[3] The excavation of a construction project of a commercial building is shown in Figure 3. The following figure shows the excavation profile, with the bottom 12 m below the ground surface. The width and length of the excavation are 20 m and 30 m, respectively. The piezometer shows that the head in the gravel layer below the bottom of the cut is 7 m below the ground surface. The unit weight of water is yw = 9.8 kN/m³. Answer the following questions. 2 m 3.5 m 3.5 m 3 m A 12 m Soft clay 7 m B Ysat 18 kN/m³ Undrained shear strength C = 50 kPa 8 m Table 4.2 Bearing Capacity Factors $' No Na Ny $' N N₁₂ Ny 0 5.14 1.00 0.00 1 5.38 1.09 0.07 2 5.63 1.20 0.15 3 5.90 1.31 0.24 4 6.19 1.43 0.34 5 6.49 1.57 0.45 21 6 6.81 1.72 0.57 7 7.16 1.88 0.71 8 7.53 2.06 0.86 9 7.92 2.25 1.03 10 8.35 2.47 1.22 11 8.80 2.71 1.44 12 9.28 2.97 1.69 13 9.81 3.26 1.97 14 10.37 3.59 2.29 BERDA2222222223 16 11.63 4.34 3.06 17 12.34 4.77 3.53 18 13.10 5.26 4.07 FS= 19 13.93 5.80 4.68 20 14.83 6.40 5.39 15.82 7.07 6.20 16.88 7.82 7.13 18.05 8.66 8.20 Yay= 24 19.32 9.60 9.44 H 25 20.72 10.66 10.88 26 22.25 11.85 12.54 (A)(s²) BT if T≤B√2, B'=B/√2 if T>B/√2, B" = √2B' B" L CN. (1+0.227) (y+2) H H [4 [₁H₁ +₂H₂+...+y„H„] (C₁ +C₂)(s²) Cav= [c,H₁+c₂H₂++cH»] M M = max max 27 23.94 13.20 14.47 8 28 25.80 14.72 16.72 29 27.86 16.44 19.34 K≈ 1-sin o' 30 30.14 18.40 22.40 15 10.98 3.94 2.65 31 32.67 20.63 25.99 (continued) Table 4.2 Bearing Capacity Factors (Continued) 8 K≈0.95-sin Ko(overconsoklate) K OCR o(normally consolidated) Rankine's active earth pressure Coulomb's active earth pressure Paimax Active force Gravel (Hard Layer) Figure 3 (3.1) List briefly describe ALL of the possible failure modes of a deep excavation during construction. (3.2) Compute the strut loads in the supports. Assuming horizontal spacing between the supports is 4 m. Hint: Use the apparent earth pressure envelope developed by Peck (1969) to estimate the lateral earth pressure. (3.3) Compute the factor of safety against the bottom heave. (3.4) What type(s) of wall would you suggest for this site? Choose the appropriate one(s) and give your reasons. (a) H pile and wood lagging. (b) Steel sheet pile. (c) Diaphragm wall. (d) Continuous bored pile. Equations and Tables: qi Bearing capacity equation: q=c'N FFF+q'N FFF +0.5BN FFF Shape factors by De Beer Depth factors by Hansen (1970) (1970) F₁ =1+()) and Hanna and Meyerhof (1981) $' No Na Ny $' No N₁ Ny 32 35.49 23.18 30.22 42 93.71 85.38 155.55 33 38.64 26.09 35.19 43 105.11 99.02 186.54 34 42.16 29.44 41.06 44 118.37 115.31 224.64 35 46.12 33.30 48.03 45 133.88 134.88 271.76 Pa 36 50.59 37.75 56.31 46 152.10 158.51 330.35 H 37 55.63 42.92 66.19 47 173.64 187.21 403.67 38 61.35 48.93 78.03 48 199.26 222.31 496.01 39 67.87 55.96 92.25 49 229.93 265.51 613.16 H/3 40 75.31 64.20 109.41 50 266.89 319.07 762.89 41 83.86 73.90 130.22 0.25 H 0.25 H * HD D 0.75 H Inclination factors by Meyerhof (1963) (a) σ = 0.65yHK (b) the larger of σ₁ =yH 7. =yH[1–4 €/] 4c a BN. Fed =1+0.4(+) D B B° F F (1- L N Fas=1+() tan o' F =1-0.4(+) +(은) B Fad 1+2 tan o'(1-sin ')2 F= (1-5 B F =1 0.5 H 0.25 H and σ = 0.37H (c) σ = 0.27H to 0.4yH K = cosa cosa cos α-cos² cosa + √cos² α-cos² 'Q' Q' H (a) Wall movement away from soil C₁₂ Pa B-8 c'=0 w R sin² (B+) (b) K sin ẞsin(-8) 1+, sin(+6) sin(-a) sin(B-) sin(a + ẞ)

