pffitL*iTffin--{rTiil4 Jsltfatarr lserrgaJian poiiteknik EXAMINATION AND EVALUATION DIVISION DEPARTMENT OF POLYTECHNIC EDUCATION (MINISTRY OF HIGHER EDUCATION) CIUL ENGINEERING DEPARTMENT FINAL EXAMINATION DECEMBER 201O SESSION C4008: GEOTECHNIC 2 DATE : 18 APRIL 2011 (MONDAY) DTIRATION : 2 HOIIRS( 8.30am - t0.30am) This paper consists of SEVEN (7) pages including the front page. Stlucture / Essay ( 6 questions - answer 4 questions). CONFIDENTIAL TINTIL 18 APRIL 2O1I DO NOT OPEN THIS QUESTION PAPDR UI-{TIL INSTRUCTED BY TIIE CHIEF INWGILATOR
EXAMINATION AND EVALUATION DIVISIONDEPARTMENT OF POLYTECHNIC EDUCATION
(MINISTRY OF HIGHER EDUCATION)
CIUL ENGINEERING DEPARTMENT
FINAL EXAMINATIONDECEMBER 201O SESSION
C4008: GEOTECHNIC 2
DATE : 18 APRIL 2011 (MONDAY)DTIRATION : 2 HOIIRS( 8.30am - t0.30am)
This paper consists of SEVEN (7) pages including the front page.Stlucture / Essay ( 6 questions - answer 4 questions).
CONFIDENTIAL TINTIL 18 APRIL 2O1IDO NOT OPEN THIS QUESTION PAPDR UI-{TIL INSTRUCTED BY TIIE
CHIEF INWGILATOR
CONFIDENTIAL
QUESTTON I
C4OO8- GEOTECHNIC 2
Figure I shows a cross section of sheet pile. construct a flow net for the sheet pileusing scale 1 :100. Then determine the total seepage for the sheet pile in m3/day/mIength if the coefficient of permeabilify given is 3.7 x l0-3 nrm/s. calculate the porewater pressure at point M and point N.
Water Level
Water Level
1.2m
4.5m
Figure 1
(25 marks)
Ground Level
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CONFIDENTIAL
QUESTION 2
C4OO8-GEOTECIINIC 2
Fig,re 2 shows a homogeneous earth dam resting on an impervious base. Givenk:2.33 x l0-a cm/s
i. Drau, the flow net through earth dam without filter.
(20 rnarks)
ii. Calculate the quantity of seepage in nr3/hour/m length.
(5 marks)
Figure 2
Not to scale
Table 2: Correction table for earth dam without filter
Slope, o 30 60 90 120 150 180
Laa+Aa
437 432 0.25 0.1 8 0.10 0
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CONFIDENTIAL
QUESTTON 3
C4OO8- GEOTECHNIC 2
A concrete retaining wail with a smooth verticar back supports a 5 m depth of soir,comprising of two layers.
(a) calculate the active pressure behind the wall and draw the lateral earth pressuredistribution behind the wall.
( 9 marks )
(b) calculate the resultant active thrust acting on the wall and its location for thefollowing groundwater level conditions.
( l6 marks )
Figure 3
@=30o
Y = 19.2 kNlm3
Y,ot = 2O.6 kN/m3
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CONFIDENTTAL
QUESTTON 4
C4OO8_ GEOTECHNIC 2
calculate and check the stabilify of a backfilled masonry wall with the height of 9.0rr, crest width of I.2
'r and base width of 4.0 m. The back of a retaining wail isverlical and the backfilled surface is horizontal. The soil will be surcharged 60kN/m2as shown in Figure 4. Given :
The ultimate bearing capacity is 600kN/m2.
y :20kN/m3
c' :0
d' :4oo ,
6:200
.<- 4.0m --) 7*. . )1 N/,r'
( 25 marks )
Figure 4
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CONFIDENTIAL
QUESTTON s
C4OO8- GEOTECHNIC 2
a) By using suitabre diagrams, state THREE (3) types of srope fairure.
(6 rnarks)
b) For the slope shown in Figure 5 below, find the factor of safety against sliding forthe trial slide surface pe. use the Feilenius Srice Method of EIGHT (g) srices.(Use scaie of 2cm: im).
(19 marks)
R :9m
C :15 kN/m2y : 20kN/m3
0 : t00
Figure 5
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CONFIDENTIAL
QUESTIOI\I6
C4OO8_ GEOTECHNIC 2
a) Define consolidation in geotechnics.
(4 marks)
b) Explain the consolidation concept based on the Spring concept with the aid ofsuitable diagram.
(8 marks)
c) l) A 3m thick layer (double drainage) ofsaturated clay under a surcharge
Ioading completed 90% of (Tv) primary consoridation in 75 days. Find theconsolidation coefficient ofclay for the pressure range.
(6 marks)
ii) Ass,ming a 30rnm thick undisturbed cray sampre as described in questionc (i), how long will it take to complete 90o/o of theconsolidation in thelaboratory for simirar consoridation pressure range. The raboratory testsample will have two_way drainage.
