1. In what kind of geological conditions and for what types of building would mat foundations be preferred over other forms of foundation? What are the key advantages of mat foundation under these conditions? If the groundwater table at a site located above the slab of the mat foundation and would rise considerably in wet seasons, indicate that whether it may cause any problem to the building and the means to overcome them. Why we usually use undrained shear strength instead of effective cohesion and effective friction angle to determine the factor of safety for bearing capacity when designing mat foundation? Figure, Tables, and Equations: qu = 5.14c (1+0.1952)(1 +0.4%)+ +q B (10.11) Pile: Meyerhof's method = Q = 4,9, Aq'N ≤ Aq P 9₁ = 0.5ptan o' TABLE 12.6 Interpolated Values of No Based on Meyerhof's Theory Soil friction angle, ' (deg) N₁₂ qu(net) qu-q= 5.14c 1 + 0.195: 5.14c.(1+ 52) (1+0.4%) (10.12) qu(net) = all(net) FS 1.713c. (1 + 0.1952) (1+0.4%) (10.13) General bearing capacity equation : qu = c'NcFcs FcaFci+q'NqFqsFqaFqi + 0.5yBNyFysFyaFyi Shape factors by De Beer Depth factors by Hansen (1970) (1970) Inclination factors by Meyerhof 31 (1963) and Hanna and Meyerhof (1981) 33 Fes 1+) BN LNC Fcd 1+0.4( ẞ° Fci = Fqi = (1 900)2 35 B Fas 1+) tan o' Fqd = 1 + 2 tan q' (1 − sin 4')² Dr - Fyi = (1 2 37 - B 38 Fys = = 1-0.4(7) Fyd = 1 22222222222223226229 20 21 12.4 13.8 15.5 17.9 24 21.4 25 26.0 29.5 27 34.0 28 39.7 46.5 30 56.7 68.2 81.0 96.0 34 115.0 143.0 168.0 194.0 231.0 276.0 40 346.0 41 420.0 42 525.0 Shallow foundation: TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) 43 650.0 TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) (Continued) 44 780.0 45 930.0 $' N₂ N₁ Ny $' Ne No No 22 16.88 7.82 7.13 37 55.63 42.92 66.19 $' No N₁ Ny $' No N₁ Ny 0 5.14 1.00 0.00 11 8.80 2.71 1.44 1 5.38 1.09 0.07 12 9.28 2.97 1.69 2 5.63 1.20 0.15 13 9.81 3.26 1.97 3 5.90 1.31 0.24 14 10.37 3.59 2.29 23282 18.05 8.66 8.20 38 61.35 48.93 78.03 24 19.32 9.60 9.44 39 67.87 55.96 92.25 25 20.72 10.66 10.88 40 75.31 64.20 109.41 26 22.25 11.85 12.54 41 83.86 73.90 130.22 27 23.94 13.20 14.47 42 93.71 85.38 155.55 4 6.19 1.43 0.34 15 10.98 3.94 2.65 28 25.80 14.72 16.72 43 105.11 99.02 186.54 5 6.49 1.57 0.45 16 11.63 29 27.86 16.44 4.34 19.34 44 118.37 115.31 224.64 3.06 30 30.14 18.40 22.40 45 133.88 134.88 271.76 6 6.81 1.72 0.57 17 12.34 4.77 3.53 31 32.67 20.63 25.99 46 152.10 158.51 330.35 7 7.16 1.88 0.71 18 13.10 5.26 4.07 32 35.49 23.18 30.22 47 173.64 187.21 403.67 8 7.53 2.06 0.86 19 13.93 5.80 4.68 33 38.64 26.09 35.19 48 199.26 222.31 496.01 9 7.92 2.25 1.03 20 14.83 6.40 5.39 34 42.16 29.44 41.06 49 229.93 265.51 613.16 10 8.35 2.47 1.22 21 15.82 7.07 6.20 35 46.12 33.30 48.03 50 266.89 319.07 762.89 (continued) 36 50.59 37.75 56.31 The critical depth for skin friction in piles L'≈15D The unit frictional resistance or the unit skin friction f = Kσ tan S'

