supe rpos i t i on techniques , of foundat.ion and embankment 2
The same 2D f i n i t e element ana lys i s was a l so used t o c a l c u l a t e t h e re-
sponse of the embankment.
18. The response o f t h e .foundation mater ia l downstream from t h e
dam us ing the 1 D lumped-mass a n a l y s i s i s evaluated i n r e f e r ence 6 as
follows :
. ~ s s e n t i a l l ~ a s o i l deposi t i s represented by a s e r i e s of l a y e r s . . . , t h e m a s s of each l aye r i s lumped at t h e top and bottom o f each l a y e r and the masses a r e con- nected by shea r spr ings whose c h a r a c t e r i s t i c s a r e de- termined by t h e s t r e s s - s t r a i n r e l a t i onsh ips of t h e s o i l s i n t h e var ious layers . Similar ly , t h e damping c h a r a c t e r i s t i c s ,of t h e system are determined by the . s o i l p roper t ies ' .
Modal superposi t ion techniques are used t o evaluate t h e response o f the
depos i t t o the i npu t base motion. The base i s assumed t o be r i g i d .
19. The dynamic Four i e r ana lys i s of layered systems al lows con-
s i d e r a t i o n of energy r a d i a t i o n i n t o t h e bedrock and, "uses a one-
dimensional Four ie r t rans form ana lys i s t o compute t h e response of l i n e a r ,
v i s c o e l a s t i c , nonuniform s o i l depos i t s , subjected t o a base e x c i t a t i o n . 118
S o i l p roper t ies assumed were those obtained from t h e 1 D lumped-mass
a n a l y s i s taken from t h e f i e l d v ib ra to ry t e s t s and modified f o r t he ap-
p r o p r i a t e shear s t r a i n l e v e l . The base is assumed t o be e l a s t i c i n t h i s
ana lys i s . The amount of energy radiated. i n t o t h e bedrock depends upon
t h e r e l a t i v e s t i f f n e s s o f t h e s o i l and bedrock.
20. The f i n i t e element method of ana lys i s c o n s i s t s of developing
' a f i n i t e element network, obta in ing t h e s t f f f n e s s of each element,
assembling t h e elements i n t o a s t r u c t u r e , so lv ing t h e equat ions o f
equilibrium using modal superposit ion techniques, and eva lua t ing t h e
response of t h e s t r u c t u r e . The f i n i t e element mesh ( p l a t e 1 5 ) was gen-
e ra ted t o account f o r . ma te r i a l zones, s t r e s s zones, and t h e p h r e a t i c
surface. The element s i z e s were based on recommendations p resen ted i n
reference .9. The loca t ions f o r comparison of t h e observed and ca lcu-
l a t e d motions a re a l s o i n p l a t e 1 5 . The s o i l p roper t i e s were modified
fo r t h e shear s t r a i n l e v e l s obtained during e x c i t a t i o n . A h o r i z o n t a l
r i g i d base a t t h e depth of bedrock was assumed.
One-Dimensional Analyses of Foundation
21. The cases inves t iga ted using t h e ID analyses a r e l i s t e d i n
t a b l e 2. Cases 1-18 were analyzed using t h e lumped-mass a n a l y s i s , and
cases 19-21 were analyzed using t h e Fourier ana lys i s . The s h e a r modulus
p r o f i l e used was t h a t obtained from surface v ib ra to ry da ta ( p l a t e 6 ) ex-
cept i n cases 14-18, i n which t h e p r o f i l e used was t h a t from t h e
Rayleigh wave dispers ion da ta ( p l a t e 7 ) . The shear moduli o f t h e
. clay s o i l i n cases 9-13 and 19 were adjus ted by a f a c t o r of 1.875 t o
produce ,more comparable r e s u l t s . In a l l o t h e r cases , t h e modulus pro-
f i l e used was t h a t observed from i t s respect ive f i e l d measurement.' The
damping value is t h a t value used i n t h e f i n a l response c a l c u l a t i o n s
a f t e r t h e s o i l p roper t i e s have been modified f o r shear s t r a i n . The ex-
ac t depth t o bedrock was unknown; the re fo re , many depths were analyzed '
and t h e value l i s t e d i n t a b l e 2 i s t'hat f o r each respec t ive case . The
mater ia l c l a s s i f i c a t i o n r e f e r s t o t h e curves f o r modifying m a t e r i a l
proper t ies f o r shear s t r a i n . S r e f e r s t o sand and t h e modi f i ca t ion
curves i n p l a t e s 11 and 12 , C r e f e r s t o c l a y and t h e curves i n p l a t e s 13
and 1 4 , and M r e f e r s t o a layered mixture, a s designated i n t h e t y p i c a l
foundation p r o f i l e ( p l a t e 5 ) i n which t h e respec t ive curve was used f o r
each l ayer of mater ia l . S ix seconds of hor izon ta l input motion w e r e
used i n most analyses. The e f f e c t of using 1 2 sec of motion w a s
determined i n c a s e 13. I n case 12 , t h e e f f e c t o f using raw input d a t a
t h a t had no t been c o r r e c t e d fo r base-l ine s h i f t was inves-tigated. The
c a l c u l a t e d response s p e c t r a and maximum acce le ra t ions f o r t h e ID analy-
ses a r e g iven i n Appendix B. .
Two-Dimensional Analyses of Embankment and Foundation
22. Table 3 l i s t s t h e cases inves t iga ted us ing t h e 2D analyses.
For all c a s e s , t h e s h e a r moduli ( G) were conrputed from t h e v ib ra to ry
s h e a r wave v e l o c i t y p r o f i l e s f o r t h e -foundation and embankment. Because
no f i e l d measurements were taken d i r e c t l y under t h e embankment, t h e
s h e a r moduli p r o f i l e ' f o r . tha t loca t ion was modified, a s shown i n p l a t e 9 ,
from t h e v a l u e s computed us ing Hardinls e q ~ a t i o n . ~ Void r a t i o s of t h e
f o m d a t i o n m a t e r i a l were computed from v ib ra to ry da ta . The s o i l proper-
t i e s of s h e a r modulus and damping were modified f o r computed shear
s t r a i n s , and t h e 'damping value l i s t e d i s t h a t used i n t h e f i n a l ca lcula-
l a t i o n s . I n some of t h e ana lyses , t h e moduli and damping values were
changed as shown i n t a b l e 3 t o determine t h e e f f e c t s on t h e computed re-
sponse. For example, i n case 27 a t r i a l was made using a l a r g e r modulus
t h a n was measured. The modulus of t h e mate r i a l i n t h e embankment w a s
m u l t i p l i e d by 2 .5 , whi le t h a t of t h e mate r i a l .in t h e foundation was m u l -
t i p l i e d by 1 .5 . The damping value of t h e e n t i r e system w a s 4.6 percent .
I n c a s e 26, t h e foundat ion depth was 80 f t ; a depth of 100 f t was used
i n a l l o t h e r 2D ana lyses . Ninety modes of v i b r a t i o n were used i n t h e 2D
a n a l y s e s . S ix seconds o f hor izon ta l and v e r t i c a l a c c e l e r a t i o n d a t a were
used as i n p u t motion. It was important t o i.nclude t h e v e r t i c a l compo-
nent i n t h e s e a n a l y s e s because t h e energy source , an underground nuclear
exp los ion , produced l a r g e v e r t i c a l acce le ra t ions at R i f l e Gap Dam. The
c a l c u l a t e d response s p e c t r a and maximum acce le ra t ions a r e presented i n
Appendix C . A damping r a t i o of 5 percent was used f o r a l l s p e c t r a l
c a l c u l a t i o n s .
PART V: COMPARISONS OF OBSERVED AND CALCULATED RESPONSES
Method
23. A systematic method was needed t o compare the amplitudes and
frequency contents of observed motion records with those of computed mo-
I t i o n records . The amplitudes can be compared by us ing maximum accelera-
I t i o n s , while t h e frequency contents can be compared using response spec-
I tra. The number of peaks, periods at which peaks occurred, and r e l a t i v e
magnitudes of peaks a r e used i n t h e s p e c t r a l comparisons. One-
dimensional analysis r e s u l t s were compared with mot ions a t l oca t ion 5 ,
on. the surface of t h e alluvium. Two-dimensional ana lys i s r e s u l t s were
compared with motions a t l oca t ion 5 and a t dam loca t ions 1-3.
One-Dimens i o n a l Analysis
. ,
Observed
24. The maximum obse'rved h o r i z o n t a l acce l e ra t ion o f ' the alluvium
( loca t ion 5 ~ ) w a s 0.051 g. The acce l e ra t ion response spectrum ( p l a t e ~ 1 )
of the observed motion contained t h r e e peaks. The l a r g e s t occurred a t a
period o f 0.15 sec. A peak approximately two-thirds t h e s i z e of t h e
l a r g e s t peak occurred a t a period o f 0.33 sec , and a ' r e l a t i v e l y minor
peak occurred at a per iod of 0.51 s e e .
Cases 1-5 ( e f f e c t of depth of a l luv ium)
25. The e f f e c t ' of t h e depth t o bedrock , which var ied from 80 f t
i n case 1 t o 110 f't i n ca se 5 , was inves t iga t ed i n t hese cases . For
cases 1-5, the lumped-mass ana lys i s was used t o analyze a sand p r o f i l e
with shear moduli obtained from t h e su r f ace v ib ra to ry t e s t s . The re- . .
sponses o f cases 1-5 showed seve ra l marked s i m i l a r i t i e s t o t h e observed
responses ( p l a t e B 1 ) . One. s i m i l a r i t y .was the r e l a t i v e magnitudes of
I peaks, a s the second peak w a s two-thirds t h e s i z e o f t h e maximum peak
and the t h i r d peak (when' p r e s e n t ) w a s r e l a t i v e l y minor. The per iods a t
which peaks occurred were a l s o similar. The maximum peak of t h e re -
sponse spec t ra occurred i n the p e r i o d range of 0.15 t o 0.19 sec . In a l l
cases , a subsequent peak occurred i n t h e period range o f 0.31 t o
0.33 sec . A minor peak occurred i n t h e period range o f 0.49 t o 0.51 sec
for cases 4 and 5 bu t was not present f o r cases 1, 2, and 3. The maxi-
muin acce lera t ions ranged from 0.035 t o 0.04'6 g; t h e acce lera t ions were
l e s s than those observed.
26. A comparison of t h e response spec t r a f o r cases 1 and 5 i s
shown i n p l a t e 16. The peaks of t h e shallower depth p r o f i l e (80 f t ,
case 1) a r e s h i f t e d upwards and t o t h e l e f t , i n d i c a t i n g more response at
lower periods. of higher frequencies. P l a t e 17 shows a comparison of t h e
response spec t r a f o r the observed motion and t h a t ca lcu la ted i n case 2 ,
which had a depth t o bedrock of 85 f t . The da lcula ted response, case 2 ,
compares favorably with t h e observed and ind ica te s t h a t response can be
predicted using the 1D analys is method.
Cases 6 and 7 ( e f f e c t of a l l u v i a l s o i l type )
. 27. The e f f e c t of using a c l a y p r o f i l e was inves t iga ted i n cases
6 and 7 ( p l a t e ~ 2 ) . For cases 6 and 7, t h e curves i n p l a t e s 13 and 14
were used t o modify s o i l p roper t ies f o r shear s t r a i n . On t h e response
spec t ra f o r cases 6 and 7 , t h e maximum peaks occurred a t periods of 0.23
and 0.25 sec , and another peak, two-thirds t h e s i z e o f the maximum, oc-
curred a t periods of 0.14 and 0.15 sec. The maximum acce lera t ions cal-
culated were 0.033 and 0.044 g. The depth o f s o i l deposit i n case 6 w a s
90 f t and i n case 7 was 110 f t . ' A comparison of case 6 (c lay p r o f i l e )
with case 3 (sand p r o f i l e ) i s shown i n p l a t e 18. The response curve f o r
case 3 i s s h i f t e d upwards and t o t h e l e f t o f t h a t f o r case 6 , i nd ica t ing
more response at lower per iods f o r case 3 (sand) than for case 6 ( c l a y ) . '
The average shear s t r a i n used t o modify t h e s o i l p rope r t i e s f o r t h e
f i n a l response ca lcu la t ion i n case 3 w a s 6.5 x percent and i n
case 6 w a s 3.7 x percent . These s t r a i n s modulus reductions
of 15 and 32 percent i n cases 3 and 6 , respec t ive ly .
28. The s h i f t i n response s p e c t r a of case 3 ( sand) versus case 6
( c l a y ) ( p l a t e 18) is s imi l a r t o t h e s h i f t obtained ' i n case 1 versus case
5 ( p l a t e 16), where the depth increased from 80 t o 110 f t . The equation
f o r the fundamental period ( ~ ~ ) i of ho r i zon ta l s o i l l a y e r s , each
!
I having uniform mater ia l p roper t i es ( re fe rence l o ) , i s :
where Hi i s the thickness of t h e i t h
l a y e r , Gi
i s t h e shea r
modulus, g i s accelera t ion due t o g r a v i t y , and 'i i s t h e dens i ty .
This equation shows t ha t a deposi t w i l l 'have a s i m i l a r change i n funda-
mental per iod by increasing t h e depth and decreas ing t h e modulus, o r
vice versa. This i s i l l u s t r a t e d by t h e s i m i l a r response s p e c t r a s h i f t s
i n p l a t e 16 (case 1 versus case 5 ) f o r an i nc r ea se i n depth and i n
p la te 18 ( ca se 3 versus case 6 ) f o r a decrease i n modulus.
29. A comparison of the observed motion wi th t h a t c a l c u l a t e d i n
case 6 ( c l a y p r o f i l e ) i s shown i n p l a t e 19. The agreement between mea-
sured and computed responses w a s b e t t e r f o r c a se 2 ( p l a t e 17) t h a n f o r
case 6 ( p l a t e . 19 ) . I Cases 8-11 ( e f f e c t of l ayer ing)
30. P l a t e B3 shows comparisons o f observed and computed s p e c t r a
for cases 8-11. The assumed foundation p r o f i l e ( p l a t e 5 ) o f in terbedded
c lays , s i l t s , sands, and gravels was used i n ca se 8. The shea r moduli
were computed from the v ibra t ion da ta and modified f o r shea r s t r a i n by
the appropr ia te curves fo r sand o r c lay. Depth t o bedrock was 90 f t f o r
I cases 8 and 9. The response o f t h e motion i n case 8 w a s s i m i l a r t o t h e
response of case 6 fo r a 9 0 - f t ' p r o f i l e o f e n t i r e l y c l a y ma te r i a l . A
comparison o f computed spectra f o r cases 6 and 8 i s shown i n p l a t e 20.
