Earthpressures 2013 Updated

7/23/2019 Earthpressures 2013 Updated

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Geotechnical Engineering Research Laboratory Samuel G. Paikowsky, Sc.D One University Avenue Professor Lowell, Massachusetts 01854Tel: (978) 934-2277 Fax: (978) 934-3046e-mail: [email protected] site: http://www.uml.edu/research_labs/Geotechnical_Engineering/

DEPARTMENT OF CIVIL ANDENVIRONMENTAL ENGINEERING

14.533 ADVANCED FOUNDATION ENGINEERING

SAMUEL G. PAIKOWSKY

2013CLASS NOTES

EARTH PRESSURES

At Rest Lateral Pressure Rankine Active and Passive Earth Pressure States Relations Between Earth Pressures and Wall Movements DIA Dual Interfacial Apparatus Interfacial Friction and Adhesion Active and Passive Earth Pressure Coefficients Computation of a General Active Case Horizontal Pressure from Surface Loads Effect of Ground Water and Filter on Wall Pressures Earth Pressure due to Compaction Earth Pressure on Rigid Retaining Walls Near Rock Faces


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PAGE 1

EARTH PRESSURES

Review Ch. 6 in H.Y. Fang, Foundation Engineering Handbook orCh. 11 in J.E. Bowles, Foundation Analysis and Design (5 th ed.) or

Ch 7 in B.M. Das Foundation Engineering (7th

ed.)

Design of earth-retaining structures requires knowledge of the earth,water, and external loads that will be exerted on the structures.

AT REST LATERAL PRESSURE

(a) Theoretical elasticity under conditions of lateral zero disp. (referring toeffective stresses).

(1) 1322 1 E

(2) 21331

E

for zero lateral yield 3 = 2 = 0

for orthotropic or oedometer conditions

2 3

(1) + (2) 323 22

13 1

131

K = h/ v = 3/ 1

1o

K say = 0.15 K o = 0.18

= 0.30 K o = 0.43= 0.50 K o = 1.00


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PAGE 2

(b) Empirical Correlations After Mayne & Kulhawy (1982)

min

maxmax

v

OCR

maxOCR

Reloading (empirical)

maxsin1

maxo OCR

OCR 1

43

OCR OCR

sin1K

UnloadingO.C. OCR = OCR max Ko = (1-sin ') OCR sin '

Virgin loading

N.C. OCR = OCR max = 1 Ko = (1-sin ') (Jacky, 1944)

References:Mayne, P., and Kulhawy, F. (1982). "K o-OCR Relationships in Soil", Journal of the

Geotechnical Engineering Division , ASCE, Vol. 108, GT6, pp. 851-872.Kulhawy, F., and Mayne, P. (1990). Manual on Estimating of Soil Properties for

Foundation Design, Electric Power Research Institute Report EPRI EL-6800, Palo Alto, CA.

VirginLoading

FirstUnloading

FirstReloading

h

max

min


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PAGE 3

maxr 1

maxonc0 OCR

OCR 1m

OCR OCR

K K

Kulhawy & Mayne (1990)

Substituting (see below) K onc = 1 - sin , = 1-K onc 1 - = 1 - sin , m r = 0.75

brings to the equation previously presented

Konc = (1 - sin tc) 0.1(range)


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PAGE 4

= (1 K onc ) 0.1(range)

m r = 0.75


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PAGE 5

Vertical Stress vs. Horizontal Stress in K o Test on Ottawa SandTest Results from unpublished data, Y.G. Lu and S.G. Paikowsky.

0 20 40 60 80

Lateral Stress, h (kPa)

0

30

60

90

120

150

180

V e r

t i c a

l S t r e s s ,

v ( k P a

)

0 20 40 60 80

0

30

60

90

120

150

180Theoretical values using the general equation(Mayne and Kulhawy, 1982) and frictionalangle obtained from direct shear tests.Testing data obtained by using Tekscan sensor 6300#1Testing data obtained by using Tekscan sensor FlexiForce (average of six single sensors)Testing data obtained by using Tekscan sensor 1230 (average of two single sensors)

Amherst Test Equipment for K o Measurement with UML Measuring DeviceStrain Gage

Oedometer

Tekscan Sensor

Material: DryOttawa Sand

= 16.8 kN/m 3

= 39


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PAGE 6

RANKINE ACTIVE & PASSIVE EARTH PRESSURE STATES

Basic Assumptions (i) The soil is in a state of plastic equilibrium according to Mohr

Coulomb Rigid body translation(ii) There is no friction or adhesion along the wall, principle stressesorientation remain the same as in the soil.