[3] The excavation of a construction project of a commercial building is shown in Figure 3. The following figure shows the excavation profile, with the bottom 12 m below the ground surface. The width and length of the excavation are 20 m and 30 m, respectively. The piezometer shows that the head in the gravel layer below the bottom of the cut is 7 m below the ground surface. The unit weight of water is yw = 9.8 kN/m³. Answer the following questions. 2 m 3.5 m 3.5 m 3 m A 12 m Soft clay 7 m B Ysat 18 kN/m³ Undrained shear strength C = 50 kPa 8 m Table 4.2 Bearing Capacity Factors $' No Na Ny $' N N₁₂ Ny 0 5.14 1.00 0.00 1 5.38 1.09 0.07 2 5.63 1.20 0.15 3 5.90 1.31 0.24 4 6.19 1.43 0.34 5 6.49 1.57 0.45 21 6 6.81 1.72 0.57 7 7.16 1.88 0.71 8 7.53 2.06 0.86 9 7.92 2.25 1.03 10 8.35 2.47 1.22 11 8.80 2.71 1.44 12 9.28 2.97 1.69 13 9.81 3.26 1.97 14 10.37 3.59 2.29 BERDA2222222223 16 11.63 4.34 3.06 17 12.34 4.77 3.53 18 13.10 5.26 4.07 FS= 19 13.93 5.80 4.68 20 14.83 6.40 5.39 15.82 7.07 6.20 16.88 7.82 7.13 18.05 8.66 8.20 Yay= 24 19.32 9.60 9.44 H 25 20.72 10.66 10.88 26 22.25 11.85 12.54 (A)(s²) BT if T≤B√2, B'=B/√2 if T>B/√2, B" = √2B' B" L CN. (1+0.227) (y+2) H H [4 [₁H₁ +₂H₂+...+y„H„] (C₁ +C₂)(s²) Cav= [c,H₁+c₂H₂++cH»] M M = max max 27 23.94 13.20 14.47 8 28 25.80 14.72 16.72 29 27.86 16.44 19.34 K≈ 1-sin o' 30 30.14 18.40 22.40 15 10.98 3.94 2.65 31 32.67 20.63 25.99 (continued) Table 4.2 Bearing Capacity Factors (Continued) 8 K≈0.95-sin Ko(overconsoklate) K OCR o(normally consolidated) Rankine's active earth pressure Coulomb's active earth pressure Paimax Active force Gravel (Hard Layer) Figure 3 (3.1) List briefly describe ALL of the possible failure modes of a deep excavation during construction. (3.2) Compute the strut loads in the supports. Assuming horizontal spacing between the supports is 4 m. Hint: Use the apparent earth pressure envelope developed by Peck (1969) to estimate the lateral earth pressure. (3.3) Compute the factor of safety against the bottom heave. (3.4) What type(s) of wall would you suggest for this site? Choose the appropriate one(s) and give your reasons. (a) H pile and wood lagging. (b) Steel sheet pile. (c) Diaphragm wall. (d) Continuous bored pile. Equations and Tables: qi Bearing capacity equation: q=c'N FFF+q'N FFF +0.5BN FFF Shape factors by De Beer Depth factors by Hansen (1970) (1970) F₁ =1+()) and Hanna and Meyerhof (1981) $' No Na Ny $' No N₁ Ny 32 35.49 23.18 30.22 42 93.71 85.38 155.55 33 38.64 26.09 35.19 43 105.11 99.02 186.54 34 42.16 29.44 41.06 44 118.37 115.31 224.64 35 46.12 33.30 48.03 45 133.88 134.88 271.76 Pa 36 50.59 37.75 56.31 46 152.10 158.51 330.35 H 37 55.63 42.92 66.19 47 173.64 187.21 403.67 38 61.35 48.93 78.03 48 199.26 222.31 496.01 39 67.87 55.96 92.25 49 229.93 265.51 613.16 H/3 40 75.31 64.20 109.41 50 266.89 319.07 762.89 41 83.86 73.90 130.22 0.25 H 0.25 H * HD D 0.75 H Inclination factors by Meyerhof (1963) (a) σ = 0.65yHK (b) the larger of σ₁ =yH 7. =yH[1–4 €/] 4c a BN. Fed =1+0.4(+) D B B° F F (1- L N Fas=1+() tan o' F =1-0.4(+) +(은) B Fad 1+2 tan o'(1-sin ')2 F= (1-5 B F =1 0.5 H 0.25 H and σ = 0.37H (c) σ = 0.27H to 0.4yH K = cosa cosa cos α-cos² cosa + √cos² α-cos² 'Q' Q' H (a) Wall movement away from soil C₁₂ Pa B-8 c'=0 w R sin² (B+) (b) K sin ẞsin(-8) 1+, sin(+6) sin(-a) sin(B-) sin(a + ẞ)

Principles of Foundation Engineering (MindTap Course List)