Pla te 21 shows moduli versus depth p l o t s of, t h e v i b r a t o r y shea r d a t a ,
which have been modified fo r shea r s t r a i n , f o r cases 6 ( c l a y ) , 3 ( s a n d ) ,
and 8 ( l ayered mixture ) . The responses of cases 6 and 8 a r e s i m i l a r ,
showing t h a t t h e response a t t h e su r f ace ( l o c a t i o n 5R) i s c o n t r o l l e d by
low-velocity o r low-modulus l a y e r s i n t h e p rof i - l e , even though ca se 8
has sbme l aye r s - with higher modulus values t h a n does ca se 6.. A compar-
ison of t h e 'response spec t ra o f . the motions c a l c u l a t e d i n c a s e 8 with
, .those which were observed i s shown i n p l a t e 22 ; t he se spec t ra a r e not
s imilar .
31. Cases 9-11 used m a t e r i a l t ypes such a s t hose shown i n p l a t e 5 ,
but with the shea r moduli f o r t h e cohesive ma te r i a l increased by 87.5
percent. This w a s done t o produce a. c a l c u l a t e d response s imi la r t o t he
observed response. There were s i m i l a r i t i e s between t h e computed re-
sponses f o r cases 9-11 and t h e observed responses. The maximum peak of
the response s p e c t r a was a t a p e r i o d of 0.15 s e c i n c a s e 8 and a t a pe-
r iod of 0.16 i n ca se 9. The magnitude of t h e second peak i n a l l cases
was approximately two-thirds as g r e a t as t h a t o f t h e maximum peak.
Cases 10 and 11 had t h r e e peaks i n t h e , response s p e c t r a , while only two
peaks were v i s i b l e i n case 8. The maximum acce l e r a t i ons f o r cases 9,
10, and 11 were 0.042, 0.039, and 0.040 g, r e spec t ive ly .
Cases 12 and 13 ( e f f ec t of input motion)
32. The e f f e c t of base- l ine s h i f t of t h e observed accelerat ion a t
locat ion 4~ (bedrock ) was s tud i ed i n c a s e 1 2 , which w a s exactly the same
as case 11 except t h a t t h e i npu t d a t a i n case 1 2 were not corrected fo r
base-line s h i f t . A s shown i n p l a t e s , B3 (case 11) and ~4 (case 1 2 ) ,
there was no appreciable d i f f e r e n c e i n t h e response spec t ra . Both cases
12.and 1 3 had a maximum a c c e l e r a t i o n of 0.040 g.
33. The e f f e c t of ' us ing 1 2 s e c o f input motion was investigated
i n case 13. Case 13 was e x a c t l y t h e same a s ca se 11 except t h a t 6 sec
of input motion -was used i n c a s e 11. Because t h e r e was no appreciable
di f ference between t h e response s p e c t r a f o r cases '13 and 11 (p la t e B & ) o r
between the maximum a c c e l e r a t i o n s (0.040 g i n both c a s e s ) , 6 sec of in-
put motion was used i n a l l o t h e r cases .
Cases 14-18 ( e f f e c t o f f i e l d moduli)
34. As prev ious ly s t a t e d , t h e s o i l p rope r t i e s f o r cases 14-18
were determined from t h e Rayleigh wave d i spe r s ion d a t a , a s shown i n
p l a t e 7. The only s i m i l a r i t y o f t h e c a l c u l a t e d response with t he ob-
served response was t h a t case 1 5 had a maximum. acce l e r a t i on of 0.053 g 1 and case 1 4 had a maximum a c c e l e r a t i o n o f 0.044 g. Comparisons a re
shown i n p l a t e B5. Case 1 4 had a number of peaks , wi th t h e maximum peak
obcurring a t a period of 0.24 sec . Cases 15-17 each had two peaks, with
- the maximum occurring a t a per iod of 0.31 t o 0.35 sec and a lesser peak
occurring at a period of 0.14 t o 0.17 sec . The maximum accelerations
ranged from 0.070 t o 0.074 f o r cases 16 and 17 . The s o i l properties in
case 1 4 were m d i f i e d f o r shear s t r a i n using p l a t e s 1 3 and 1 4 ; plates 10
and 11 were used t o modify t h e s o i l p roper t ies f o r shear s t r a i n for
cases 15-17. P la t e s 23 and 24 compare t h e observed responses with the
ca lcu la ted responses i n cases 1 4 and 1 5 , respect ively. These plates do
not show as good a comparison a s do p l a t e s 1 7 and 1 9 , which used the
modulus determined from the sur face v ibra tory data.
Cases 19-21 ( e f f e c t of analysis method and damping )
35. P la t e ~6 shows comparisons o f observed and computed responses
for cases 19-21, which used t h e 1D Fourier ana lys is fo r computations of
response. The e f fec t of using t h i s type ana lys is a s opposed t o the 1 D
lumped-mass ana lys is is given i n p l a t e 25. This p l a t e shows a compari-
son of t h e response spec t ra f o r case 20 (Fourier ana lys is ) with the re-
sponse spec t ra f o r case 2 (lumped-mass a n a l y s i s ) . Both cases had the
same foundation mater ial proper t ies .and input motion. The assumed shear
wave veloci ty of t h e bedrock was approximately f i v e times greater than
the shear wave veloci ty of t h e overlying s o i l l ayer . 'Note tha t the re-
sponse spec t ra a r e s imi l a r f o r cases 20 and 2. The response for case 20
i s l e s s than t h a t f o r case 2. The maximum acce lera t ion f o r case 20 i s
0.033 g, whereas f o r case 2 it is 0.041 g. A l i k e comparison can be
made of cases 19 (p la t e ~ 6 ) and 8 ( p l a t e B3).
36. The e f f e c t of reducing the i n t e r n a l s o i l damping in the
Fourier analysis was s tudied i n case 21, which was s imi l a r t o case 20
except t h a t t h e damping was reduced by 100 percent . The maximum accel-
e ra t ion for case 21 was increased t o 0.035 g , as compared t o 0.033 g for
case 20. The response s p e c t r a were a l s o very s i m i l a r ( see plate ~6 ) . Although it w a s expected t h a t t he re would be a grea ter difference i n the
damped calculated responses, t h i s was not t r u e f o r the condition a t
R i f l e Gap D a m .
Two-Dimens i o n a l A n a l y s i s
General
37. The observed r a d i a l and v e r t i c a l motions at l o c a t i o n s 1, 2 ,
3, and 5 were compared with t h e c a l c u l a t e d motions. Transverse motions
were measured, but could not be c a l c u l a t e d u s i n g a 2 D a n a l y s i s method.
P l a t e 4 shows t h e loca t ions o f t h e PAT'S which measured t h e observed mo-
t i o n s , and desc r ip t ions 'of t h e l o c a t i o n s a r e g iven i n table 1. The lo -
ca t ions from which t h e c a l c u l a t e d motions were t a k e n a r e shown on t h e
f i n i t e element network ( p l a t e 1 5 ) . It w a s necessa ry f o r 2D a n a l y s i s
t h a t a l l loca t ions be i n t h e same v e r t i c a l p lane . Although t h i s i s not
t h e t r u e f i e l d case , the l a t e r a l o f f s e t s between PAT and t h e v e r t i c a l .
plane assumed f o r ana lys i s were not cons ide red l a rge . w i t h r e s p e c t t o t h e
hor izon ta l d is tances i n t h e f i n i t e element network. The d e t a t l e d com-
par isons of t h e observed and c a l c u l a t e d responses f o r t h e r a d i a l and
v e r t i c a l components at l o c a t i o n s 1, 2, 3, .and 5 a r e g iven i n t a b l e 4.
The response s p e c t r a f o r t h e observed and c a l c u l a t e d motions f o r loca-,
t i o n s 1, 2, 3, and 5 . a r e p resen ted i n p l a t e s ~ 1 ~ 8 .
Case 22 ( 2 ~ compared with 1D a n a l y s i s )
38. Case 22 w a s a 2D f i n i t e element a n a l y s i s of t h e 120-ft-high
embankment and 100-ft-deep foundat ion a s shown i n p l a t e 15. Although
b e t t e r comparisons could be made i n t h e 1 D ana lyses f o r s h a l l o w e r foun-
da t ions a t l o c a t i o n 5 (a l luvium), t h e se i smic p r o f i l e s ( ~ p p e n d i x D) ' i n -
d i c a t e d t h a t an average depth o f 100 f t would be a more v a l i d assumption.
The shear moduli of t h e m a t e r i a l s w e r e computed from t h e v i b r a t o r y s h e a r
wave v e l o c i t i e s . The shear wave v e l o c i t y p r o f i l e s are shown i n p l a t e 10
, f o r t h e embankment and i n p l a t e 6 f o r t h e founda t ion a t l o c a t i o n 5
(a l luvium). The shear modulus p r o f i l e o f t h e founda t ion d i r e c t l y under
t h e c e n t e r l i n e of t h e embankment, which was t a k e n from t h e v i b r a t o r y
d a t a and modified f o r conf in ing p r e s s u r e s , i s shown i n p l a t e 9 . The ma-
t e r i a l i n t h e foundation was assumed t o respond as a sand, and t h e
curves i n p l a t e s 11 and 1 2 w e r e used t o modify m a t e r i a l p r o p e r t i e s f o r
shear s t r a i n . The mate r i a l i n t h e embankment i s a c o h e s i v e material,
and t h e curves i n p l a t e s 1 3 and 1 4 were used t o modify material
. .
p r o p e r t i e s f o r s h e a r s t r a i n . The damping value o f 5.3 p e r c e n t was t h e
, average used d u r i n g t h e f i n a l response c a l c u l a t i o n a f t e r t h e m a t e r i a l
p r o p e r t i e s had been modified f o r s h e a r s t r a i n ( s e e t a b l e 3).
39. Case 22 c a l c u l a t e d motions were s i m i l a r t o t h e observed mo-
t i o n s . The p e r i o d s of t h e maximum c a l c u l a t e d peaks were s i m i l a r t o t h e
observed maximum peaks f o r t h e r a d i a l components at al l l o c a t i o n s . The
maximum c a l c u l a t e d a c c e l e r a t i o n s a t a l l r a d i a l and v e r t i c a l l o c a t i o n s
were on ly s l i g h t l y l e s s t h a n t h e observed a c c e l e r a t i o n s except a t loca -
t i o n s 2R and 2V where t h e c a l c u l a t e d a c c e l e r a t i o n s were h i g h e r than t h e
observed. The pe r iods a t which t h e peaks occurred i n t h e v e r t i c a l
motion response s p e c t r a were d i f f e r e n t from t h o s e observed. The ca lcu-
l a t e d response had a maximum peak at t h e pe r iod where t h e . observed
response had t h e second o r t h i r d l a r g e s t peak. In t h e same way, t h e
maximum observed peak occur red i n t h e same p e r i o d s as t h e second o r
t h i r d l a r g e s t peaks on t h e c a l c u l a t e d response curves:
40. The e f f e c t o f t h e a d d i t i o n o f t h e v e r t i c a l a c c e l e r a t i o n s t o
t h e response of l o c a t i o n 5R can be seen i n p l a t e 26, which shows t h e re-
sponse s p e c t r a and maximum a c c e l e r a t i o n s f o r c a s e s 4 and 22. Note t h a t
t h e response s p e c t r a and maximum a c c e l e r a t i o n s a r e similar. The founda-
t i o n s o i l p r o p e r t i e s assumed i n c a s e 22 a r e t h e same as t h o s e assumed i n .
c a s e 4. Case 4 w a s a 1D a n a l y s i s and on ly t h e h o r i z o n t a l input motion
could be used. Case 22 w a s a 2D a r ia lys i s and used b o t h t h e h o r i z o n t a l
and v e r t i c a l bedrock a c c e l e r a t i o n h i s t o r i e s a s i n p u t .
Case 23 ( e f f e c t o f i n c r e a s e d modulus)
41. Case 23 was computed t o show t h e e f f e c t o f . inc reas ing t h e
shear modulus of t h e material i n t h e enibankment and foundat ion. Other
assumptions were t h e same as i n c a s e 22 with a 120-f t c l a y embankment
and a 100-f t sand foundat ion. The v a l u e o f 4.7 p e r c e n t damping w a s used
i n t h e f i n a l response c a l c u l a t i o n . R e s u l t s are shown i n . p l a t e s 27-34.
The c a l c u l a t e d responses i n c a s e 23 of t h e v e r t i c a l motions a t l o c a t i o n s
3V and 5 V w e r e s i m i l a r t o t h o s e observed. The peaks on t h e computed re-
sponse s p e c t r a occurred at t h e s a m e p e r i o d s a s d i d t h o s e observed, ' and
t h e . r e l a t i v e magnitudes w e r e s i m i l a r . The maximum a c c e l e r a t i o n s of t h e
v e r t i c a l components were h i g h e r t h a n t h o s e observed excep t at l o c a t i o n 5V.
The computed hor izonta l maximum acce lera t ions were usual ly lower except
a t loca t ion 2R, and the computed acce lera t ion a t loca t ion 5R w a s 0.050 g,
as compared with an observed acce le ra t ion of 0.051 g. The response
spectra f o r t h e observed and ca lcula ted components o f the r a d i a l motion
had peaks occurr ing a t the same per iods , but t h e maximum observed w a s
often a t a period corresponding t o the second o r t h i r d ca lcu la ted maxi-
mum, and vice versa.
Case 24 ( e f f e c t of reduced modulus)
42. The e f f e c t of a reduct ion o f .shear modulus was computed i n
case 24. The assumptions were s imi l a r t o those i n cases 22 and 23 except
tha t i n case 24 the shear moduli of t h e foundation and embankment were
mult ipl ied by the value 0.5. The ca lcula ted motion f o r case 24 had only
a few s i m i l a r i t i e s t o the observed motion. The maximum acce le ra t ions a t
locat ions 2V and 5V were. 0.042 and 0.092 g, respec t ive ly , and were simi- '
l a r t o those observed. The' hor izonta l maximum acce lera t ions were usu-
a l l y lower than those observed except a t loca t ion 2R. The computed
v e r t i c a l acce lera t ions a t l oca t ions 1 V and 3V were lower and h igher , re-
spect ively, than t h e observed acce lera t ions . The pe r iod - of t h e maximum,
and usual ly only, peak on t h e response spec t r a occurred i n the range of
-0.30 t o 0.34 sec , and the period of t h e second peak, present only i n the
v e r t i c a l motion response spec t r a , , was i n the range o f 0.14 t o 0.18 sec. .
