A 20 m long concrete pile with a rectangular cross-section of 460 mm × 460 mm fully embedded in the sand is shown in Figure P 12.2. Estimate the ultimate point load or tip resistance Qp by the following 4 methods and discuss. Necessary variables and formulae: Ap q' Pa Area of the pile tip Effective vertical stress at the level of the pile tip Atmospheric pressure 100 kN/m² Mean effective normal ground stress at the level of the pile point Irr Reduced rigidity index for the soil Ir Rigidity index for the soil Δ Average volumetric strain in the plastic zone below the pile point Ms Poisson's ratio of soil exp[(')tan '] 1) Terzaghi's method (Use Nq = 1-sin o' 2) Meyerhof's method (Use Table 12.6 for interpolation of N₁) Sand: Q = min(q', 0.5patano') N₁Ap 3) Vesic's method (Use Table 12.8 for interpolation of N and modulus of elasticity of soil of Es = 600pa) Sand: Qp='NAp = 3 where σ'o 1+2Ko q', Ko = 1 − sinø', Irr Ir = ' Ir = 1+1+A Es 2(1+)q'tand' TABLE 12.6 Interpolated Values of N₁₂ Based on Meyerhof's Theory 10 20 Bearing capacity factor, N* 9 40 60 80 100 200 For 25° ≤ ¢' ≤ 45°, µs = 0.1 +0.3 (0-25°), A = 0.005 (1-0-25°) 9 4) Coyle and Castello's method (Use Figure 12.20 for extrapolation of N₁₁) Sand: Qp=q'N Ap 0- Soil friction angle, &' (deg) N₁₁ 20 12.4 10 21 13.8 22 15.5 23 17.9 20 Concrete pile 460 mm X 460 mm 24 21.4 25 26.0 26 29.5 Loose sand 27 34.0 $1₁ = 30° 20 m y = 18.6 kN/m³ 28 39.7 29 46.5 Embedment ratio, L/D 40 30 56.7 50 T 31 68.2 32 81.0 60 60 T 32° 36° 6' = 30° 40° 38° 34° 33 96.0 34 115.0 70 35 143.0 Dense sand 36 168.0 Φ'2 = 420 y=18.5 kN/m³ 37 194.0 FIGURE 12.20 Variation of N with L/D (Based on Coyle and Castello, 1981) 38 231.0 39 276.0 FIGURE P 12.2 40 346.0 41 420.0 42 525.0 43 650.0 44 780.0 45 930.0 TABLE 12.8 Bearing Capacity Factors No Based on the Theory of Expansion of Cavities Irr $' 10 20 40 60 80 100 200 300 400 500 29 222222231335 12.12 15.95 20.98 24.64 27.61 30.16 39.70 46.61 52.24 57.06 26 13.18 17.47 23.15 27.30 30.69 33.60 44.53 52.51 59.02 64.62 27 14.33 19.12 25.52 30.21 34.06 37.37 49.88 59.05 66.56 73.04 28 15.57 20.91 28.10 33.40 37.75 41.51 55.77 66.29 74.93 82.40 16.90 22.85 30.90 36.87 41.79 46.05 62.27 74.30 84.21 92.80 30 18.24 24.95 33.95 40.66 46.21 51.02 69.43 83.14 94.48 104.33 19.88 27.22 37.27 44.79 51.03 56.46 77.31 92.90 105.84 117.11 21.55 29.68 40.88 49.30 56.30 62.41 85.96 103.66 118.39 131.24 23.34 32.34 44.80 54.20 62.05 68.92 95.46 115.51 132.24 146.87 34 25.28 35.21 49.05 59.54 68.33 76.02 105.90 128.55 147.51 164.12 27.36 38.32 53.67 65.36 75.17 83.78 117.33 142.89 164.33 183.16 36 29.60 41.68 58.68 71.69 82.62 92.24 129.87 158.65 182.85 204.14 37 32.02 45.31 64.13 78.57 90.75 101.48 143.61 175.95 203.23 227.26 38 34.63 49.24 70.03 86.05 99.60 111.56 158.65 194.94 225.62 252.71 39 37.44 53.50 76.45 94.20 109.24 122.54 175.11 215.78 250.23 280.71 40 40.47 58.10 83.40 103.05 119.74 134.52 193.13 238.62 277.26 311.50 41 43.74 63.07 90.96 112.68 131.18 147.59 212.84 263.67 306.94 345.34 42 47.27 68.46 99.16 123.16 143.64 161.83 234.40 291.13 339.52 382.53 43 51.08 74.30 108.08 134.56 157.21 177.36 257.99 321.22 375.28 423.39 44 55.20 80.62 117.76 146.97 172.00 194.31 283.80 354.20 414.51 468.28 45 59.66 87.48 128.28 160.48 188.12 212.79 312.03 390.35 457.57 517.58 Based on data from "Design of Pile Foundations," by A. S. Vesic. Synthesis of Highway Practice by American Association of State Highway and Transportation, 1977

