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UNIVERSITI MALAYSIA PERLISPeperiksaan Semester PertamaSidang Akademik 201112012

16 Januari 2012EAT 314 - Geotechnical Engineering[Kejuruteraan Geoteknik]

Masa: jam

Please make sure that this question paper has Eight 8) printed pages including this frontpage before you start the examination.[Sila pastikan kertas soalan ini mengandungi L P N 8) muka sural yang bercetak termasuk mukahadapan sebelum anda memulakan peperiksaan ini.]This question paper has TWO 2) sections, SECTION A and SECTION B. Answer ALLquestions from SECTION A nd ny ONE 1) question from SECTION B Each questioncontributes 20 marks.[Kertas soalan ini mengandungi DUA 2) bahagian BAHAGIAN A dan BAHAGIAN B Jawab SEMUsoalan daripada BAHAGIAN A dan mana-mana S TU 1) soalan dari B H GI N B Markah bagi tiaptiap soalan adalah 20 markakJNote: Some formulas are given in the Appendix.Nota: Beberapa rumus diberikan dalam Lampiran.

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SECTION A: This section has 4 questions. Please answer LL questions.BAHAGIAN A: Bahagian ini mengandungi 4 soalan. Silajawab SEMUA soalan.

Question 1[Soalan 1J

a) A (2 x 2 m) square footing is placed at a depth of 1.5 m below the ground surface.The subsoil consists of a sand layer with bulk unit weight of 16 k m3, saturatedunit weight of 18.8 k m3 and angle of friction, I> is 32. By using Meyerhoff sequation;[Sebuah tapak segiempat sama 2 x 2 m diletakkan pada kedalaman 1.5 m di bawah permukaantanah. Tanah bawah terdiri daripada lapisan pasir dengan berat unit pukal 6 kNlm3, berat unittepu 18.8 kNlm3 dan sudut geseran (/J ialah 32. Dengan menggunakan persamaan Meyerhoff,]i. Estimate the ultimate bearing capacity of the footing if the ground watertable is located at a depth of 5 m below the ground surface.

[Anggarkan keupayaan galas muktamad tapak tersehut jika aras air bawah tanah terletakpada kedalaman 5 m di bawah permukaan tanah.[9 Marks IMarkah]

ii. Estimate the ultimate bearing capacity of the footing if due to some reasons,the ground water table increases to the ground surface.[Anggarkan keupayaan galas muktamad tapak tersebut jika kerana beberapa sebab, arasair bawah tanah meningkat k permukaan tanah.}

[9 Marks IMarkah]

iii Compare the results to see if in this case, the position of ground water tablehas an effect on the bearing capacity of foundation.[Bandingkan keputusan untuk melihat jika da/am kes ini, kedudukan aras air bawah tanahmempunyai kesan ke atas keupayaan galas tapak.}

[2 Marks IMarkah]

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Question 2[Soa/an2]

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a) A retaining structure is supporting a 5.3 m high excavation. This wall has movedsufficiently to develop active condition. The properties of he soil behind retainingwall are c = 0, = 30, Yb = 20.4 k m3 Ysat = 22.0 k m3 The ground watertable exists at 2.5 m below ground surface. Assume that the back of the wall issmooth so that the wall friction angle, d O.[Sebuah dinding penahan menyokong pengorekan setinggi 5.3 m. Dinding ini telah bergeraksecukupnya untuk menyebabkan keadaan aktif. Ciri-ciri tanah di be/akang dinding penahanadalah c 0 c[j 3rt Yb 20.4 kNlm3 Y3OI= 22.0 kN/m3. Aras air bumi adalah 2.5 m di bawahpermukaan tanah. Anggap belakang dinding adalah licinjadi sudut geseran dinding J 0 ]1. Sketch the lateral pressure diagram.[Lakarkan gambarajah tekanan sisi.]

ii. Estimate the lateral earth pressure using Rankine s theory.[Anggarkan tekanan sis; menggunakan teori Rankine.]

[ MarkslMarkah]

[8 MarkslMarkah]

iii. Analyze the hydrostatic pressure and total horizontal pressure on the wall.[Analisa tekanan hidrostatik danjumlah tekanan sisi pada dinding.][ MarkslMarkah]

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Question[Soalan3]

a) A long natural slope in a fissured over consolidated clay is inclined at 120 to thehorizontal. The water table is roughly at the surface of the slope. A slip hasdeveloped on a plane parallel to the surface at depth of 5 m. The saturated unitweight of the clay is 20 kN/m3 and the peak strength parameters are c = 10kN/m2 and (/) = 26. Analyze the factor of safety along the slip plane.

b)

[Satu eerun semulajadi yang panjang di clalam rekahan tanah liat terkukuh menyondong padasudut 12 0 terhadap paksi mendatar. Aras air bumi seeara kasarnya beracla pada permukaaneerun. Satu gelinciran telah berlaku pada satah yang selari dengan permukaan pada kedalaman 5m Berat unit tepu untuk tanah liat adalah20 kNlm dan parameter kekuatan puneak ialahe = 10kNlm2 and (/J = 26 , Analisafaktor kese/amatan sepanjang satah gelineiran tersebut.]