1. In what kind of geological conditions and for what types of building would mat foundations be preferred over other forms of foundation? What are the key advantages of mat foundation under these conditions? If the groundwater table at a site located above the slab of the mat foundation and would rise considerably in wet seasons, indicate that whether it may cause any problem to the building and the means to overcome them. Why we usually use undrained shear strength instead of effective cohesion and effective friction angle to determine the factor of safety for bearing capacity when designing mat foundation? Figure, Tables, and Equations: qu = 5.14c (1+0.1952)(1 +0.4%)+ +q B (10.11) Pile: Meyerhof's method = Q = 4,9, Aq'N ≤ Aq P 9₁ = 0.5ptan o' TABLE 12.6 Interpolated Values of No Based on Meyerhof's Theory Soil friction angle, ' (deg) N₁₂ qu(net) qu-q= 5.14c 1 + 0.195: 5.14c.(1+ 52) (1+0.4%) (10.12) qu(net) = all(net) FS 1.713c. (1 + 0.1952) (1+0.4%) (10.13) General bearing capacity equation : qu = c'NcFcs FcaFci+q'NqFqsFqaFqi + 0.5yBNyFysFyaFyi Shape factors by De Beer Depth factors by Hansen (1970) (1970) Inclination factors by Meyerhof 31 (1963) and Hanna and Meyerhof (1981) 33 Fes 1+) BN LNC Fcd 1+0.4( ẞ° Fci = Fqi = (1 900)2 35 B Fas 1+) tan o' Fqd = 1 + 2 tan q' (1 − sin 4')² Dr - Fyi = (1 2 37 - B 38 Fys = = 1-0.4(7) Fyd = 1 22222222222223226229 20 21 12.4 13.8 15.5 17.9 24 21.4 25 26.0 29.5 27 34.0 28 39.7 46.5 30 56.7 68.2 81.0 96.0 34 115.0 143.0 168.0 194.0 231.0 276.0 40 346.0 41 420.0 42 525.0 Shallow foundation: TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) 43 650.0 TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) (Continued) 44 780.0 45 930.0 $' N₂ N₁ Ny $' Ne No No 22 16.88 7.82 7.13 37 55.63 42.92 66.19 $' No N₁ Ny $' No N₁ Ny 0 5.14 1.00 0.00 11 8.80 2.71 1.44 1 5.38 1.09 0.07 12 9.28 2.97 1.69 2 5.63 1.20 0.15 13 9.81 3.26 1.97 3 5.90 1.31 0.24 14 10.37 3.59 2.29 23282 18.05 8.66 8.20 38 61.35 48.93 78.03 24 19.32 9.60 9.44 39 67.87 55.96 92.25 25 20.72 10.66 10.88 40 75.31 64.20 109.41 26 22.25 11.85 12.54 41 83.86 73.90 130.22 27 23.94 13.20 14.47 42 93.71 85.38 155.55 4 6.19 1.43 0.34 15 10.98 3.94 2.65 28 25.80 14.72 16.72 43 105.11 99.02 186.54 5 6.49 1.57 0.45 16 11.63 29 27.86 16.44 4.34 19.34 44 118.37 115.31 224.64 3.06 30 30.14 18.40 22.40 45 133.88 134.88 271.76 6 6.81 1.72 0.57 17 12.34 4.77 3.53 31 32.67 20.63 25.99 46 152.10 158.51 330.35 7 7.16 1.88 0.71 18 13.10 5.26 4.07 32 35.49 23.18 30.22 47 173.64 187.21 403.67 8 7.53 2.06 0.86 19 13.93 5.80 4.68 33 38.64 26.09 35.19 48 199.26 222.31 496.01 9 7.92 2.25 1.03 20 14.83 6.40 5.39 34 42.16 29.44 41.06 49 229.93 265.51 613.16 10 8.35 2.47 1.22 21 15.82 7.07 6.20 35 46.12 33.30 48.03 50 266.89 319.07 762.89 (continued) 36 50.59 37.75 56.31 The critical depth for skin friction in piles L'≈15D The unit frictional resistance or the unit skin friction f = Kσ tan S'

Principles of Foundation Engineering (MindTap Course List)

8th Edition

ISBN:9781305081550

Author:Braja M. Das

Publisher:Braja M. Das

Chapter8: Mat Foundations

Section: Chapter Questions

Problem 8.4P

See similar textbooks