(COVER PAGE) Programme : Bachelor of Engineering (Hons) in Civil Engineering. Time : 8.00 am am Reading Time : Nil

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1 CVE40 (F) / Page 1 o 7 FINAL Exaination Paper (COVER PAGE) Session : MAY 011 Prograe : Bachelor o Engineering (Hons) in Civil Engineering Course : CVE40: Foundation Engineering Date o Exaination : 9 (Friday) July 011 Tie : 8.00 a a Reading Tie : Nil Duration : Hours Special Instructions : This paper consists o SIX (6) questions. Answer any FOUR (4) questions in the answer booklet provided. All questions carry equal arks. Materials peritted Materials provided : Table o Bearing Capacity Factors Variation o T v versus U Variation o N q * with L/ D Plot o Mid plane Degree o Consolidation against Tv Plot o ΔP /ΔP p Against U or various ΔP /ΔPo Noralised Side Load Transer and Base Load Transer Exainer(s) : Associate Proessor Dr Lee Sun Chai Moderator : Ir Cader Mohideen M. Aboobucker This paper consists o 7 printed pages, including the cover page.

2 CVE40 (F) / Page o 7 INTI INTERNATIONAL UNIVERSITY BACHELOR OF ENGINEERING (HONS) IN CIVIL ENGINEERING CVE 40 : FOUNDATION ENGINEERING FINAL EXAMINATION : MAY 011 SESSION This paper consists o SIX (6) questions. Answer any FOUR (4) questions in the answer booklet provided. All questions carry equal arks. Question 1 A surcharge with vertical drain installation is proposed or a KTM project to accelerate the consolidation settleent o a 18 thick clay layer underlying the construction area. In this project, preabricated vertical drains o 100 wide and 40 depth were installed with spacing (triangular pattern) o 1 to accelerate consolidation settleent o this clay layer deposit. The coeicient o consolidation or radial drainage (c vr ) is 6 per year and vertical drainage (c v ) is 3 per year. The ratio o horizontal hydraulic conductivity in the unseared to seared zone (k h /k s ) is 4.5. The diaeter o sear zone is 0.3. Assue surcharge is applied instantaneously and the soil is drained at the top and botto o the layer. (a) (b) (b) (d) Deterine the degree o consolidation o the clay layer caused only by the preabricated vertical drains ater six onth o surcharge application. (9 arks) Deterine the degree o consolidation o the clay layer that is caused by the cobination o vertical drainage and radial drainage ater six onth o surcharge application. (8 arks) Deterine the increase in degree o consolidation due to cobined vertical and radial drainage, and vertical drainage only. ( arks) Deterine the teporary surcharge that will be required to eliinate the entire priary consolidation settleent in 5 years by pre-copression technique with vertical drainage. Assue that the average eective overburden pressure at the iddle o clay layer is 10 kn/ and the increase in the pressure due to the average peranent load on the clay layer is 1 kn/. (6 arks) Ur (- 1- e 8Tr ) ; C t T ; T v v H dr U 100 v ( ) 4 n n 3 s kh n s ln ( n s s 4 4n ks n ) ln s ; U v =1-(1-U r )(1-U v ) d e n ; d w s ds d w

3 CVE40 (F) / Page 3 o 7 Question A contractor has one year tie liit contract or constructing the rat oundation or a structure. The structure can tolerate no ore than 100 o settleent. The oundation will rest on the surace o a 14--thick dense sand deposit which overlies a 16--thick deposit o norally consolidated clay (C v = 0.74 /day). Please reer to the Figure Q. (a) Calculate the net ultiate bearing capacity o soil using Meyerho Bearing capacity equation. Note that the rat is ounded below the existing ground. (7 arks) (b) Deterine the actor o saety against bearing capacity ailure. (3 arks) (c) Deterine the settleent o the rat using the :1 stress distribution ethod. (7 arks) (d) The construction tie required or the at oundation would be 6 onths. Only 6 onths (18.5 days) reains or preloading. Calculate the height o the ill that will eliinate the unwanted settleent o greater than 100. The unit weight o ill aterial is 18 kn/ 3. (6 arks) (e) List the settleent liits or the architectural daage and structural daage. ( arks) Ground Level Mediu Dense Sand γ d =16.0 kn/ 3 Mediu Dense Sand Water Table 0 40 γ sat =17.0 kn/ 3 = 3 c =0 1 Noral Consolidated Clay 16 γ sat =16 kn/ 3 G s =.75 w=60 % Liquid Liit=70% =0 c =50 kn/ ROCK Figure Q