Frictional Material (Cohesionless)

Active:

sin1sin1

245tan2

aK ah K

Passive:

sin1

sin1

245tan 2

pK

ph K

Example: = 30 o Ko 0.5, K a = 1/3, K p = 3

3

1

45 + /2

f p

1

3

45 - /2

f p

3 = Ka v 1a = 3P = v h=Kp v= 13 = h = K o v

45- /2

passive stateof stressactive

failure planefailure plane

P Pat rest K 0

45+ /2


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PAGE 7

Material with Cohesion (Active)

aaa K C K h 21

p p p K C2K h

Ka aK

ha = A = v tan 2(45- /2) - 2C tan(45 - /2) = v Ka - 2c aK

Ka = tan 2 (45- /2)

Zc = 2c/ Ka

Figure 7.6 Rankine active pressure(pp. 298-299)

c

s = c + tan


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PAGE 8

Material with Cohesion (Passive)

Figure 7.13 Rankine passive pressure (p. 316)

p = v tan 2(45 + /2) + 2C tan(45 + /2) = v Kp + 2c Kp

Figure 7.13 (continued) (p.317)


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PAGE 9

SLOPING BACKFILL COHESIONLESS SOIL

Analyt ical So lution (Rankine) Active And Pass ive

Figure 7.8 Notations for active pressure

22

22

coscoscos

coscoscos)()(

lower upper pa K&K

= 0 Ka= tan2(45-

2) =0 KP= tan

2(45+ 2

)

For c - soil

KP ,Ka =

1

cossincosz

c8cos

zc

4coscoscos4

sincosz

c2cos2

cos

1

22

2

222

2

2


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PAGE 10

RELATIONS BETWEEN EARTH PRESSURES AND WALLMOVEMENTS

Reference: Clough, G.W. & Duncan, J.M., (1991). Earth Pressure, Chapter 6, in Found Eng. Handbok ,2nd edition, ed. Hsai-Yang Fang, Van Norstrand, Reinhold .

Type of BackfillValues of /H

Active PassiveDense Sand 0.001 0.01

Medium Dense Sand 0.002 0.02Loose Sand 0.004 0.04

Compacted Silt 0.002 0.02Compacted Lean Clay 0.01 0.055Compacted Fat Clay 0.01 0.05

Usual Range for Earth Pressure Coefficients (Bowles)Soil K A K0 KP

Cohessionless 0.22 0.33 0.4 0.6 3 14Cohessive 0.50 1.00 0.4 0.8 1 2

Guide for Lateral Displacements for Developing Active Stresses (Bowles)Soil and Condition hA

Cohessionless Dense 0.001 to 0.002HCohessionless Loose 0.002 to 0.004H

Cohesive Firm 0.01 to 0.02HCohesive - Soft 0.02 to 0.05H


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PAGE 11

DIA DUAL INTERFACIAL APPARATUS

Reference: Paikowsky,S.G., Player,C.M., and Connors,P.J. (1995). A Dual Interface Apparatus for Testing Unrestricted Friction of Soil Along Solid Surfaces, GeotechnicalTesting Journal, June 1995, ASTM, Philadelphia, PA.

Figure 1 Solid surf ace topography and its representation through normalizedroughness.

Figure 6 Longitudinal section (B-B) of shear box and external reaction fr ame.

particle

A

A

816 mm

400 mm

front load cells

rear load cells

instrumentedfriction bar

interface plates

teflon-coatedaluminum frames

500 mm

bottom sample

top sample


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Figure 14 Grain size distribution of tested granular materials.Reference: Paikowsky,S.G., Player,C.M., and Connors,P.J. (1995). A Dual Interface Apparatus for Testing Unrestricted Friction of SSolid Surfaces, Geotechnical Testing Journal, June 1995, ASTM, Philadelphia, PA.