Case 25 ( e f f e c t of reduced dampint?)
43. Case 25 invest igated t h e e f f e c t of reducing t h e damping value
used i n response ca lcula t ions . The only difference between cases 22 and
25 was t h a t t h e damping value used f o r case 25 was only two-thirds as
great a s t h a t used for case 22. Consequently, t h e maximum acce lera t ions
for case 25 were grea ter than those f o r case 22 , ' e s p e c i a l l y i n the ra-
d i a l components of locations 1-3 on t h e dam. The computed response spec-
t r a ' for cases 22 and 25 had t h e same shape except t h a t a few more minor
spikes were present i n the response spec t r a f o r case 25. This means
tha t only the amplitude of t h e motion was changed and t h e frequency con- .
t en t remained e s s e n t i a l l y unal te red between cases 22 and 25.
Case 26 ( e f f e c t of depth of alluvium)
44. The e f f e c t of an 80-ft-deep foundation w a s inves t iga ted i n
c i s e 26. This analysis was .made because better comparisons could be
made i n the 1D analysis a t locat ion 5R, downstream from t h e dam, with
t he shallower p ro f i l e . A 120-ft c l a y .embankment , sand foundation, and
moduli obtained from the surface v ib ra to ry d a t a were used a s i npu t , as
i n case 22. The maximum accelerat ions computed a t l oca t ions 1 and 3
were s imilar t o those observed. Similar per iods of t h e p e a k s . f o r the
v e r t i c a l components a t locations 1-3 i n t h e dam were measured. Compari-
sons of the computed -responses with t h e observed responses a t l oca t ions
3R and 3V are shown ' in p la tes 35 and 36, r e spec t ive ly . The computed re-
sponses a t locations 2R and 2V were g r e a t e r than t h e observed, and a t
loca t ions 5R and 5V were smaller t h a n t h e observed. The peaks occurr ing
i n t h e range of 0.12 t o 0.17 sec i n t h e observed response spec t r a f o r
loca t ions 1 R and 1 V were only minor i n t h e computed response f o r case 26.
Note t h a t not as good a comparison could be made a t l o c a t i o n 5 R f o r
case 26 (p l a t e ~ 7 ) as could be made with t h e 1 D ana lys i s i n case 1
( p l a t e ~ 1 ) . This may be due t o t h e increased s t r a i n i n t h e mater ia l
from the inclusion of the v e r t i c a l acce le ra t ion .
Case 27 (e f fec t of s t i f f foundation under s t i f f e r dam)
45. In case 27, the e f f ec t of increas ing t h e shea r modulus of t h e
mater ia l i n the foundation by a f a c t o r d i f f e r e n t from t h a t i n t h e embank-
ment was investigated. The shear modulus of t h e ma te r i a l i n t he founda-
t i o n was increased by the f ac to r 1 .5 , as i n ca se 23. A f ac to r o f 2.5
was used t o increase the shear modulus o f t h e ma te r i a l i n the embank-
ment. ' As expected, the responses measured a t t h e alluvium loca t ions 5R
and 5V were s i m i l a r t o those measured i'n case 23 ( p l a t e s 37 and 38 ) .
The response i n the embankment was similar t o t h a t observed. The maxi- . '
mum accelerat ion and response s p e c t r a computed at loca t ions 2R and 2~
were very s imilar t o the observed (p l a t e s 39 and 40). A t locat ions 3R
and 3 V , peaks of the calculated response s p e c t r a occurred a t t he same
per iods as those i n the observed spec t r a , b u t t h e maximum acce le ra t ion
a t loca t ion 3V was much higher t han the observed. The computed maximum
acce le ra t ion a t locat ion 1 V was s imi l a r t o t h e observed acce le ra t ion ,
but a t locat ion l R , the computed a c c e l e r a t i o n was much lower than the
observed acceleration.
PART V I : DISCUSSION
One-Dimens i o n a l Analysis
46. The U> ana lys i s is used t o determine t h e response of semi-
i n f i n i t e hor izonta l s o i l l ayers . For t h i s reason , t h e 1 D analysis could
b e used only t o ca l cu l a t e response at l o c a t i o n 5R on the alluvium down-
stream of Ri f le Gap Dam. During t h e a n a l y s i s , it became apparent t h a t
many f a c t o r s were vital i n accura te ly s imula t ing response. These fac-
t o r s include t h e following:
a. Shear moduli ,of t h e i n s i t u medium - b . - Depth t o bedrock
c . Relat ionship of shear modulus and damping t o s t r a i n am- - p l i t ude f o r modification o f s o i l p roper t ies
47. Use of the i n s i t u shear moduli as measured by WES i n t he
seismic f i e l d i nves t iga t ion using t h e s u r f a c e v ibra tory technique gave
computed r e s u l t s comparable t o the f i e l d observat ions . The data deter-
mined by the Rayleigh wave d ispers ion technique d id not give calculated
results a s good a s those ca lcu la ted us ing t h e v ibra tory technique.
48. The depth t o bedrock i n t h e foundation mater ia l varied con-
s ide rab ly throughout t h e Ri f le Gap Dam a rea . No borings were made a t
t h e s i t e of l oca t ion 5 on the alluvium downstream from the dam.' Thert-
f o r e , no accurate determination of s o i l depth could be used i n the lD
analyses . The e f f e c t of depth t o bedrock is shown i n p l a t e 16, which
compares t he response of an 80-ft-deep depos i t with t h a t of a 110-ft-
deep depos i t . Be t te r agreement wi th t h e observed response was obtained
us ing t h e shallower bedrock depths.
49. The type o f mater ia l used, sand o r c lay , determined the re-
l a t i o n s h i p used t o modify the ma te r i a l p r o p e r t i e s f o r shear ' s t ra in l eve l .
The comparison o f mater ia l types i s made i n p l a t e 18 f o r cases 3 and 6.
Both t h e maximum acce le ra t ions and response s p e c t r a were considerably
d i f f e r e n t for t h e two cases i nves t iga t ed . For t h e foundation material
a t R i f l e .Gap Dam, b e t t e r agreement with t h e observed data was obtained by
cons ider ing t h e mater ia l as sand. The g ranu la r mater ia l was present i n
bdth Bu Rec borings ( p l a t e . 3 ) , but cohesive m a t e r i a l was a l s o present
and r e s u l t s comparable t o those observed could be obtained only by mul-
t i p l y i n g t h e cohesive modulus by a f a c t o r of 1.875, which a c t u a l l y gave
about t h e same modulus a s t h a t f o r t h e sand curves a t t h a t shear s t r a i n
l e v e l . Because t h e exact s o i l p r o f i l e i s no t known a t l o c a t i o n 5 , it
can only be concluded t h a t t h e m a t e r i a l i n t h e p r o f i l e a t l o c a t i o n 5
responded more c lo se ly t o the sand curves used i n modification of s o i l
p rope r t i e s ( ~ l a t e s 11 and 12) .
50. For t h e motions measured a t R i f l e Gap Dam, the responses did
no t change i n cases 11-13 ( p l a t e ~ 4 ) . Case 11 used 6 .sec o f input mo-
t i o n t h a t had been corrected f o r base- l ine s h i f t , whereas t h e input mo-
t i o n i n case 1 2 w a s not cor rec ted . Case 1 3 used 1 2 sec of input motion.
The agreement of cases 11 and 1 2 showed t h a t t h e a c t u a l acce l e r a t i on
d a t a a t l o c a t i o n 4~ d id not have an apprec iab le ba'se-line s h i f t . The ' (
comparison of cases 11 and 1 3 showed t h a t , when us ing an e l a s t i c analy-
s i s , t h e maximum response occurred b e f o r e 6 s ec and was not changed by
t h e addi t ion of 6 sec more of e x c i t a t i o n .
51. The input motion f o r a l l analyses was t h a t observed a t loca-
t i o n 4 on bedrock i n t h e gate chamber ' ( see p l a t e 4 ) . The motion at lo - ,
ca t ion 4 was assumed t o occur i n t h e bedrock under lying t h e foundation
p r o f i l e a t l o c a t i o n 5 . Most o f t h e analyses i nd i ca t ed t h a t t he response
a t l oca t i on 5R could be pred ic ted wi th t h e 1 D ana lys i s ; t hus , t h e as-
sumption t h a t t he motion observed a t l o c a t i o n 4 w a s bedrock motion was
apparent ly a v a l i d assumption.
52. The 1 D ana lys i s gave r e s u l t s very s i m i l a r t o those observed
f o r t he al luvium ( l o c a t i o n 5 ~ ) . With t h e a d d i t i o n o f the. v e r t i c a l mo-
t i o n input i n t he 2D ana lys i s , p l a t e 26 shows t h a t good agreement be-
tween t h e 1 D and 2D ana lys i s r e s u l t s i s obtained. This means t h a t the
much simpler and cheaper U) a n a l y s i s can b e used t o p red ic t t h e hor i -
zon t a l motion i n a semi- inf ini te s o i l depos i t even during three-dimensional
dimensional e x c i t a t i o n .
~wo-~ imens i o n a l Analys i s
53. S imi l a r r e s u l t s were obtained at l o c a t i o n s 5R and 5V f o r
, - . . .... - . ; - > - . -:::- 3 - 7 - -= ,-..-; - =. . - - . - . , - - I.-..., ..i..- ' I . 7. = _ _-.. : . .: . . . - - - - C - - . -.----.--A -. - . A , - ' L i. A.
, cases 23 and 27, as shown i n p la tes 37 and 38. The only d i f fe rence i n
t h e two cases was the increase of modulus i n t h e embankment f o r case 27
over t h a t for case 23. This shows t h a t t h e instrument loca ted more than
520 ft downstream from the 120-ft-high dam w a s a t a s u f f i c i e n t d is tance
from t h e dam tha t ' i ts response was not a f f e c t e d by t h e s t r u c t u r e .(gener-
a l l y ca l l ed free-f ie ld response 1. . 54. The response of t h e ' foundation mater ia l was b e s t p red ic t ed by
case 23 (p la tes 33 and 34) i n which t h e v ib ra to ry shea r modulus was mul -
t i p l i e d by 1.5. However, comparable r e s u l t s were obtained f o r case 22
i n which the -shear modulus was t h a t computed from t h e f i e l d measurements. 4
Thus, t he shear wave v e l o c i t i e s measured us ing t h e ' sur face v ibra tory
technique can be used i n t h e 2D f i n i t e element models.
5 5 . The responses computed a t loca t ions 2R and 2V were usua l ly
g r e a t e r than those observed. Bet ter agreement was obtained by increas-
i n g t h e modulus i n t h e s t ruc tu re , and s i m i l a r r e s u l t s were obtained f o r
case 27, as shown i n p l a t e s 39 and 40.
56. A change i n the damping value f o r t h e s t r u c t u r e , as i n case
25, had only a s l i g h t e f f e c t on the magnitude of t h e response. The ra-
d i a l components of motion were more a f f e c t e d than t h e v e r t i c a l compo-
nents. Changing the damping value d id not cause a noticeab1.e change i n
t h e periods of the peaks.
57. The response a t the c r e s t of t h e dam was t h e most d i f f i c u l t
t o p red ic t . Most cases produced s in i i la r maximum acce lera t ions but had
only one peak a t a per iod o f 0.30 t o 0.33 s e c , which i s near t h e f'unda-
mental period of the s t r u c t u r e , and did not have s u b s t a n t i a l response a t
lower periods, as w a s observed. Attempts t o produce a g rea te r response
a t the lower periods by increasing t h e modulus of t h e dam were success-
ful, b u t the maximum accelerat ions were reduced considerably.
58. The change of modulus produces d i f f e r e n t modal frequencies of
t h e s t r u c t k e . I f these a r e d i f f e r e n t .from t h e major frequencies o f the
inpu t , the responses a re low. This could have been t h e reason f o r t h e '
low response i n case 27 a t locat ions 1 R and lV, where a grea ter response
' , was expected. Thus, it is 'important i n design and ana lys is t h a t a num-
b e r of inputs be used t o produce a smooth response spectrum so t h a t the
PART V I I : CONCLUSIONS
59. The following conclusions can be drawn from t h e 1 D analyses :
a. The response of horizontal s o i l layers can be predicted - using a ID analysis.
b_. The lumped-mass and Fourier analyses give s imi l a r r e s u l t s for a p r o f i l e i n which t h e r e i s a 'def in i te change i n shear wave veloci t ies between the bedrock and s o i l . For the ana lys is of Rif le Gap Dam, the ve loc i ty of the bed- rock mater ia l was approximately f ive times t h a t of t h e s o i l .
c . It is important t o have an accurate determination of the - s o i l p r o f i l e .
d. It is important t o determine t h e exact depth t o Sedrock. - e . The s o i l property modification curves ' for shear s t r a i n -
l e v e l are applicable.
f . The shear wave veloci t ies determined using t h e surface - vibratory technique can be used i n t h e 1D analyses.
60. The following conclusions can b e drawn from the 2D analyses:
a . An instrument placed a t a d is tance f i v e times the height - of t h e dam w i l l give f r ee - f i e ld response.
b. The shear wave veloci t ies measured using t h e surface v i - b ra tory technique can be used i n the 2D analyses, bu t due t o t h e inclusion of the v e r t i c a l input motion, a more similar response was ca lcu la t ed a t ~ i f l e Gap Dam when the modulus was increased by 50 percent.
c . -Due t o the complex geometry and mater ia l propert ies . o f - t he s t r u c t u r e , use of the f i n i t e element ana lys is is nec- essary t o predic t the response o f various loca t ions i n
' t he s t r u c t u r e .
d. It is important t o use more t h a n one input motion t o . ana- - lyze a s t ruc ture . A v a r i e t y of input frequencies is nec- essary t o f i n d the maximum response.
e . here was c lose r agreement between computed aqd observed - maximum accelerations than between shapes o f computed and observed response spec t ra .