[IS MarkslMarkah]

A vertical cut is to be made through a soil mass. The soil has the followingproperties; Yb= 16.5 kN/m3, c = 25 kPa and = 21 . Estimate the safe depth ofthe cut using a factor of safety =2.[Satu pemotongan menegak telah dibuat melalui jisim tanah. Tanah tersebut mempunyai eM-cir;seperti berikut: /h = 16.5 kNlmJ e = 25 kPa and (/J = 21 . Anggarkan keclalaman pemotonganselamat menggunakan faktor keselamatan= 2],[ MarkslMarkah]

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Question[Soalan4}

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a Analyse the importance o site investigation prior to any construction works.[Analisa kepentingan kajian tapak sebelum sebarang kerja pembinaan dijalankan.}

[1 arksl arkah]b The soil sample is essential for laboratory testing to determine the soil propertiesat the construction site. Classify the types o soil sample based on the required

laboratory testing. Evaluate the equipment and the procedure required to obtain agood quality undisturbed samples for laboratory testing.[Sampel tanah adalah penting untuk pengzyian makmal untuk mengetahui ciri ciri tanah ikawasan pembinaan. Kelaskan jenis jenis sampel tanah berdasarkan ujian makmal yangdiperlukan. Buat penilaian terhadap peralatan d n prosedur yang diperlukan untuk mendapatsampel tak terganggu yang berkualiti baik untuk pemeriksaan makmal.}[1 arksl arkah]

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SECTION B : This section has 2 questions. Please answer any ONE of the questions.BAHAGIANB: Bahagian ini mengandungi2 soafan. Silajawab mana - mana S TU (1) soa/an.

Question 5[Soa/an5J

a A footing is planned to support an allowable load of 1000 kN. The footing will beembedded 2.0 m below ground surface. The unit weight of soil is 16.68 kN m3and the ground water table is very deep. Terzaghi s equation for ultimate bearingcapacity, quit for square foundation is given by: quit = 1.3 cNc + qNq + OAByNy,while for circular foundation is given by: quit = 1.3 cNc qNq O.3ByNy Usefactor of safety 3.[Sebuah tapak dirancang bagi menyokong beban yang dibenarkan 1000 kN Tapak tersebutter/etak pada keda/aman 2.0 m di bawah permukaan tanak Berat unit tanah adalah 16.68 kNlm3dan aras air bawah tanah adalah sangat dalam. Persamaan Terzaghi bagi keupayaan galasmuktamad, quit bagi tapak segiempat sama diberi sebaga;: quit = 1.3 cNc qNq O.4B IN-psementara bagi tapak bu/at diberi sebaga;: qull = 1.3 cNc qNq 0.3B INy. Gunakan laktorkeselamatan 3.J1. Design the size of a circular footing if the soil is cohesive (zero angle offriction) with cohesion value of 30 kPa

[Rekabentuk saiz tapak bulat jika tanah adalah /empung sudut geseran kosong) dengannilai kejelekitan 30 kPa.J[5 Marks I Markah)

ii. Design the size ofa circular footing if he soil is granular (cohesionless) withangle of friction of40 degree.[Rekabentuk saiz tapak bu/at jika tanah adalah berbutir tiada kejelekitan) dengan sudutgeseran 40 darjah.]

[6 Marks I Markah]iii. Design the size of a square footing if the soil is cohesive (zero angle offriction) with cohesion value of 30 kPa.

[Rekabentuk saiz tapak segiempat samaj ika tanah ada/ah /empung sudut geseran kosong)dengan nitai keje/ekitan 30 kPa.][ Marks I Markah]

IV. Design the size of a square footing if the soil is granular (cohesionless) withangle of friction of40 degree.[Rekabentuk saiz tapak segiempat jika tanah ada/ah berbutir tiada kejelekitan) dengansudut geseran 40 darjah.J

[5 Marks I Markah]

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Question 6[Soalan 6}

a) A concrete pile of diameter 300 mm is to be driven into a medium dense to densesand to a depth of 7.5 m. The bulk unit weight of the soil is 20 kN/m3 Nogroundwater was encountered during site investigation. Estimate the bearingcapacity of the pile.[Satu cerucuk konkrit bergaris pusat 300 mm dipacu lee dalam sederhana padat lee pas;r padatpada leedalaman 7.5 m. Berat unit pukal tanah ialah 20 kNlm3 Air bawah tanah tidak dijumpa;semasa penyiasatan tapak Anggarkan keupayaan galas cerucuk}Assume the following:[Anggap yang berikut:]- Coefficient oflateral earth pressure K is 0.95.

[Pekali tekanan sisi bumi K ialah 0.95.]Factor of safety is 2.[Faktor leeselamatan ialah 2.}

- Critical depth is 20 times pile diameter.[Kedalaman kritikal adalah 20 kali ganda garis pusat cerucuk}

- Tan 8 for concrete against dense sand is 0045.[Tan 8 untuk konkrit terhadap pasir padat ialah 0.45.]