4 CVE40 (F) / Page 4 o 7 Question 3 (a) A concrete pile o 50 diaeter is driven through a - depth granular ill placed over the sandy clay deposit o 13 in depth. The granular ill is recently placed and will settle under load. The pile is a low displaceent pile with earth pressure coeicient k=1-sin and has a soil pile interaction angle =0.60. Deterine the downdrag orce o the pile. (14 arks) L' L - H L' L - H H ' - H ' Q Ground Surace Ground water table ccc Recent Fill (Granular) γ t =18 kn/ 3, =3º, c =0 13 cccc Sandy Clay γ sat =17.81 kn/ 3, =3º, c =0 Figure Q3a (b) A 3 x 4 group o high displaceent pile with a pile spacing o 1 in the x-direction and 0.8 in the y-direction, and pile diaeter o 0.4 supports a vertical colun load o 5 kn. This pile group has an eccentricity o 0.0 in the x-direction and eccentricity o 0.10 in the y-direction as shown in Figure Q3b. Deterine the load acting on pile No., No. 10 and pile No. 1 o the pile group. (11 arks)

5 CVE40 (F) / Page 5 o 7 5 kn Figure Q3b 1 Question 4 (a) In an inrastructure project, stone coluns were adopted as the soil iproveent technique. The site investigation conducted at the project site revealed the in-situ soil is sot clay with undrained cohesion o 30 kn/. The eective radial stress as easured by pressureeters is 50 kn/. The eective riction angle o the stone is 3. (i) Deterine the allowable bearing capacity (in kn) using Hughes ethod with a saety actor o, (7 arks) (ii) Deterine the required length o stone colun to carry a design load o 100 kn assuing the load is supported erely by shat riction (8 arks) (b)deterine the iniu sae distance or heavy taping (dynaic copaction) i the tap ass o 10kN is dropped through a height o 15. (5 arks) (c) State the 5 coon pitalls when using the surcharge preloading as a ethod o soil iproveent. (5 arks)

6 CVE40 (F) / Page 6 o 7 Question 5 (a) Figure Q5(a) shows a drilled shat o 1500 in diaeter penetrating two layers o sandy soil. By using the Reese and O Neill ethod, deterine the load carrying capacity or a liiting settleent o 4. (19 arks) Q cccc Ground Surace 10 cccc Groundwater Table 8 Mediu Dense Sand sat =18 kn/ 3, N 60 below the base =50 c=0, = Figure Q5a (b) Due to space constraint at site, a 00- diaeter icropile o API pipe is to be constructed instead o pad oundation to support a design load o 300 kn. Given that outside diaeter o pipe casing=14.3, thickness=1.5 and steel grade =55N/, calculate bond length (L) i the ultiate bond strength ( s ) o the soil is 40 kn and base resistance ( b ) o 1000kN using a actor o saety o.0. Design the icropile as a riction pile. (6 arks) Question 6 A retaining wall o 7 high will be constructed with geotextile reinorceent at an intersection o a highway interchange. The backill aterial would be a copacted coarse-grained soil with t =16 kn/ 3 and =. The geotextile selected has an ultiate tensile strength o 87.5 kn/. The soil-geotextile interace riction value δ=/3φ. The insitu oundation soil has the ollowing soil properties: t =17 kn/ 3, φ=30 and c u =55 kn/.

7 CVE40 (F) / Page 7 o 7 The ollowing actors o saety (FS) are recoended: Installation daage: FS =1.0 Creep: FS = 1.5 Cheical degradation: FS=1.3 Biological degradation: FS=1.3 Geotextile reinorceent Pull-out=1.5 Geotextile reinorceent Break-out=1.5 For the design o the geotextile reinorced wall, deterine a) the vertical spacing o the geotextile (7 arks) b) the total length o reinorceent at dierent height (9 arks) c) lap length o the geotextile ( arks) d) actor o saety against overturning and sliding (7 arks) Appendix 1 Appendix Appendix 3 Appendix 4 Appendix 5 Appendix 6 Table o Bearing Capacity Factors and other related actors Variation o N q * with L/D by Coyle and Castello Plot o id-plane degree o consolidation against T v Plot o P / P p against U% or various values o P p / P o Variation o Tv* with U Noralised side load and base load transer vs. settleent or cohesionless soil ---THE END--- CVE40(F)/May 011/Assoc. Pro. Dr Lee/CA/