61. For t h e ana lys is of Ri f le Gap Dam, t he following assumptions
provided the b e s t agreement between the observed and ca lcula ted motions :
a. One-dimensional analysis ( l o c a t i o n 5R on alluvium) - ( 1 ) Lumped-mass analysis method
- . ( 2 ) Shear modulus determined from vibra tory t e s t d a t a
4 ( 3 ) Damping from re l a t i onsh ips by Seed and I d r i s s f o r
, shear s t r a i n
( 4 ) Modulus modified from re la t io r i sh ips by seed and Idriss fo r shear s t r a i n
( 5 ) Sand ma te r i a l
( 6 ) 85-f t depth t o bedrock
- b . TWO-dimens i o n a l ana lys i s
('1) F i n i t e element modal superposing ana lys i s method
( 2 ) Shear modulus determined from v ibra tory t e s t d a t a and increased 50 percent
( 3 ) Damping from r e l a t i o n s h i p by Seed and I d r i s s f o r shear s t r a i n
( 4 ) Modulus modified from re l a t i onsh ips by Seed and I d r i s s fo r shea r s t r a i n
( 5 ) Sand i n foundation
( 6 ) Clay i n embankment
( 7 ) Average 100-ft depth t o bedrock
LITERATURE CITED
U. S. Department of I n t e r i o r , Bureau o f Reclamation, "R i f l e Gap Dam and Road Relocation," Spec i f ica t ion NO. DC-6120, 1964, Washing- t o n , D . C .
Fowler, J. , "Motion of R i f l e Gap Dam, R i f l e , Colorado; P r o j e c t Rul ison Underground Nuclear Detonation ," Miscellaneous Paper S-70-1, Jan 1970, U. S. Army Engineer Waterways Experiment S t a t i o n , CE, Vicksburg, Miss.
Hardin, B. 0. and Drnevich , V. P. , "Shear Modulus and Damping i n S o i l s ," Technical Report UKY 27-70-CE 3 , s o i l Mechanics S e r i e s No. 2 , Jul 1970, Univers i ty of Kentucky, Lexington, Ky.
Seed, H. B. and I d r i s s , I. M . , "So i l Moduli and Damping Fac to r s f o r Dynamic Response Analyses, " Report No. EERC 70-10 , Dec 1970, Uni- v e r s i t y of Ca l i fo rn i a , College o f Engineering, Earthquake Engineer- i n g Research Center , Berkeley, C a l i f . O f f i c e , Chief o f ~ n ~ i n e e r s , "Earthquake Studies f o r Earth and Rock- f i l l Dams ," Engineer Technical L e t t e r No. 1110-2-79 , 12 J a n 1970, Washington, D. C .
I d r i s s , I. M . , Dezfulian, H. , and Seed, H. B. , "Computer Programs f o r Evaluat ing t h e Seismic Response o f So i l Deposi ts wi th Non- Linear C h a r a c t e r i s t i c s Using Equivalent Linear Procedures , I f
Apr 1969, Univers i ty of Ca l i fo rn i a , Geotechnical Engineering, Berkeley, Ca l i f .
Roesset , J. M.. and Whitman, R . V . , " ~ h e o r e t i c a l Background f o r Amplif icat ion Studies ," So i l s Engineering Div is ion Publ ica t ion No. 231, Mar 1969, Department of C i v i l Engineering, Inter-American Program, Massachusetts I n s t i t u t e o f Technology,. Cambridge, Mass.
Roesset , J. M. and Hagann, A. J. , "Users Manual, Program Dyfals I ," Jul 1969, Department of C i v i l Engineering, Div is ion of S o i l Mechan- i c s , Massachusetts I n s t i t u t e of Technology, Cambridge, Mass.
I d r i s s , I. M. , " ~ i n i t e Element Analysis f o r Seismic Response o f Ear th Banks , I 1 J ou rna l , S o i l Mechanics and Foundations D iv i s ion , American Soc ie ty of C i v i l Engineers. Vol 94, No. SM3, Paper 5929, May 1968, pp 617-636.
I1 I d r i s s , I. M. and Seed, H. B. , Seismic' Response o f Horizontal S o i l Layers," J o u r n a l , S o i l Mechanics and Foundat i ons Divis ion , American Soc i e ty o f C i v i l Engineers, Vol 94, No. S M ~ , Paper 6043, Jul 1968, pp 1003-1031.
Table 1
Summary of Equipment Used, Locations, and Field Measurements
Pa r t i c l e P a r t i c l e Peak Peak Transducer Acceleration Velocity Acceleration Velocity
No. - Location* Orientation Transducer Transducer g ' s i p s
1 Crest of dam Vertical x 0.062 Radial x : 0.094
2 ' Downstream face Vertical of dam Radial
3 ' Near toe of dam Vertical Radial
4 Gate chamber Vertical Radial Transverse
5 Alluvium
6 Alluvium
Vertical Radial Transverse
. Vertical Radial Transverse
7 Crest o f dam Vertical Radial Transverse
- - -- -- - -
Note: I n i t i a l a r r i v a l of motion was 6.9 sec a f t e r detonation. See p l a t e 4 .
Table 2
Cases for One-Dimensional Analyses, Location 5R
on Alluvium 500 Ft Downstream from Toe of Dam
F ie ld Test from Which Material Depth t o Material
Case Type Propert ies Were Shear Damping Bedrock Class i - No. Analysis - Determined Modulus % ft f i ca t ion* Remarks
1 Lumped-mass Vibratory . C 3.9 80 S 2 Lumped-mass Vibratory C 3.8 85 S 3 Lumped-mass Vibratory C 3:7 90 S ' b Lumped-mass Vibratory G 3.5 i00 S 5 Lumped-mass Vibratory C 3.7 110 S
6 Lumped-mass Vibratory C 3.2 90 C 7 Lumped-mas-s Vibratory C 3.3 110 C 8 Lumped-mass Vibratory C 3.3 90 M 9 Lumped-mass Vibratory 1.875G4' 3.3 90 M
10 Lumped-mass Vibratory 1.8750- 3.2 100 M
11 Lumped-mass Vibratory 1.875G*+ 3.2 110 M 12 Lumped-mass Vibratory 1.875G** 3.2 110 M Original acce lera t ion
da t a used fo r input 1 3 Lumped-mass Vibratory 1.875c** 3.2 110 M 12 sec of input fo r
ca lcula t ing response , 1 4 Lumped-mass Rayleigh 2 C 4.0 110 C
15 Lumped-mass . Rayleigh 2 C 4.7 110 S
16 Lumped-mass Rayleigh 1 G b.7 125 S 17 Lumped-mass Rayleigh 1 C 5.9 80 S 18 Lumped-mass Rayleigh 1 C 3.2 80 C 19 Fourier Vibratory 1.875c+* 3.4 80 M 20 Fourier Vibratory C 3.8 85 S 21 Fourier Vibratory C 1.9 85 . S 1/2 damping of case 20
* S r e f e r s t o sand and the modification curves i n p l a t e s 11 and 12 , C r e f e r s t o clay and the curves in p l a t e s 13 and 1 4 , and M refers t o a mixture as designated i n the t yp i ca l foundation p r o f i l e in p l a t e 5. ** Only the shear moduli of the clay layers were changed by t h i s f ac to r .
Table 3
Cases f o r Two-Dimensional Analyses
Foundation Case Damping Depth No. - Shear Modulus % ft Remarks
27 1.5G ( foundation) 4.6 100 2 . 5 ~ (dam) .
2/3 damping of case 22
~ - ~
Note: Six seconds o f ho r i zon ta l and v e r t i c a l acce le ra t ion data were used as input motion. The modal superpos i t ion analysis method was used. Ninety modes o f v i b r a t i o n 'were considered.
Table b
C-arison of Observed'and Calculated Responses f o r 2D Analysis
Amplitude Ratio Period of Peak, sec of Peaks
Maximum Number Second Third Second Third Case Acceleration of Maximum Largest Largest t o t o NO. - K' s Peaks Peak Peak Peak Mkximum Maximum Remarks
Location l R , Radial Component, Crest of Dam
Observed 0.094 3 0.32 0.12 0.17 3/4 3/4 22 0.073 1 0.31 23 0.052 3 0.27 0.32 0.14 t o 0.18 4/5 2 /3 24 0.041 1 0.32 25 0.119 2 0.31 0.19 1 / 3 26 0.091 1 0.29 Minor spike a t 0.17 sec 27 0.035 3 0.29 0.15 t o 0.18 0.52 2 / 3 1 / 3
Location l V , Vert ical Component, Crest of Dam
Observed 22
' 23 24 25 26 27
Observed 22 23 24 25 26 27
Observed 22 23 24 25 26 27
0.13 . 0.31. 0.21 2 / 3 i/ 3 0.33 0.30 0.14 1 /2 0.34 0.16 1 / 4 0.32 - 0.19 1 / 3 0.36 0.15 t o 0.17 1 / 3 0.30 0.13 1 /2
Location 2R. ~ a d i a l Component. Halivay D o v n Face of Dam
0.32 0.13 314 0.29 0.16 1 / 3 0.24 0.14 0.31 1/1 7/10 0.33 0.31 0.16 1 / 3 0.30 0.16 2/5 0.15 0.30 2/3
Location 2V. Vert ical Component. Hal*ay D m Face of Dam
0.08 t o 0.13 ' 0.30 4/5 0.31 0.14 1 / 3 0.29 O.lb 5/8 0.33 0.14 1 /2 0.30 0.14 1 / 3 0.30 0.14 2/5 0.29 0.14 1/1
Minor peak a t 0.56 sec
Minor peak a t 0.19 sec
Location 3R. Radial Component. Near Toe of Dam
Observed 0.052 3 0.13 0.20 0.31 5 /6 1 / 2 22 . 0.039 3 0.27 0.24 0 . 9 1/1 2/3 Minor peak a t 0.49 sec
Observed
Observed 0.051 22 0.032
0.050 28 23 0.046 25 0.039 26 0.032
Location 3V. Vertical Comonent. Near Toe of Dam
Relatively minor peak a t 0.51 sec
l / b 3/4
Location 5R. Radial Component. Alluvium
0.52 3/5 1 / 2 'I4 Minor spikes present 9/10
1 0.30 4 0.19 t o 0.23 0.28 0.32 2 / 3 112 . Fourth. peak a t 0.49 sec 2 0.19 0.31 9/10 Tvo minor Desks a t 0.24
and 0.47-sec 27 0.061 3 0.15 0.35 0.27 8/10 1 /2 Minor peak
Location 5V. Vert ical Component. Alluvium
Observed 0.088 2 0.08 t o 0.4 0.29 1/2 22 0.061 3 0.29 0.13 0.20 9/10 8/10
0.072 2 0.14 t o 0.19 0. Y 1 / 2 24 23 0.092 2 0.32 0.14 3/10
0.063 4 0.22 0.29 0.24 1/1 Fourth peak a t 0.14 sec 26 25 0.050 3 0.19 0.14 0.28 'I1 3/4 '2/3 27 0.069 2 0.14 t o 0.19 0.31 1 / 2
SCALE Or NlLLS
KEY MAC
.LOCATION MAP
RIFLE GAP DAM
PLATE I
C Crest o f dom... ... J I
J Riprop on
10 LLLLLLW.1
0 M 100 a I belor E L 5910
S C I L L O F FEE1
M A X I M U M S E C T I O N
E M B A N K M E N T E X P L A N A T I O N Cloy, silt. sand ond qrorel compacted by tompinq rol lers t o 6 -inch layers. ,
11 Cloy, si l t , sond,qrovrl and cobblts tomllortcd by tompinq rallcrs b Q- lnm Iayers, 8 @ Miscelloneour clor. s r l t , sond. grovel. ond cobbles or rock fropments compocled .
by tomplnp r o l l e r s t o 12-inch l o p r s .
@ Selected sond,qravel ond cobbles or r ock t rogmrnts p l o r t d in 2,. Inch loyerr.
GENERAL PLAN AND SECTION
RIFLE GAP DAM
D H 2 2 a L O w , I * l .
S A N D . F l N E W l T H L I T T L E C L A V . L O O S E L Y P A C K E D . T A N
2 0
21 ' -36 ' G R A V E L A N 0 C L A V . S I L T Y . W l T H L E N S E S O F S A N D A N D G R A V E L L O O S E T O M E D I U M D E N S I T Y
.o
S I L T Y . G R A Y . C O N S I S T E N C Y I S S T I F F
I , D E N S I T V
ee.-a!o C L A Y ; S I L T Y . MEDIUM' CONSISTENCY
a o a,,?
1 .11 01 ' -94 ' S A N D . F l N E W I T H S O M E C L A V : M E O l U M C O N S I S T E N C Y
ma , 94 ' -100 ' G R A V E L . e O U L D E R S . A N D S A N D . D E N S E T O V E R Y D E N S E OW
12-#B-a.
N O T E : A L L M A T E R I A L F R O M 0-100' A R E S T R E A M C H A N N E L A N D F L O O D PLAIN DEPOSITS. N X C S 0-100.. ALTERNATING W A S H AND D R I V E S A M P L E S .
NOTE: SEE P L A T E 4 FOR BORING LOCATIONS.
!
PLATE 3 \
t
O H 2 1 . I L O W I I ~ ~ .
0 t o r o eo EL 5861.2
N O T E : N I S I Z E H O L E . N I C S 0-100' . D R I V E S A M P L E S 0-55.. A N D 80'-01)'. W A S H S A M P L E S 51'-80' .
BORING LOGS HOLES DH21 AND OH22
4
1 PLATE 4
*
. . L O C 5 AND 6
C Crest of d o m - . .
L O C 1 AND 7 -cres t €1.5978
set t lement potnt (projected1
M A X I M U M S E C T I O N
NOTE: LOCATION 4 IS OFFSET 560 FT EAST OF A L I N E THROUGH L O C 1. AN0 LOC 3 A T E L 5878.81.