0.0100.1001.00010.000GRAIN SIZE (mm)

0

10

20

30

40

50

60

70

80

90

100

P E R C E N T F I N E R B Y W E I G H T ( % )

FINES (silt fine medium coarseSAND

GRAVEL

# 2 4 2 9 G

L A S S B E A D S

# 1 9 2 2

G L A S S B E A D S ( w / s )

O T T A

W A S A N D

1 m m

G L A S S B E A D S

4 m m

G L A S S B E A D S &

R O D S

N E V A D

A S A

N D

H O L L I S T O N S A N D


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PAGE 13

Reference: Paikowsky,S.G., Player,C.M., and Connors,P.J. (1995). A Dual Interface Apparatus forTesting Unrestricted Friction of Soil Along Solid Surfaces, Geotechnical Testing Journal, June 1995,

ASTM, Philadelphia, PA.

Figure 15 SEM (scanning electron microscope) images of: (a) washed andsorted No. 1922 glass beads at a magnification of X63.2, and (b) Ottawa sand at amagnification of X56.5.


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PAGE 14



Figure 16 Solid surface topography: (a) rough , (b) sand blasted, and (c)smooth.


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PAGE 15



Figure 17 Distribut ion of frict ion angles and stresses along an interface of 1-mmglass beads and various solid surfaces: (a) smooth, (b) intermediate, and (c)

rough.


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PAGE 16



Figure 25 Interfacial characterization according to zones identifies through therelations existing between average interfacial fr iction angles (measured along the

central section) of glass beads and normalized roughness.


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PAGE 17



Figure 26 The ratio of modif ied direct shear box to central section in terfacialfrict ion angles versus average normalized roughness.


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PAGE 18

Reference: Naval Facilities Engineering Command. (1986). Foundations & Earth StructuresDesign Manual 7.02, Revalidated by Change 1, September, TRC Environmental Corp.,Washington, D.C.


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E F F E C T O F F I L T E R O N L A T E R A L P R

E S S U R E

N o

F i l t e r

F u

l l H y d r o s

t a t i c P r e s s u r e

U =

( 4 x 4

) ( 5 x 7

) w

= 1 2

. 5 t


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PAGE 27


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PAGE 28

Reference: Barker, R.M., Duncan, J.M. Rojiani, K.B., Ooi, P.S.K., Tan, C.K., and KimS.G. (1991). NCHRP Report 343: Manuals for the Design of Bridge Foundations, TRB,Washington, DC, December.


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EARTH PRESSURE DUE TO COMPACTIONThe compaction induces load, unload and reload conditions. The lateral stresseswill be therefore higher than those under K o only. These stresses are usuallybeing referred to as "residual earth pressures".

Reference: Clough, G.W. & Duncan, J.M., (1991). Earth Pressure, Chapter 6, in FoundationEngineering Handbook , 2 nd edition, ed. Hsai-Yang Fang, Van Norstrand, Reinhold.


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Procedure for us ing the Charts for Earth Pressure after Compaction

1. Knowing the compaction machine, calculate compaction per length or perarea (plates or rollers).

2. Get into the right chart at the depth you are looking for find residual lateral

stress.3. Check Tables 6.4 or 6.5 for the correction factors to correct the stress youfound.

4. Make sure that your residual lateral stress K0 conditions.

Example:

Estimate the horizontal earth pressure at a depth of 5ft below the surface aftercompaction in 6in lifts by multiple passes of a Bomag BW 35 walk-behind vibratoryroller. The estimated internal friction angle is = 40 . The static weight on one drum is628lb , and the centrifugal force on one drum is 2,000lb . The length of the drum is15.4in. Thus, q = 2,628/15.4 = 171lb/in.

From Figure 6.17, at a depth of 5.0ft, find p h = 340psf.