A 20 m long concrete pile with a rectangular cross-section of 460 mm × 460 mm fully embedded in the sand is shown in Figure P 12.2. Estimate the ultimate point load or tip resistance Qp by the following 4 methods and discuss. Necessary variables and formulae: Ap q' Pa Area of the pile tip Effective vertical stress at the level of the pile tip Atmospheric pressure 100 kN/m² Mean effective normal ground stress at the level of the pile point Irr Reduced rigidity index for the soil Ir Rigidity index for the soil Δ Average volumetric strain in the plastic zone below the pile point Ms Poisson's ratio of soil exp[(')tan '] 1) Terzaghi's method (Use Nq = 1-sin o' 2) Meyerhof's method (Use Table 12.6 for interpolation of N₁) Sand: Q = min(q', 0.5patano') N₁Ap 3) Vesic's method (Use Table 12.8 for interpolation of N and modulus of elasticity of soil of Es = 600pa) Sand: Qp='NAp = 3 where σ'o 1+2Ko q', Ko = 1 − sinø', Irr Ir = ' Ir = 1+1+A Es 2(1+)q'tand' TABLE 12.6 Interpolated Values of N₁₂ Based on Meyerhof's Theory 10 20 Bearing capacity factor, N* 9 40 60 80 100 200 For 25° ≤ ¢' ≤ 45°, µs = 0.1 +0.3 (0-25°), A = 0.005 (1-0-25°) 9 4) Coyle and Castello's method (Use Figure 12.20 for extrapolation of N₁₁) Sand: Qp=q'N Ap 0- Soil friction angle, &' (deg) N₁₁ 20 12.4 10 21 13.8 22 15.5 23 17.9 20 Concrete pile 460 mm X 460 mm 24 21.4 25 26.0 26 29.5 Loose sand 27 34.0 $1₁ = 30° 20 m y = 18.6 kN/m³ 28 39.7 29 46.5 Embedment ratio, L/D 40 30 56.7 50 T 31 68.2 32 81.0 60 60 T 32° 36° 6' = 30° 40° 38° 34° 33 96.0 34 115.0 70 35 143.0 Dense sand 36 168.0 Φ'2 = 420 y=18.5 kN/m³ 37 194.0 FIGURE 12.20 Variation of N with L/D (Based on Coyle and Castello, 1981) 38 231.0 39 276.0 FIGURE P 12.2 40 346.0 41 420.0 42 525.0 43 650.0 44 780.0 45 930.0 TABLE 12.8 Bearing Capacity Factors No Based on the Theory of Expansion of Cavities Irr $' 10 20 40 60 80 100 200 300 400 500 29 222222231335 12.12 15.95 20.98 24.64 27.61 30.16 39.70 46.61 52.24 57.06 26 13.18 17.47 23.15 27.30 30.69 33.60 44.53 52.51 59.02 64.62 27 14.33 19.12 25.52 30.21 34.06 37.37 49.88 59.05 66.56 73.04 28 15.57 20.91 28.10 33.40 37.75 41.51 55.77 66.29 74.93 82.40 16.90 22.85 30.90 36.87 41.79 46.05 62.27 74.30 84.21 92.80 30 18.24 24.95 33.95 40.66 46.21 51.02 69.43 83.14 94.48 104.33 19.88 27.22 37.27 44.79 51.03 56.46 77.31 92.90 105.84 117.11 21.55 29.68 40.88 49.30 56.30 62.41 85.96 103.66 118.39 131.24 23.34 32.34 44.80 54.20 62.05 68.92 95.46 115.51 132.24 146.87 34 25.28 35.21 49.05 59.54 68.33 76.02 105.90 128.55 147.51 164.12 27.36 38.32 53.67 65.36 75.17 83.78 117.33 142.89 164.33 183.16 36 29.60 41.68 58.68 71.69 82.62 92.24 129.87 158.65 182.85 204.14 37 32.02 45.31 64.13 78.57 90.75 101.48 143.61 175.95 203.23 227.26 38 34.63 49.24 70.03 86.05 99.60 111.56 158.65 194.94 225.62 252.71 39 37.44 53.50 76.45 94.20 109.24 122.54 175.11 215.78 250.23 280.71 40 40.47 58.10 83.40 103.05 119.74 134.52 193.13 238.62 277.26 311.50 41 43.74 63.07 90.96 112.68 131.18 147.59 212.84 263.67 306.94 345.34 42 47.27 68.46 99.16 123.16 143.64 161.83 234.40 291.13 339.52 382.53 43 51.08 74.30 108.08 134.56 157.21 177.36 257.99 321.22 375.28 423.39 44 55.20 80.62 117.76 146.97 172.00 194.31 283.80 354.20 414.51 468.28 45 59.66 87.48 128.28 160.48 188.12 212.79 312.03 390.35 457.57 517.58 Based on data from "Design of Pile Foundations," by A. S. Vesic. Synthesis of Highway Practice by American Association of State Highway and Transportation, 1977

Principles of Foundation Engineering (MindTap Course List)

8th Edition

ISBN:9781305081550

Author:Braja M. Das

Publisher:Braja M. Das

Chapter9: Pile Foundations

Section: Chapter Questions

Problem 9.30P

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