L O C A T I O N S O F M O T I O N M E A S U R I N G
S T A T I O N S i
ASSUMED PROFILE OF FOUNDATION SOILS
PLATE 5
L O G OF
W T p --- -- - 2 0
4 0
I- LL
f 6 0 - a. W 0
80
I00
120-
BORING DESCRIPTION 0;-
SAND (120 PCF)
SAND, GRAVEL, BOULDERS (130 PCF)
- SILTY CLAY (125 PCF)
- C L A Y (125 PCF)
GRAVEL, BOULDERS (130 P C F )
I
CLAY (125 PCF)
-
GRAVEL, SAND, BOULDERS (135PCF)
-
BEDROCK
POISSON'S RAT I 0 0 . 4 0
PLATE 6
S H E A R WAVE V E L O C I T Y , FT/SEC
SHEAR WAVE VELOCITY PROFILE FOR THE FOUNDATION
VIE RATORY T E S T DATA
00 1000
Q
9
n "
0
800 700 800 0
1100
-
0
0
20
40
F LL
C
6 0 - F Q W 0
80
100
120
P c - -
0
PLATE 7
-
I800 0
2 0
4 0 .
6 0 , I- LL - I + n W n
8 0
100
I 2 0
140
SHEAR WAVE VELOCITY PROFILE FOR THE
FOUNDATION RAY LE IGH WAVE DISPERSION
DATA
S H E A R WAVE VE L O C I T Y , FT/SEC 6 0 0
*
R - l FROM R - 2 FROM S E I S M I C L l N E 5 - 2, S E E A P P E N D I X 0
-
1 2 0 0 800
&
S E I S M I C
1000
L I N E S - I , SEE
1400
2 7 2 0 rA
R - 2
1 6 0 0
- -
R-l
A P P E N D I X D %?a
S H E A R MODULUS, K S F I
LEGEND
- V I B R A T O R Y D A T A --- RAY L E I G H D I S P E R S I O N D A T A
/ / IN / RANGE FOR e = 0.9 e = 0.4, O C R K = I, - MATERIAL PROPERTIES IN PLATE 5
FOUNDATION S H E A R MODULUS COMPARISONS
PLATE 8
PLATE 9
J
SHEAR MODULUS, KSF
0
2 0
4 0 I- LL - I C Q W 0
6 0
80
100
SHEAR MODULUS VS DEPTH OF F O U N D A T I O N AT CENTER LINE OF D A M
8 3 4 5
\
6 7
.
b
SHEAR WAVE VELOCITY , FT/SEC 2 0 0 0
0 0
20 -
40 LL
I-- m W a U
6 0 0 J W rn
x C a W
80
100
1 2 0
SHEAR WAVE VELOCITY PROFILE FOR
THE EMBANKMENT VIBRATORY TEST DATA
PLATE 10
4 0 0 800 1200 I 6 0 0
\
\
1
/
1 .o
* I- z - 2 ,
a 0.8 a u z a a 0 a ' W 0 I 11 0 . 6 "'F
.a 2 V)
D L " : 0.4
a n 0 0 1 1 a a a 4 0 . 2 W W I I IJl v,
0 10-4 10-3 10-2 10-1 I
S H E A R S T R A I N 7 , . PERCENT
VARIATION OF SHEAR MODULUS WITH SHEAR STRAIN FOR SANDS
A F T E R R E F 4
28- /
/ /'
2 4
2 0
z W U
F a
a I a 0
I 0-4 10-3 1 0 - 2 10-1 I SHEAR STRAIN, PERCENT
DAMPING RATIOS FOR SANDS AFTER REF 4
0 10 - 4 10-3 10-2 1 0 - 1 I 10
S H E A R S T R A I N Y , P E R C E N T
TYPICAL REDUCTION OF SHEAR MODULUS WITH SHEAR STRAIN
FOR SATURATED CLAYS AFTER REF 4
b
I
35
3 0
25
I- z W U K
2 2 0 . 0 I- < E
0 15
Z 0 x 4 0
10
5
0
.
/ . /
, /'I . , /
----- 1 0 - 4 1 0 - 3 10-2 10-1 I I' o
SHEAR STRAIN, PERCENT
DAMPING RATIOS FOR SATURATED CLAYS
AFTER REF 4
UPSTREAM + I 1
0 DOWNSTREAM
FINITE ELEMENT MESH FOR 20 ANALYSIS AND LOCATIONS OF
MEASUREMENT STATIONS
I PLATE I5
PLATE 16
I
0 3 5
0 30
0 2 5 0,
2' 0 - k Q a W J 0 20 W U U 4 W V) Z 0 a y, 0.15. I W CK
L u W a
0 10-
I 0 05 - I
I
0 0 0 2 0 4 0 6 0 8 10
PERIOD, SEC
RESPONSE SPECTRA FOR I D LUMPED-MASS ANALYSIS
CASES I AND 5
y*CASE /
7
I CASZ 5
I \ I I
PLATE 17
2
0 3 5 r
0 30
0 2 5 [r,
2' 0 - I- u [I W 1 020. W U U 4 W m z 0 a m 0 15. W &
K u W a
0.10 \
'y CASE 2
/ - OBSERVED
I
I f\ \ 1 I
4 0 6 0 8 10
1 ' I I \ I /
f
0 05
0 ,
PERIOD, SEC
OBSERVED AND COMPUTED I D RESPONSE SPECTRA
C A S E 2
w
\ \ f I v l \ I
\$J
0 0.2 0
PLATE 18
I
_ . I . . . . = . . . . . _ . _ . - 7 = -7- 7 7 - - ..=--:- -7' - i-- . = _ . C : - - = > - -z-;. . %. .: z-- i .... .- i__- .;
- - - - - - - . . - . _ _ - . - - A. A - A - A 4
10
PERIOD, SEC
COMPUTED I D RESPONSE SPECTRA,
CASES 3 A N D 6
- 0 35
0 30
0 25 0,
z' 0 - 4 a W J 0 20 W U U a W V) z 0 0. y, 0.15 n W I \ (t y-CASE 6 s u W 0.
0. I 0
0 0 5 . /
\ -- -- -- 0 -
0 0.2 0.4 0 8 0 8
-
,CASE 3
. 0 35
0 30
0 25 0,
2' 0 - C a a W A 0 20 W V U Q --OBSERVED W V) z 0 a , / C A S E 6 y, 0 15' W a s a W a
0 I 0
0 05 J
\ .- -- * -\, 0
0 0 2 0 4 0 8 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED I D RESPONSE SPECTRA
C A S E 6
PLATE 19
0 35
0 3 0 -
0 25 IJ)
z' 0 - F 4 (I W J 0 20 W u u 4 W v, Z 0 a. y, 0 15, n W a f -2 W n
0 I0
0 05 -
0 0 0 2 0 4 0 8 0 8 10
PERIOD, SEC
COMPUTED I D RESPONSE SPECTRA
CASES 6 AND 8
LEGEND
SHEAR MODULUS, KSF
-- CASE' 3 -- - CASE 6 - CASE 8
NOTE: MODULUS MODIFIED' FOR SHEAR STRAIN.
5
PLATE 21
- 1
SHEAR MODULUS PROFILE MODIFIED FOR SHEAR STRAIN
0 -
2 0 .
4 0
LL
L
x l- a. W 0
6 0 ,
80
I OD L.
0 I 2
\ 1
I I
3
-- -4-
4
PLATE 22
i s
0 35.
0 30
0 2 5 m
2' 0 - I- u a W J 0 2 0 , W u V Q. W cn z 0 0. y, 0 1 5 , W LL
f 4 W a.
0 10,
O B S E R V E D
I
I
:y ! \,
I j \ v t 1,
I
\
0
'.
I /
I-' I
0 05 I
0 0 2 0 4 0 6 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED I D RESPONSE SPECTRA
CASE 8
0.
1
PLATE 23
3 - 0 35
0 30
0 2 5 . m
2' 0 - I- a a W _t 0 20 W U U Q W m z 0 a y, 0 1 5 . W
i l ,
' 1 I I
I I
' I I I I l 1 1 1 1 ! I I I ' I I I I I ' I I I I t ! !
lx L a w - OBSERVED a
0 I0
0 05
0 0 0 2 0 4 0 6 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED I D RESPONSE SPECTRA
C A S E 14
PLATE 24
PLATE 25
-
-
.O
0.3 5
0.30
0.25
rn
9 0 . - I- 4 [I W J 0.20 W u V u W ul '. Z ,CASE 2 0 a y, 0 . 1 5 - W ( t .
e . u W CL -CASE 20
0 . 1 0 .
0.05 -
\ -- 0
0 0.2 0.4 . 0.8
COMPUTED I D RESPONSE SPECTRA
CASES 2 AND 20
7
---- 0.8 I
PERIOD, SEC
L
0 35
0 30
0.25 D
2' 0 - I- u a W J 0 2 0 W U V u W V) z 0 a cn 0 15 W Q
f a W Q
0. I 0
0 0 5
0 0 0.2 0 4 0 6 0 8 1 0
PERIOD, SEC
COMPARISON OF I D AND 2 D RESPONSE SPECTRA
LOCATION 5 RADIAL COMPONENT
CASES 4 AND 2 2
. 0.35
0.30
0.2 5 m
2- 0 - + a a W J 0.20 W 0 U a W i n . z 0 0. y, 0.15 W a L a W a.
0. I 0
0.0 5
0 0 0.2 0.4 0 .8 ' 0.8 1 .O
PERIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCATION I RADIAL C O M P O N E N T
CASE 23
PLATE 27
PLATE 28
4
0 35
0 30
0 2 5 m I I
I \
2' I I 0 - I + a a
W V
W m OBSERVED z
W a s 4 W a
0 - 0 0 2 0 4 0 8 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCATION I VERTICAL COMPONENT
CASE 23
- I,
I
p, I' 'I I I
' I I I I \ I \ I I
2
/'
PLATE 29
h
0 . 3 5
0.30
0.2 5 0,
z' 0 - +
I u a W J 0.20 I
W v
V 4 W ul Z 0 a y, 0 . 1 5 I 1 ' W 1 a I z I u I \ W- 0. \
\ \ \
0.1 0' \ &--0BSf RVED
\ n
0 . 0 5
0 0 0.2 0.4 0 . 8 0 .8 1 .O
PERIOD, S E C
. OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCAT ION 2 ' RADIAL C O M P O N E N T
CASE 2 3 C
r. A
PLATE 30
0 3 5 1
0 3 0 ,
0 2 5
n,
2' 0 - I- a a W J 0 2 0 W w U a W
'\ , ' \ I \
I \ I I
. I \
I m z 0 I a 1 m 0 1 5 , W (r
s a W a -OBSERVED
0 10
0 05
0 0 0 2 0 4 0 8 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCAT ION 2 VERT ICAL COMPONENT
CASE 23 ,
I \ / -CASE 23
0 35
0 30
0 2 5 0,
2' 0 - C u a W J 0 20 W U U u W V) z 0 a. y, 0 15 W a z a W a
0 I 0
0 0 5
0 0 0.2 0 4 0 . 8 0 8 10
PERIOD, SEC I
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCATION 3 RADIAL COMPONENT.
C A S E 23 >
PLATE 31
. -
10
0 35*
0 3 0
0 2 5 0)
2' 0 - C 4 a W J 0 2 0
PLATE 32
^ . _ _ _ _ _ _ _. _ . _. . -- _ _ _ _ _ . . - . _ _-- - -.- -. -. - . .- . - . - - --. .._--. - _/ -._ .... . -..- - _. - - - - - - - & L A - - & - & &
1111111111111111111llllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllmlllllllllllttttttttmttttttttttt~~~~~~~~w"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCAT l O N 3 VE RT I C A L COMPONENT
CASE 23
- ,'l
1 l I I I I
I Ij,;
W V U 4 W V) z -CASE 23 0 n V) 0 1 5 , W (L:
< a W (1 -OBSERVED
0. I 0
0 .05 ;J
0 0 0 .2 0 4 0 6 0 8
P E R I O D , S E C
PLATE 33
4
0.35
0.30
0.2 5
-
0
2' 0 OBSERVED - I- < a W _r 0.20 W U U < W ln z 0 P cn 0.15 W a * a W a .
0. I0
0.05 \ \
-- 0 ' 0 0.2 0.4 0.8 0.8 I .O
PERIOD, SEC
OBSERVED ANDCOMPUTED 2 D RESPONSE SPECTRA
L O C A T I O N 5 RADIAL C O M P O N E N T
C A S E 23
PLATE 34
- _ . __ . _ _ _ _ _ _ _ . __ _ . - - ..I _ I . _ . _----- - <. - _ .- . . ._- __ _ _:_ _ _. - - ..C - . .- .. - - - - - -L - 4 - - . - - -. A & - -
10
0 3 5
PERIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCAT ION 5 VERTICAL COMPONENT
CASE 23 L
3
0 30 I
0 2 5 m
z' 0 - l- a a W J 0 20 W U U a W m Z I 0 I a Y, 0 15
I I
W a I
s a W a
0 I 0
0 0 5
0 0 0.2 0 4 0 8 0
)
-.------- 8
PLATE 35
L
0.35.
0.30
0.2 5 (T,
z' 0 - I-
.
-
d a W J 0.20 1
W u u d
W m z 0 n m 0.15 W I\ 1 a I I
I I ' s Q
I . I W
I I a 9,' +-CASE 26
I !! I
0. I 0 I 6' I /
1
; I
b
/ 1
. \(\, , 0.05
\ \ '..
-- ----, 0' 0 0.2 0.4 0.6 0.8 1
PERIOD, SEC :O
OBSERVED. AND COMPUTED 2 D RESPONSE SPECTRA
L O C A T ION 3 RADIAL C O M P O N E N T
C A S E 26
PLATE 36
4
0 35
0 3 0 ,
025 0,
2' 0 - k a n W J 0 2 0
-
-
f-'\ I' ! ', I I
W U
I I U a W -CASE 26
W a. - OBSERVED
\ \ \
0.05 /! \ \
0 0 0 2 0 4 0 8 0 8 10
PERIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCAT ION 3 VERTICAL COMPONENT
CASE 26 6
PLATE 37
h
0 35
0 30
0 2 5 . 0,
z' 0 - I- < a W J 0 2 0 , W U U < W ul Z 0 [L y, 0 15 W a z 4 W a
0. I 0
0.05
0 0
-
I' I \
1 I I
I L' I I N '"'
-
0.2 0.4 0 8 0 8 10 PERIOD, SEC
COMPUTED 2 D RESPONSE SPECTRA
LOCATION 5 RADIAL COMPONENT
CASES 23 AND 27
PLATE 38
2
0 3 5 r
0 30
CASE 27
0 2 5 , [T,
z' 0 - I- 4 a W _J 0 2 0 W U U a W m Z 0 Q. m 0 15 W
1
(t
YZ a W a
0 1 0 ,
0 05
0'
PERIOD, SEC
COMPUTED 2 D RESPONSE SPECTRA
LOCATION 5 VE R T I C A L COMPONENT
CASES 23 AND 27 L
I I
10
- 8 0 0 0 2 0 4 0
- 8
0.35
0.30
0.25
cn
2' 0 - I- 4 a . W
0.20 W V U a W V) z 0 (L y, 0.15 W a ' L a W Q
0. I 0
0.05
0 0 0.2 0.4 0 .6 0.8 1 .O
P E R I O D , SEC
OBSERVED AND COMPUTED 2 0 RESPONSE SPECTRA
L O C A T I O N 2 '
R A D I A L COMPONENT C A S E 27
2
17 \
-- OBSERVED
PLATE 39
r
0 3 5
0 30
0 2 5 m
2' 0 - I- 4 a W _1 0 2 0 - W U U ?