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Adjustments must be made to this value, however, to account for the facts that: (1) the for the soil is 40 rather than the standard 35 , (2) the length of the roller is 15.4in ratherthan the standard 84in, and (3) the roller approaches within 0.2ft of the wall rather thanthe standard 0.5ft. The adjustment factors for these non-standard values are estimatedusing the values summarized in Table 6.4. The values of the adjustment factors (called

R) are: R x = 1.8, R w = 0.85, R = 1.14.

Multiplier Factors for z = Variables 2 ft 4 ft 8 ft 16 ft

Lift thickness and distance from wall ( x) (adjustments for these two factors are combined

6-inlifts

x = 0 1.70 2.00 1.90 1.85x = 0.2 ft 1.50 1.85 1.70 1.65x = 0.5 ft 1.00 1.00 1.00 1.00x = 1.0 ft 0.85 0.86 0.87 0.88

12-inlifts

x = 0 1.05 1.10 1.15 1.20x = 0.2 ft 1.00 1.05 1.10 1.10x = 0.5 ft 0.90 0.94 0.98 1.00x = 1.0 ft 0.70 0.70 0.70 0.70

Roller width ( w) w = 15 in 0.90 0.85 0.85 0.90w = 42 in 0.95 0.95 0.95 0.95

w = 84 in 1.00 1.00 1.00 1.00w = 120 in 1.00 1.00 1.00 1.00

Friction angle ( ) = 25 0.70 0.80 0.90 1.10 = 30 0.85 0.90 0.95 1.05 = 35 1.00 1.00 1.00 1.00 = 40 1.25 1.15 1.10 1.00


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Using this information from Figure 6.17 and Table 6.4, it is estimated that thepostcompaction lateral earth pressure is equal to:ph = (340psf)(1.8)(0.85)(1.14) = 590psf. This value compares to a value of 570psfcalculated by means of detailed computer analyses performed using the methodsdeveloped by Duncan and Seed (1986).

By using the same procedure to estimate pressures at other depths, the distribution ofearth pressures after compaction can be estimated. At the depth where these becomesmaller than the estimated at-rest pressures, the lateral pressures are equal to the at-rest values, as shown in Figure 6.16.

Post compaction earth pressures estimated using Figures 6.17, 6.18, and 6.19 andTables 6.4 and 6.5 apply to conditions where the wall is stiff and nonyielding. Thesepressures would provide a conservative (high) estimate of pressures on flexible walls ormassive walls whose foundation support conditions allow them to shift laterally or tiltaway from the backfill during compaction. Such movements would reduce the earth

pressures. The reduction would be expected to be less near the surface, where thecompaction-induced loads would tend to follow the wall as it deflected or yielded.


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EARTH PRESSURE ON RIGID RETAINING WALLS NEAR ROCKFACES

Reference: Frydman, S. and Keissar, I. (1987). Earth Pressure on Retaining WallsNear Rock Faces, ASCE Journal of Geotechnical Eng., V113, pp.586-599.


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Reference: Frydman, S. and Keissar, I. (1987). Earth Pressure on Retaining Walls Near Rock Faces, ASCE Journal of Geotechnical Eng., V113, pp.586-599.

1 exp 2 tan (Eq. 1)


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Equation 3:

1 1 1 4 14 1


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Conclusions

The results of a study of the lateral pressure transferred to a rigid retaining wall bygranular fill confined between the wall and an adjacent rock face are :

1. It is found that Eq. 1, commonly used for estimating lateral pressure on silo walls,may be used to calculate the pressure for the no-movement (K 0) condition, usinga K value of 1 sin . Significant variations from the estimated pressure valuemay occur next to the wall, due to small variations in placement conditions (e.g.,localized compaction effects, slight variations in density, etc.).

2. A conservative approach could be to use a decreased value in calculating K,so as to obtain an upper envelope to the expected pressure values.

3. The pressures acting on the wall, when it reaches an active condition by rotatingabout its base, appears to be less sensitive to small variations in placementconditions. Progressive failure, which occurs within the soil mass adjacent to thewall during its rotation, results in a decrease in , and this decreased value mustbe used in estimating the pressure acting on the wall.

4. Reasonable estimates of wall pressure may be obtained from application of thesilo pressure equation, in which a K-value compatible with the values of and (see Eq. 3) is used.

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