- Nq value is given as 60 for friction angle of 36)[Nilai Nq diberi sebaga; 60 untuk sudut geseran 36.)[10 Marks Markah]

b) A pile is to be drilled in a stiff clay deposit. The diameter of the pile is 1.05 m andthe pile is to be extended from a depth of2 m to 20 m. The undrained cohesion ofthe soil along the embedment of the pile is shown in Table 1 f the adhesionfactor, a along the pile is 004 estimate the allowable load on the pile. Use factorof safety 2.[Satu cerucuk akan digerudi dalam endapan tanah liat kukuh Garis pusat cerucuk adalah 1.05 mdan cerucuk tersebut dilanjutkan dari leedalaman 2 m hingga 20 m. Kejelekitan tidak tersalirtanah di sepanjang pembenaman cerucuk tersebut adalah seperti yang d;tunjukkan dalam Jadual1. Jika faktor rekatan, a di sepanjang cerucuk ialah 0.4 anggarkan beban yang dibenarkan leeatas cerucuk Gunafaktor leeselamatan 2.]

.... 8/-

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Depth m)[Kedalaman m)]268112141618222

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Table 1{ aduallj

46118015175111651716522

EAT314)

[1 MarkslMarkah]

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APPENDIXTable : Terzaghi Bearing Capacity Factors

N N Ny0 5 7 1 0 0 01 6 0 1.1 0 12 6 3 1 2 0 13 6 6 1 3 0 24 7.0 1.5 0 35 7 3 1 6 0 4

7 7 1 8 O S7 8 2 2 0 0 68 8 6 2 2 0 79 9 1 2 4 0 9 10 9 6 2 7 1 0

10 2 3 0 1 212 10 8 3 3 1.413 11 4 3 6 1.614 12.1 4 0 1 9IS 12 9 4 4 2 216 13 7 4 9 2 S17 14 6 5 5 2 918 15 5 6 0 3 319 16 6 6 1 3 820 11 1 1 4 4 421 18 9 8 3 5 122 20 3 9 2 5 923 21 7 10 2 6 84 23 4 11 4 7 925 25 1 12 7 9 2

26 27 1 14 2 10 727 29 2 15 9 12 528 31 6 17 8 14 629 34 2 20.0 17.130 37 2 22 5 20 131 40 4 25 3 23 732 44 0 28 S 28 033 48 1 32 2 33.334 52 6 36 S 39 635 57 8 41 4 47 336 63 S 47 2 56 737 70 1 53 8 68 138 77 S 61 S 82 339 86 0 70 6 99.840 95 7 81 3 121 5

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Table 2: Bearing Capacity Factors Meyerhoff and Brinch Hansen)2 Nc Ng Nx M> X ~ B H )0 5.14 1.00 0.00 0.001 5.38 1.09 0.00 0.002 5.63 1.20 0.01 0.013 5.90 1.31 0.02 0.034 6.19 1.43 0.04 0.055 6.49 1.57 0.07 0.096 6.81 1.72 0.11 0.147 7.16 1.88 0.15 0.198 7.53 2.06 0.21 0.279 7.92 2.25 0.28 0.3610 8.35 2.47 0.37 0.4711 8.80 2.71 0.47 0.6012 9.28 2.97 0.59 0.7513 9.81 3.26 0.74 0.9414 10.37 3.59 0.92 1.1615 10.98 3.94 1.13 1.4216 11.63 4.34 1.38 1.7217 12.34 4.77 1.66 2.0718 I3.I< 5.26 2.00 2.4919 13.93 5.80 2.40 2.9720 14.83 6.40 2.87 3.5421 15.82 7.07 3.42 4.1922 16.88 7.82 4.07 4.9623 18.05 8.66 4.82 5.8524 19.32 9.60 5.71 6.8925 20.72 10.66 6.76 8.1126 22.25 11.85 8.00 9.5327 23.94 13.20 9.46 11.1928 25.80 14.72 11.19 13.139 27.86 16.44 13.23 15.41

30 30.14 18.40 15.67 18.0831 32.67 20.63 18.56 21.2332 35.49 23.18 22.03 24.9533 38.64 26.09 26.16 29.3334 42.16 29.44 31.15 34.5335 46.12 33.30 37.16 40.7136 50.59 37.75 44.42 48.0637 55.63 42.92 53.27 56.8638 61.35 48.93 64.07 67.4039 67.87 55.96 77.34 80.1140 75.31 64.20 93.70 95.46

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5 1 15 20 25 30 35 40 45Angle o internal friction

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FORMUL

qult net) qult - q qu t - yD fqall net) =P = Fs = Fsq=r{D, - D)+r'Dr v =fyD+r'(B - D ]

s, 1 + n ~ : JSq = 1 + ~ } a n ;sr = - O . 4 ~ )e = 1 + 0 . { ~ )

dq = 1 { ~ }an; I - sin;Ydr =1ic =iq = 1- :oJ=I;)

e = 1 + 0 . 4 t a n - { ~ )dq 1 + 2 t a n ; I - s i n ; Y t a n - { ~ )dr =1

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