- OBSER YE D Q W cn z 0 0. I y, 0 15 W a s Q W (L
0 -
0 0 2 0 4 0 6 0 8 10
PEBIOD, SEC
OBSERVED AND COMPUTED 2 D RESPONSE SPECTRA
LOCATION 2 VERTICAL COMPONENT
CASE 27 &
PLATE 40
This page intentionally left blank
This page intentionally left blank
1. The f i r s t 6 sec o f motion h i s t o r y f o r t h e r a d i a l and v e r t i c a l
, components are shown i n p l a t e s A l through A10 f o r l o c a t i o n s 1 through 5 ,
respect ively; acce le ra t ion response s p e c t r a a r e a l s o shown i n these
p l a t e s . Pla tes A l l and A12 show t h e observed r a d i a l and v e r t i c a l motion
h i s t o r i e s from PVT l oca t ions 6 and 7. The r a d i a l components were mea-
sured hor izontal ly and perpendicular t o t h e a x i s of t h e dam; t r ansve r se
. motion components were measured ho r i zon ta l l y and p a r a l l e l t o t h e axis of
the dam and are reported i n re fe rence 2. The a c c e l e r a t i o n h i s t o r i e s
have been modified f o r base- l ine s h i f t wi th a parabol ic cor rec t ion .
They have a lso been i n t e g r a t e d t o produce ve loc i ty and displacement
h i s t o r i e s .
2. A response spectrum is t h e maximum response of a single-degree-
of-freedom system t o an acce l e r a t i on h i s t o r y , a s i l l u s t r a t e d i n f i g . A l .
In t h i s case, the spec t r a a r e p l o t t e d as curves of maximum acce l e r a t i on
versus na tura l period T f o r a value of damping D . By varying t h e
values of T and D , a complete s e t of curves is developed. A re-
sponse spectrum can be used a s a veh ic l e t o compare t he frequency con-
t e n t of various motion h i s t o r i e s . The r e l a t i v e ve loc i ty and r e l a t i v e
displacement response s p e c t r a have been computed and a r e ava i l ab l e from
WES bu t a re not presented he re in .
w CIRCULAR FREQUENCY CURVES FOR VARIOUS D K STIFFNESS M MASS D DAMPING
U U T PERIOD <
RESPONSE SPECTRA
Fig. A l . Response spec t r a
-
0 . I I .O
0,
2' 0 + 2 0 0 . 0
J W U
< m 2 0 C .
- 0 . I < 0 . 6 u 2 . 0
w J
;I 4 9b C R I T I C A L DAMPING W
$ 0 . 4 0
I .O '0 w . u
- U
m '. E 0 2
*' 0 t t: w > 0
0.2 0.4 0.6 0.0 I .O - 1 .O .PERIOD, SEC
b. ACCELERATION RESPONSE SPECTRUM
- 2 . 0
0 . 1 NOTE: LOCATION I WAS ON THE SURFACE Of THE DAM AT THE CREST.
c I-- 2 . W
5 0
4
- a !?
- 0 . 1 MOTION HISTORY
L I I 1 I I 1 0 I .O 2 .O 3 . 0 4 . 0 5 . 0 8 . 0
AND ACCELERATION TIME, SEC RESPONSE SPECTRUM
a. MOTION HISTORY RADIAL. COMPONENT LOCATION I .
0 . 8
0)
2.
0 ; 0 . 8 LI W
J Y
U U .
6
w % CRITICAL DAMPING
":. 4 0
. n u a
0 2
0
PERIOD, SEC
b. ACCELERATION RESPONSE SPECTRUM
N O T E : LOCATION I WAS ON THE SURFACE OF THE DAM AT THE CREST.
z I-'
w
D -
6 -1
Ul - 0
- 0 . 1
6
v-
- MOTION HISTORY 1 I I I I J
5 0 8 . 0
AND ACCELERATION 0 ' I .o 2 0 3 0 4 . o
TIME, SEC RESPONSE SPECTRUM
a . ' M O T I O N HISTORY . . VERTICAL COMPONENT LOCATION I
- ~
0 I * 0 4 5
m 2'
0 t
2 O 0 38 _I w U u m
i 0
- 0 I 2 0 2 7
2 0 w J u u u % CRITICAL DAMPING < w
$ 0 1 8
1 0 L "7 w
u a
u Ln , r o 09
> 0 t - u 0, >
0 0 0 2 0 4 0 6 0 8
- I 0 I 0
PERIOD, SEC
b ACCELERATION RESPONSE SPECTRUM
- 2 0
0 1 -
z I-'
$' w o u 6 _I
"l - a
- 0 I
NOTE LOCATION 2 WAS ON THE DOWNSTREAM FACE OF DAM
- MOTION HISTORY I I I I I
0 J
I 0 2 0 3 0 4 0 5 0 6 0 AND ACCELERATION
TIME, sEc RESPONSE SPECTRUM a MOTION HISTORY RADIAL COMPONENT
LOCATION 2
. 1 . 0 -
0 . 8 -
m 2'
0 'i o . e - u
0.2 0.4 0.6 . 0.8 I .o
PERIOD. SEC
b. ACCELERATION RESPONSE SPECTRUM
NOTE: LOCATION 2 WAS ON THC DOWNSTREAM FACE OF DAM. 0 . I r
E . I--
w . 5 0 ,
Q
a I? 0
- 0 . 1
MOTION HISTORY - I I I I I I
0 I . O 3 0 4 . 0 .5 0 6 . 0
AND ACCELERATION * O .
TIME, SEC RESPONSE SPECTRUM
a. MOTION HISTORY VERTICAL COMPONENT LOCATION 2
r 0 1 I 0
m 2 0 b
, l o 0 8
J W U
U <
m
i 0
- 0 I 2 0 6
2 0 W J Y U U 6
u Ln
2 0 4 0 a % CRIT ICAL DAMPING
1 0 'n u
u u
W
, 0 2 Z
> 0 C u 0
w > 0
0 0 2 0 1 0 6 0 8 1 0
- I 0 PERIOD, SEC
b ACCELERATION RESPONSE SPECTRUM
- 2 0
0 1 - NOTE LOCATION 3 WAS NEAR TOE OF DAM
z
6 J
'n - a
- 0 I
MOT1 ON HISTORY -
I I I I I I AND ACCELERATION 0 1 0 2 0 3 0 4 0 5 0 6 0
TIME, SEC RESPONSE SPECTRUM
a MOTION HISTORY RADIAL COMPONENT LOCATION 3
. 0 . I I . O
0
1' 0 b-
2 O 0 . 8
J u U U m
2 0
- 0 . 1 t 0 . 8 Q
2 . 0 u J u U U
u 0 . 4
I . O 0
LA W
U a
u 96 CRITICAL DAMPING
' z 0 . 2
>' 0 t
0, >
0 0.2 0 .4 , 0.6 0 . 8 I .O
- I 0 t PERIOD. SEC
b. ACCELERATION RESPONSE SPECTRUM
- 2 . 0 NOTE: LOCATION 3 WAS NEAR TOE oc DAM.
0 . I
3
I-'
u
J
"l - 0
- 0 . 1 , - MOTION HISTORY
I I I I I 1 0 1.0 2 . 0 3 0 4 . 0 5 . 0 8 . 0
AND ACCELERATION TIME, SEC RESPONSE SPECTRUM
a. MOTION HISTORY. VERTICAL COMPONENT LOCATION 3
I 0 1
0
2'
0 + 2 0
J w
U U
- 0 I
2 0
1 0 % C R I T I C A L D A M P I N G
U W "7 , z > 0 .+ - u
2 W
> 0 0 2 0 4 0.8 0 8 1 0
- I 0 P E R I O D . SEC
b ACCELERATION RESPONSE SPECTRUM
- 2 0 N O T E L O C A T I O N 4 WAS IN THE GATE CHAMBER
0 l r
I
*- w Z w 0 . U
J
"7 - 0
- 0 I
- - MOTION HISTORY L 1 I I I I I 0 1 0 2 0 3 0 4 0 5 0 6 0
AND ACCELERATION TIME, SEC
RESPONSE SPECTRUM a MOTION HISTORY RADIAL COMPONENT
LOCATION 4
0 1 0 35
0
2' 0 $ O 0 28
J Y
u U m
2 0
- 0 I 2 0 2 1 I
2 0 Y J Y
U d
Y r 0 1 4 0
1 0 a ul Y
U
a % CRITICAL DAMPING
"l
2 0 07
2' 0 E U
J Y >
0 0 2 D d 0 I 0 8 1 0
- I 0 PERIOD. SEC
b ACCELERATION RESPONSE SPECTRUM
- 2 0 NOTE LOCATION 4 WAS IN THE GATE CHAMBER
0 1 -
z I--
: Id o 4 J a "l - 0
- 0 I
-- AA-- V
- MOTION HISTORY L I 1 I I I I 0 1 0 2 0 3 0 4 0 5 0 6 0
AND ACCELERATION T IUC, SCC RESPONSE SPECTRUM
a MOTION HISTORY VERTICAL COMPONENT LOCATION 4
- 0 0.2 0.4 0.6 0 .0 1.0 . PERIOD, SEC
b. ACCELERATION RESPONSE SPECTRUM
- 0 . l L I 1 1 I I 1 I 0 1.0 2 . 0 3.0 4 . O 5 .0 0 . 0
TIME, SEC
a. MOTION HISTORY
MOTION HISTORY AND ACCELERATION
RESPONSE SPECTRUM RADIAL COMPONENT
LOCATION 5
0 1 1 . 0
111
2'
0 k
d 0 0 . 8
J Y
U u m
2 0
- 0 . 1 : 0 . 6 u
2 . 0 u J
Y 4 u
0 . 4
I . O 0 n In W
U a
Y % CRITICAL DAMPING "7 " Z 0 2
> 0 t 0
Y >
0 0.2 0.4 0 .6 0 . 8 I .O - 1 . o PERIOD. SEC
b. ACCELERATION RESPONSE SPECTRUM
- 2 . 0
0 . I
z e'
W
I u 0 U 6 J n "l - 0
- 0 . 1 MOTION HISTORY
I I I I I I I 0 1.0 2 0 3 0 4 . 0 5 0 6 .O
AND ACCELERATION TIME, scc RESPONSE SPECTRUM
a. MOTION HISTORY VERTICAL COMPONENT LOCATION 5
NOTE: LOCATION 5 WAS ON THE SURFACE OF THE ALLUVIAL VALLEY.
PLATE All
I
0
- I
2 U) ' - 2 z D-‘ RADIAL COMPONENT !z 0
S 2 W >
I
I 1 I I I
- -
0 -A- . v
- l o I I I I I I 2 3 4 5 6
T IME, SEC
VERTICAL COMPONENT
N O T E : L O C A T I O N 6 W A S ADJACENT TO L O C A T I O N 5 (ON T H E SURFACE O F T H E A L L U V I A L V A L L E Y A P P R O X I M A T E L Y 5 0 0 F T D O W N S T R E A M F R O M L O C A T I O N 3 )
MOTION HISTORIES LOCATION 6
L
I
0
- I
U W V)
' - 2 z >- RADIAL COMPONENT k U
9 W >
0
- I
-2 0 I 2 3 . 4 5 6
T I ME, SEC
VERTICAL COMPONENT
NOTE : L O C A T I O N 7 WAS AT A S E T T L E M E N T MARKER, 2OOFT WEST OF LOCATION I, O N T H E SURFACE' OF T H E D A M AT THE CREST.
MOTION HISTORIES LOCATION 7
,
PLATE A12
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Response spec t ra as defined i n Appendix A a r e shown i n p l a t e B 1
for t h e observed motion a t loca t ion 5 R , which i s t h e r a d i a l component of
acce lera t ion on the alluvium over 500 f t downstream from Ri f l e Gap Dam.
Acceleration response spec t r a computed from the 1D analyses fo r t h e var-
ious cases invest igated a r e shown i n p l a t e s ~ 2 - ~ 6 . Spect ra l damping i n * .
a l l p l a t e s i s 5 percent.
I
0 . 2 5
0 2 0
0 15
0 . 1 0
0 0 5
0
CASE 1, 8 0 F T TO BEDROCK CASE 2, 85 FT T O BEDROCK
0 2 5
0 2 0 m i 0 2 0 I S W J w LJ
. Y 0 l o
Z 0 L VI w a
0 0 5
0
CASE 3. 9 0 F T TO BEDROCK 0 0 2 0 4 0 6 0 8 1 0
PERIOD. T, SEC
CASE 4, 100 FT TO BEDROCK
LEGEND -- OBSERVED AT LOCATION 5 - COMPUTED NOTE' MATERIAL ASSUMED TO BE SAND.
SHEAR MODULUS C FROM VIBRATORY FIELD METHOD WAS USED I N COMPUTATIONS. SIX SEC OF HORIZONTAL INPUT MOTION.
ACCELERATION RESPONSE PERIOD, T, SEC SPECTRA FROM 10
CASE 5, 110 F T TO BEDROCK LUMPED-MASS ANALYSES CASES 1, 2, 3, 4, A N D 5
PLATE 81
J
0 0 . 2 0 . 4 0 . 6 0 . 8 "%bl PERIOD, 1.0 T, 0 SEC 0 . 2 0 . 4 0 .8 0 . 8 1 . 0
CASE 6, 9 0 F T TO BEDROCK CASE 7, 110 FT TO BEDROCK
LEGEND -- OBSERVED AT LOCATION L)
COMPUTED ACCELERATION RESPONSE NOTE: MATERIAL ASSUMED TO BE CLAY. SPECTRA FROM I D
SHEAR MODULUS C USED IN COMPUTATIONS SIX SEC OF HORIZONTAL INPUT MOTION.