8th Edition

ISBN:9781305081550

Author:Braja M. Das

Publisher:Braja M. Das

Chapter10: Drilled-shaft Foundations

Section: Chapter Questions

Problem 10.9P

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Transcribed Image Text:[3] The excavation of a construction project of a commercial building is shown in Figure 3. The following figure shows the excavation profile, with the bottom 12 m below the ground surface. The width and length of the excavation are 20 m and 30 m, respectively. The piezometer shows that the head in the gravel layer below the bottom of the cut is 7 m below the ground surface. The unit weight of water is yw = 9.8 kN/m³. Answer the following questions. 2 m 3.5 m 3.5 m 3 m A 12 m Soft clay 7 m B Ysat 18 kN/m³ Undrained shear strength C = 50 kPa 8 m Table 4.2 Bearing Capacity Factors $' No Na Ny $' N N₁₂ Ny 0 5.14 1.00 0.00 1 5.38 1.09 0.07 2 5.63 1.20 0.15 3 5.90 1.31 0.24 4 6.19 1.43 0.34 5 6.49 1.57 0.45 21 6 6.81 1.72 0.57 7 7.16 1.88 0.71 8 7.53 2.06 0.86 9 7.92 2.25 1.03 10 8.35 2.47 1.22 11 8.80 2.71 1.44 12 9.28 2.97 1.69 13 9.81 3.26 1.97 14 10.37 3.59 2.29 BERDA2222222223 16 11.63 4.34 3.06 17 12.34 4.77 3.53 18 13.10 5.26 4.07 FS= 19 13.93 5.80 4.68 20 14.83 6.40 5.39 15.82 7.07 6.20 16.88 7.82 7.13 18.05 8.66 8.20 Yay= 24 19.32 9.60 9.44 H 25 20.72 10.66 10.88 26 22.25 11.85 12.54 (A)(s²) BT if T≤B√2, B'=B/√2 if T>B/√2, B" = √2B' B" L CN. (1+0.227) (y+2) H H [4 [₁H₁ +₂H₂+...+y„H„] (C₁ +C₂)(s²) Cav= [c,H₁+c₂H₂++cH»] M M = max max 27 23.94 13.20 14.47 8 28 25.80 14.72 16.72 29 27.86 16.44 19.34 K≈ 1-sin o' 30 30.14 18.40 22.40 15 10.98 3.94 2.65 31 32.67 20.63 25.99 (continued) Table 4.2 Bearing Capacity Factors (Continued) 8 K≈0.95-sin Ko(overconsoklate) K OCR o(normally consolidated) Rankine's active earth pressure Coulomb's active earth pressure Paimax Active force Gravel (Hard Layer) Figure 3 (3.1) List briefly describe ALL of the possible failure modes of a deep excavation during construction. (3.2) Compute the strut loads in the supports. Assuming horizontal spacing between the supports is 4 m. Hint: Use the apparent earth pressure envelope developed by Peck (1969) to estimate the lateral earth pressure. (3.3) Compute the factor of safety against the bottom heave. (3.4) What type(s) of wall would you suggest for this site? Choose the appropriate one(s) and give your reasons. (a) H pile and wood lagging. (b) Steel sheet pile. (c) Diaphragm wall. (d) Continuous bored pile. Equations and Tables: qi Bearing capacity equation: q=c'N FFF+q'N FFF +0.5BN FFF Shape factors by De Beer Depth factors by Hansen (1970) (1970) F₁ =1+()) and Hanna and Meyerhof (1981) $' No Na Ny $' No N₁ Ny 32 35.49 23.18 30.22 42 93.71 85.38 155.55 33 38.64 26.09 35.19 43 105.11 99.02 186.54 34 42.16 29.44 41.06 44 118.37 115.31 224.64 35 46.12 33.30 48.03 45 133.88 134.88 271.76 Pa 36 50.59 37.75 56.31 46 152.10 158.51 330.35 H 37 55.63 42.92 66.19 47 173.64 187.21 403.67 38 61.35 48.93 78.03 48 199.26 222.31 496.01 39 67.87 55.96 92.25 49 229.93 265.51 613.16 H/3 40 75.31 64.20 109.41 50 266.89 319.07 762.89 41 83.86 73.90 130.22 0.25 H 0.25 H * HD D 0.75 H Inclination factors by Meyerhof (1963) (a) σ = 0.65yHK (b) the larger of σ₁ =yH 7. =yH[1–4 €/] 4c a BN. Fed =1+0.4(+) D B B° F F (1- L N Fas=1+() tan o' F =1-0.4(+) +(은) B Fad 1+2 tan o'(1-sin ')2 F= (1-5 B F =1 0.5 H 0.25 H and σ = 0.37H (c) σ = 0.27H to 0.4yH K = cosa cosa cos α-cos² cosa + √cos² α-cos² 'Q' Q' H (a) Wall movement away from soil C₁₂ Pa B-8 c'=0 w R sin² (B+) (b) K sin ẞsin(-8) 1+, sin(+6) sin(-a) sin(B-) sin(a + ẞ)

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