LUMPED-MASS ANALYSES CASES 6 AND 7
A
I 4 r l \ ! \
I I I ' * , I
Y 4, I I
0 . 2 5
z 0 Q V) W a
0 0 5
1- -- 0
0 . 2 0
rn
z 0 2 0 . 1 5 a W 2 W U U 4
W a 0 . 1 0 I 11
\
* I I
1 I
+
#
0 2 5
0 20
0 I 5
0 10
0 0 5 m
i 2 I- : 0 W
A W U U
CASE 8, 80 FT TO BEDROCK CASE 9, 9 0 FT TO BEDROCK
1 0 0 0.2 0.4 0.8 0.8 1.0 PERIOD, 1, SEC
CASE 10, 100 FT TO BEDROCK CASE 1 1 , 110 FT TO BEDROCK
LEGEND -- OBSERVED AT LOCATION 5 COMPUTED
NOTE MATERIAL ASSUMED T O BE SAND AND CLAY MIXED. CLAY MODULUS C MULTIPLIED BY 1875 . SIX SEC OF HORIZONTAL INPUT USED.
ACCELERATION RESPONSE SPECTRA FROM I D
LUMPED-MASS ANALYSES CASES 8, 9, 10, AND I I
b
PLATE 83
0 0. Z 0.4 '0.6 0.8 1.0 PERIOO, T. SEC
CASE 12, SIX SECONDS OF INPUT
LEGEND --- OBSERVED AT LOCATION 5
- COMPUTED
NOTE: MATERIAL ASSUMED TO BE SAND AND CLAY MIXED. CLAY SHEAR MODULUS G MULTIPLIED BY 1.875. DEPTH TO BEDROCK IS 110 FT.
ACCELERATION RESPONSE SPECTRA FROM ID LUMPED
PERIOD, T, SEC MASS ANALYSES CASE 13. TWELVE SECONDS OF INPUT CASES 1 1 , 12, AND 13 ' ,
PLATE 85
0.2 5
0 . 2 0
0 . 1 5
0 . 1 0
0 . 0 5 - z P 5 : O J CASE 19, 80 FT OF LAYERED W U PERIOD, T, SEC U 4 SAND A N D CLAY CASE 20, 85 FT OF SAND w 0 . 2 5 In z 0 P VI
W a
0 2 0
0 . 1 5 L E G E N D
--- OBSERVED AT LOCATION 5 - COMPUTED
0 . 1 0 NOTE: SHEAR MODULUS C FROM VIBRATORY FIELD METHOD WAS USED IN COMPUTATIONS. o.05sj
OO 0 . 2 0 . 4 0 . 6 0.8 1 .O PERIOD, T, SEC
CASE 2 1, 85 F T OF SAND
ACCELERATION RESPONSE SPECTRA FROM ID FOURIER
ANALYSIS METHOD CASES 19, 20, AND 2 1
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The response spec t r a , as defined i n Appendix A , are given i n t h e
. p la t e s l i s t e d below f o r t h e computed and observed responses of t h e mea-
surement. loca t ions a t R i f l e Gap Dam. The computed spec t r a a re from the
2D analyses, and spec t r a l damping i n a l l p l a t e s i s 5 percent.
Location
1R
1 V
2R
2v
3R
3v
5R
5v .
Pla te
C 1
C 2
C 3
c 4
c 5
c 6
c7 c8
PLATE C1
PLATE C2
I
n
MOOULI=l.5 C
I I I! ,], I
CASE 22 CASE 23 CASE 2 4 w u 100-FT FOUNDATION 100-FT FOUNDATION 100 - F T FOUNDATION u ( 0.50 W "l j DAMPING RE-
/ ' DUCEO TO $ 0 f w . a 0.45 - ...-&loF
i ! 20.40---i W a i l i ! I 0 35 - I .
I
I
!
0
0 '
PERIOD, SEC
CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDAT ION 1 0 0 - F T FOUNDATION
LEGEND ---- OBSERVED
ACCELERATION RESPONSE COMPUTED SPECTRA FROM .
NOTE: SHEAR MODULUS C F R O M VIBRATORY F I E L D TECHNIQUE. SAND FOUNDATION
2 D ANALYSIS WITH 120-FT CLAY EMBANKMENT. VERTICAL COMPONENT
LOCATION I *
! MODUL1=0.5 G
! j I --
1 i
.J -. I I I
. I --TT, I I
J CASE 22 CASE 23 CASE 24 W U u 100-FT FOUNDATION 100-FT FOUNDATION 100-FT FOUNDATION
0.50- I W "7 i DAMPING RE- DAM MOOUL I = 2 . 5 C z ; DUCED TO $ ! 1 ' FOUNDATION MODULI = 1.5 G 0
0.45---.+ . - ,OF CASE 22 . i I i W
a 1 I j 1 I I ! 5 0 . 4 0 - --t
W i P
I ! , 0 3 5 . - 1 I --+-I
! . .
I i
I I ' 0 30--- L -
0 . 2 5 . - -. -. : - - - - . . . -- -- -. - - - -
. . . - . . . - - - - -
PERIOD, SEC
CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 109 - FT FOUNDAT ION
LEGEND ---- OBSERVED ACCELERATION RESPONSE
COMPUTED SPECTRA FROM NOTE: SHEAR MODULUS C FROM VIBRATORY
FIELD TECHNIQUE. SAND FOUNDATION 2 D ANALYSIS
WITH 120-FT CLAY EMBANKMENT. RADIAL COMPONENT LOCATION 2
PLATE C3
CASE 22 100-FT FOUNDATION
PERIOD, SEC
CASE 25 100-FT FOUNDATION
LEGEND ---- OBSERVED
COMPUTED
NOTE: SHEAR M O D U L U S G F R O M VIBRATORY F I E L D TECHNIQUE. SAND FOUNDATION WITH 120-FT CLAY EMBANKMENT.
CASE 26 8 0 - F T FOUNDATION
CASE 27 100-FT FOUNDATION
ACCELERATION RESPONSE SPECTRA FROM 2 D ANALYSIS
VERTICAL COMPONENT LOCATION 2 .
PLATE c4
0 . 4 5
0 :40
-' 0 . 3 5
0 . 3 0
0 . 2 5 3 -.t- . - ' - ! 1 i
0 . 2 0
0 . I 5
0 . 1 0
b
Z-0.05 2 l-
a u o J W CASE 22 CASE 23 CASE 2 4 u u 100-FT FOUNDATION 100-FT FOUNDATION 1 0 0 - F T FOUNDATION ( 0.50" Y I I VI z i i 1 DAMP&G RE- I
i I DAM MODULI = 2 . 5 G'
, DUCED TO $ , FOUNDATION MOOULI = 1.5 G 0 % 0 . 4 5 -- -OF CASE. 2 2
! I I I
Y I a
x i j 0 . 4 0
W a.
---- --- . 7--
PERIOD, SEC
CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 100-FT FOUNDAT ION
L E G E N D
---- OBSERVED ACCELERATION RESPONSE COMPUTED SPECTRA FROM
NOTE: SHEAR MODULUS G FROM VIBRATORY FIELD TECHNIQUE. SAND FOUNDATION
2 D ANALYSIS WITH 120-FT CLAY CM~ANBMENT. RADIAL COMPONENT
LOCATION 3 ,
PERIOD, SEC
CASE 25 100-FT FOUNDATION
LEGEND ---- OBSERVED
COMPUTED
NOTE: SHEAR MODULUS C FROM VIBRATORY FIELD TECHNIQUE. SAND FOUNDATION WITH 120-FT CLAY EMBANKMENT.
CASE 26 8 0 - F T FOUNDATION
CASE 27 100-FT FOUNDATION
ACCELERATION RESPONSE SPECTRA FROM 2 D ANALYSIS
RADIAL COMPONENT LOCATION 5
I I
PLATE C7
4
CASE 24
'0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 0 0 . 2 0 . 1 0.6 0 . 8 1.0
PERIOD, SEC
CASE 25 CASE 26 CASE 27 100-FT FOUNDATION 8 0 - F T FOUNDATION 100 - F T FOUNDAT ION
LEGEND ---- OBSERVED
COMPUTED ACCELERATION RESPONSE
SPECTRA FROM NOTE: SHEAR M O D U L U S C F R O M VIBRATORY
FIELD TECHNIQUE. SAND FOUNDATION 2 D ANALYSIS WITH 120-FT CLAY EMBANKMENT. VERTICAL COMPONENT
LOCAT ION 5
PLATE ~8
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APPENDIX D: SEISMIC FIELD STUDY \
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DEPARTMENT OF THE ARMY WATERWAYS EXPERIMENT STAT ION. CORPS OF ENGINEERS
P. 0. BOX 631
VICKSBURG. MISSISSIPPI 39180
IN RCCLV ~ c r s n TO, WESSD 31 March 1971
MEMORANDUM FOR RECORD
SUBJECT: Seismic Fie ld Study, R i f l e Gap Dam, R i f l e , Colorado,, 16-28 November ,1970
1. A seismic f i e l d study was conducted a t R i f l e Gap Dam n e a r R i f l e , Colorado, during the pe r iod 16-28 November 1970. This f i e l d s t u d y con- s i s t e d of conventional s u r f a c e v i b r a t o r y and r e f r a c t i o n seismic t e s t s . I n add i t ion t o these t e s t s , a n o t h e r seismic t e s t was conducted i n which t h e Rayleigh wave t r a i n w a s recorded. f i e purpose of t h e s e tests w a s t o provide seismic information r e l a t i v e t o s o i l c o n d i t i o n s and e l a s t i c p roper t i e s wi th in t h e Rifle Gap Dam and o f t h e foundat ion on t h e down- stream s i d e of t h e dam. S p e c i f i c a l l y , - compress i o n w a v e v e l o c i t i e s , depth t o in te r faces , bedrock c o n f i g u r a t i o n , and s h e a r wave v e l o c i t i e s a s a function of depth were t o b e determined from t h e f i e l d s tudy. An- o ther purpose of t h e se ismic tests, i n which t h e Rayleigh wave t r a i n was recorded was t o determine Rayleigh wave v e l o c i t i e s wi th depth (Rayleigh wave d i spers ion method) s o t h a t a' comparison and e v a l u a t i o n o f d a t a could be m d e between t h e Rayleigh wave d i s p e r s i o n method and t h e sur-- face v ibra tory method.
2 . Messrs. F. K. Chang, M. M. Carlson, and J. R. Curro, Jr., v i s i t e d t h e s i t e t o perform the s u b j e c t s t u d y . P r i o r t o a r r i v i n g a t t h e test s i t e , mechanical d i f f i c u l t i e s were encountered wi th t h e ins t rumenta t ion vehic le i n Denver and Fr isco , Colorado. These mechanical breakdowns caused a time l o s s of some f o u r days. When t h e ins t rumenta t ion v e h i c l e was repaired, Messrs. Chang and Curro .proceeded t o Grand Junct ion, Colorado, t o meet with o u r con tac t , M r . B i l l McCleneghan, Bureau o f Reclamation. M r . Carlson drove t h e ins t rumenta t ion v e h i c l e t o t h e Rifle Gap Dam test s i t e . M r . McCleneghan was presenTed wi th a p l a n o f t e s t s which were t o be performed a t t h e test s i t e . He approved t h e p l a n of t e s t s , bu t s t i p u l a t e d t h a t charge s i z e s be l i m i t e d t o 2 l b and deto- nated i n shotholes l e s s t h a n 5 f t deep. He a l s o r e q u e s t e d t h a t any ho les caused by t h e de tona t ion o f exp los ives b e b a c k f i l l e d . During t h e course of conversation, M r . Curro asked about w a t e r l e v e l s in piezom- e t e r s t h a t were located on t h e downstream s i d e o f t h e dam abou t 100 ft from the toe . M r . McCleneghan s t a t e d t h a t approximately s i x weeks p r i o r t o 20 November, a l l piezometer p i p e s were overflowing. At t h e present time (20 ~ovember) , water l e v e l s i n t h e p iezometers were a b o u t 2-3 ft above t h e ground s u r f a c e toward t h e west end o f t h e dam and 2-3 ft below t h e ground surface toward t h e e a s t end o f t h e dam.
WES SD 3 1 March 1971 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,
16-28 November 1970
M r . McCleneghan a l s o obta ined. permiss i o n from t h e Colorado S t a t e ' High- way Department f o r t h e conduct o f a ' v i b r a t o r y t e s t on S t a t e Highway 325 which t r a v e r s e s t h e c r e s t o f t h e dam.
3. A f t e r meeting w i t h M r . McCleneghan, t h e WES c o n t i n g e n t went t o t h e R i f l e Gap Dam t e s t site, m e t M r . C a r l s o q and made a v i s u a l reconnais- s a n c e o f t h e s i t e . No seepage from t h e embankment and no p i p i n g o r sand b o i l s from t h e founda t ion were observed. M r . S. W. GUY, Instrumen- t a t i o n Branch, WES; jo ined t h e f i e l d p a r t y 20 November f o r t h e conduct of t h e v i b r a t o r y tests and r e t u r n e d t o WES on 23 November.
4 . Seven r e f r a c t i o n s e i s m i c t r a v e r s e s , seven seismic t r a v e r s e s f o r t h e Rayleigh wave d i s p e r s i o n method, and t h r e e v i b r a t o r y t r a v e r s e s were run a t t h e R i f l e Gap D a m site'. R e f r a c t i o n se ismic . t r a v e r s e s S-1 through S-6 are shown i n I n c l 1 and S-7 is shown i n I n c l 2. The se i smic t r a - v e r s e s f o r t h e Rayleigh wave d i s p e r s i o n method were l o c a t e d i n t h e same p o s i t i o n as t h e r e f r a c t i o n seismic t r a v e r s e s . The v i b r a t o r y t r a v e r s e s (V-1 through V-3). were l o c a t e d as shown i n I n c l 3.
5. The d a t a obta ined from t h e r e f r a c t i o n s e i s m i c tests ( t r a v e r s e s S-1 through S-7) are shown i n t h e t i m e ve r sus d i s t a n c e p l o t s , I n c l s 4-7. The t i m e ve r sus d i s t a n c e p l o t s were used t o c o n s t r u c t subsur face p r o f i l e s f o r t h e s e i s m i c d a t a . The subsur face p r o f i l e is shown in I n c l 8 f o r t r a v e r s e s S-1 and S-2, i n I n c l 9 f o r t r a v e r s e s . S - 3 and S-4, and i n I n c l 10 f o r t r a v e r s e s S-5 and S-6. A s u b s u r f a c e p r o f i l e f o r t r a v e r s e S-7 cou ld n o t be c o n s t r u c t e d because it was s h o t i n on ly one d i r e c t i o n .
6. The seismic d a t a ( I n c l s 7-10) i n d i c a t e d one minor and t h r e e major v e l o c i t y zones. The minor v e l o c i t y zone was n e a r t h e s u r f a c e of t h e ground w i t h a maximum t h i c k n e s s o f 4 f t and had v e l o c i t i e s t h a t ranged from 1000 t o 1200 f p s . The thre; major v e l o c i t y zones were, 1400 t o 2500 f p s w i t h a maximum t h i c k n e s s o f abou t 37 f t , 4800 t o 8600 fps with a maximum t h i c k n e s s of about 116 f t , and 10,800 t o 12,500 f p s f o r t h e bedrock v e l o c i t y zone. Bedrock w a s encountered a t a maximum depth of 130 f t below t h e ground surface.
7. Data ob ta ined from t h e v i b r a t o r y t r a v e r s e s are p l o t t e d a s number of waves ve r sus d i s t a n c e from which s h e a r (Rayleigh) wave v e l o c i t i e s a r e determined. These p l o t s a r e shown f o r t r a v e r s e s V-1 through V-3 i n I n c l s 11-13, r e s p e c t i v e l y . From t h e d a t a t a k e n from t h e number of waves ve r sus d i s t a n c e p l o t s , surface wave v e l o c i t y is simply ca lcu la ted a s wavelength times frequency. Assuming t h a t t h e surface wave ve loc i ty is e q u a l t o t h e s h e a r wave v e l o c i t y and is a p p l i c a b l e a t . a depth equal t o one-hal f t h e wavelength, p l o t s o f s h e a r wave v e l o c i t y v e r s u s depth were prepared f o r t r a v e r s e s V-1 through V-3, as shown i n I n c l s 14-16, r e s p e c t i v e l y . For t r a v e r s e V-1, t h e s h e a r wave v e l o c i t y g e n e r a l l y
, WESSD 3 1 March 1 9 7 1 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,
16-28 November 1970
increased from 560 f p s a t a depth o f 7 f t t o 750 f p s a t 93.5 ft. A s l i g h t l y lower v e l o c i t y o f 495 fps a t a depth of 11 ft was noted. The shear wave v e l o c i t y f o r t r a v e r s e V-2 i n c r e a s e d from 625 fps a t a depth of 6.5 f t t o 1085 f p s a t 108.5 ft. The s h e a r wave v e l o c i t y f o r t r a v e r s e
.V-3 increased from 700 f p s a t a depth o f 7 f t t o 960 f p s a t 32 ft, t h e n showed a s h a r p decrease i n v e l o c i t y t o 805 f p s a t 33.5 f t . The s h e a r wave v e l o c i t y inc reased a g a i n t o 1090 f p s a t 90 f t . The d a t a p o i n t s a t 97 f t and 117.5 ft are q u e s t i o n a b l e because o f s i g n a l q u a l i t y . .
8. The p l o t s of s h e a r modulus, .G , v e r s u s depth f o r t r a v e r s e s V-1 through V-3 a r e shown in I n c l s 17-19, r e s p e c t i v e l y . Shear modulus is equal t o t h e s h e a r wave v e l o c i t y squared t i m e s t h e mass d e n s i t y . For t r a v e r s e s V - 1 and V-2, a wet u n i t weight o f 120 p c f w a s used above 50 ft and 130 pcf below 50 ft. For t r a v e r s e V-3, a w e t u n i t weight o f 135 pcf was used f o r a l l depths. The s h e a r modulus ranged from 63,50 p s i t o 33,800 p s i a s shown i n I n c l s 17-19.
9. Only t h e r e s u l t s of t h e Rayle igh wave v e l o c i t y s e i s m i c tests con- ducted a long t r a v e r s e s S-1 and S-2 and a l o n g t r a v e r s e S-7 are p r e s e n t e d i n t h i s memorandum. The o t h e r two se i smic tests c rossed over a c r e e k about 1 0 f t deep and t h e Rayleigh wave energy was n o t w e l l d e t e c t e d which may i n d i c a t e t h a t a t r e n c h could be d e t r i m e n t a l t o t h e normal propagation o f Rayleigh wave energy. There were a l s o o t h e r problems encountered i n ob ta in ing good d a t a from t h e Rayleigh wave d i s p e r s i o n seismic t e s t s . The most d i f f i c u l t problem was o b t a i n i n g usab le ampli- tudes o f t h e Rayleigh wave t r a i n . Ampl i f i e r g a i n s a r e c r i t c a l and must be ad jus ted f o r a p a r t i c u l a r charge s i z e . If t h e g a i n s a r e t o o high, t h e d a t a traces w i l l exceed t h e osc i l logram width and b e l o s t . Con- versely, i f t h e g a i n s are t o o low, t h e Rayleigh wave train w i l l n o t b e detec ted . This procedure caused a number o f s h o t s t o b e repea ted . Another problem is t h e e r r o r in t roduced i n t h e d a t a caused by s h o o t i n g i n or n e a r t h e o r i g i n a l d i s t u r b e d shothole . When t h e i n i t i a l charge is detonated, it produces a c a v i t y i n t h e s3i1, thus caus ing a n o t h e r charge detonated i n t h e same sho tho le t o produce d a t a somewhat d i f f e r e n t from t h e o r i g i n a l sho t .
10 . The r e s u l t s o f t h e Rayleigh wave seismic t e s t a long t r a v e r s e s S-1 and S-2 a r e shown i n I n c l 20 a l o n g wi th t h e d a t a from v i b r a t o r y tra- verse V-1. . The Rayleigh wave v e l o c i t y from t h i s t e s t is determined a s t h e d i s t a n c e between two geophones d ivided b y t h e , t i m e r e q u i r e d t o t r a v e l between t h e same two geophones. The Rayleigh wave v e l o c i t i e s a r e abou t two t o t h r e e t imes h i g h e r t h a n t h e s h e a r wave v e l o c i t i e s determined from t h e v i b r a t o r y d a t a . It should b e no ted t h a t d a t a from two bor ing l o g s have been included i n I n c l 20. Data from bor ing DH21, which i n d i c a t e s two d i s t . i n c t boundar ies a t depths of 56 and 84 ft,
' WESSD 3 1 March 1970 SUBJECT: Seismic F i e l d Study, R i f l e Gap Dam, R i f l e , Colorado,
16-28 November 1970
c o r r e l a t e w e l l w i t h t h e Rayleigh wave v e l o c i t y p r o f i l e . However, o t h e r b o r i n g s i n t h e a r e a , such as bor ing DH22 ( I n c l 20), i n d i c a t e a d i f f e r ence as r e g a r d s dep ths a t which certain materials a r e encountered. The r e s u l t s of t h e Rayleigh wave seismic test a l o n g t r a v e r s e S-7, which w a s s h o t up t h e f a c e o f t h e dam, i n d i c a t e d t h a t t h e d i r e c t compression and s h e a r wave v e l o c i t i e s ob ta ined were 4000 and 1900 fps, r e s p e c t i v e l y , f o r t h e embankment as shown in I n c l 21. The average s h e a r wave v e l o c i t y determined from t h e v i b r a t o r y d a t a ( t r a v e r s e V-3) was a b o u t 900 fps and t h e compression-wave v e l o c i t y was 4800 f p s from t r a v e r s e S-7.
' 11. Thus f a r , r easons f o r d i f f e r e n c e s between s u r f a c e , v i b r a t o r y , and Rayleigh wave d i s p e r s i o n d a t a have n o t been determined. It is suggested t h a t t h e v i b r a t o r y s h e a r wave v e l o c i t y d a t a b e used as a lower bound .
and t h e maximum Rayle igh wave v e l o c i t y d a t a b e used as t h e upper bound ' f o r t h e m a t e r i a l p r o p e r t y d e s c r i p t i o n .
2 1 I n c l as
CF w/ i n c l : M r . S. J. Johnson
J. R. CURRO, JR. Geophys ic is t Vibra to ry Loads S e c t i o n
S R I O Shotpoint
Seismic traverse no. and d i rec t ion 1" = 2 00 '
SEISMIC T!ST LAYOUT Rifle Gap Dam, Colorado
Inclosure 1
o Shotpoint X Geophones
1"= 100 f t . S5ISP;IC TEST WYOiJT Traverse 5-7 (up face of d m ) Rifle Gap Dam, Colorado
1 Inclosure 2
8 Vibrator l oca t ion VIBRATCISY mT LAYOUT Vibration t r ave r se no. and d i r ec t ion Z f l e Gap Dam, Colorado
1" = 200 f t .
Inc losure 3
H
2 t-' 0
F ID
Traverses S-1 and S-2 I
.STANCZ and S-4
0 Traverse S-5 X Traverse S-6
Distance, ft. TIMIX versus DISTANCE Traverses S-5 and S-6
H : t-' 0
; iD , . . . . , .
1,; , , , / > ,- .;I.:: ijl~;~:~?~~''~: 'Ti ' ..::::.i.: ;-7 (up face of dam)
Zast , Distance . f t .
APPR0XC;AT:I PROFILE OF SUBSURFACE !~IATUIIAIS Traverses S-1 and S-2
North, Distance, ft.
APPROXS34ATE PROFILE OF SUBSURFACE NATERIALS Traverses S-3 and S-4
I .' H s 0
I I-' 0
I :
E m I-' 0
I '
APPltOl!llihTiS PROl"'CL2 31: SUElmI?AC:< ilATXR1I;LS Traverses S-5 and S-6
Inclosure 11
Inclosure 12
Inclosure 13
Velocity, f p s
SHZAR dAVZ VZLOCITY versus DEPTH
Traverse V-1 Yest 6
Velocity, fps
SHEAR HAVE VEI.OCITY versus DSPTH
Traverse V-2 North
Inclosure 16
3 Shear Moduli. 10 psi
10 '15 29 25 3,O Shear doduli, ld kips/sq. d. I 2.L 1 3.2 1 L.0 I
SHEAR MODULI versus DEPTH Traverse V-1
3 Shear Moduli, 10 osi 20 I
30
SHEllR MODULI versus DEPTH Traverse V-2
3 Shear Moduli, 10 psi
SHEAR I*IODULI versus DEPTH Traverse V-3
Comparison Of Kayleigh Wave Velocities versus Depth(along Traverses ,S-1 and S-2) and Shear Wave Velocities versus Depth(Traverse V-1)
TDU versus 'DISTANCE Rayleigh Wave Seismic ~ e s t ( u p face of dam)
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Unclass i f ied . . security C l a s s i f i c a t i o n
I DOCUMENT CONTROL DATA - R 6 D . 1 (S.~,,,I~~ c ~ r ~ ~ r l l c = t r o n of tltl*. body 01 =barrrct and Ind.xln# .nnot=t lm muat & .nt.r*d when the o.~~.II r.por~ 1, clm..lllrd,
' I . OR0,GlNATlNG A C T I V I T V fCO)PO.*t* *"thol) Ir. R E P O R T SKCURITV CLASSICICATION
U. S. Army Engineer Waterways Experiment S ta t ion ~ n c l a s s ' i f i ed Vicksburg, Miss iss ippi ~ b . GIOUP
I 3 . R E P O R T T I T L E EARTHQUAKE: RESISTANCE OF EARTH AND ROCK-FILL DAMS; Report 2, ANALYSIS OF RESPONSE OF RIFLE GAP DAM TO PROJECT RULISON UNDERGROUND NUCLEAR DETONATION
m. OESCIIPTIVL NOTES f f lp . 01 t*pcat a d I n c l u ~ l ~ * d.t*o)
Report 2 of a s e r i e s 5 . ~ u ~ u o R t l 1 (F1t.1 nome. middle Inltl*l. 1a.t n*m*J
James E. Ahlberg Jack Fowler Lyman W. Heller
8. R E P O R T O A T E 7.. T O T A L ' W O . O F P A C K S 7b. NO. O C R L C S
June 1972 132 10 or. C O N T R A C T 01 G R A N T NO. 9.. ORIOINATOR.S R E P O R T NUMLIISI
b. P R O J E C T N O . I, Miscellaneous Paper S-71-17, Report 2
C. ob. O T u L R n L P o l l T NOIS I (Any other numb.- h.t .ur & r**[email protected] thl* npon)
d.
10. D I S T R I B U T I O N S T A T E Y C N T
Approved fo r pub l ic r e l e a s e ; d i s t r i b u t i o n unlimited.
I I S U P P L E Y L N T A R V N O T E S II. S P O N S O R I N G Y I L I T A R V A C T I V I T V
Office , Chief of Engineers, U. S. Amy Washington, D. C .
The motion of R i f l e Gap Dam w a s measured i n September 1969 during the Project RULISON underground nuclear explosion. The observed response w a s then compared with t h e re- sponse computed i n a mathematical model. Observed and computed responses were s i m i l a r . From t h i s study it appears t h a t t h e mathematical models used a re applicable t o t h e de- s ign and analysis of s o i l s t r u c t u r e s , a t l e a s t f o r ground motion in tens i t i e s comparable t o those observed a t R i f l e Gap D m .
I I m C L A C C m 00 C O I Y 1.7.. I J A N S1. W W I C I I. DD ,'27,,1473 o m s o L m y m .om Am-* urn.. Unclassified
Security C l ~ ~ ~ i f i c ~ t i o n . .
Unclassified
Unclassified Security CIsaaification .
Security Classification
I a. K C V W 0 1 1 0 S
'
Earth dams
Earthquake-resistant structures
Ground motion
Mathematical models
Nuclear explosion effects
Rifle Gap Dam
Rock-fill dams
Rulison (h-o ject )
Underground explosions
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