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: 7.5.14c.(1+0.1951+0.4%)+4 = B (10.11) B = Qu(net) quq = 5.14c 1 + 0.195- q-5.14, (1+0.1951+04) (10.12) all(net) Qu(net) FS 3c,(1 = 1.713c 10.195 1952) (1 D 1+0.4- (10.13) B ← For FS=3 General bearing capacity equation: qu = c'NcFcs Fca Fci+q'NqFqsFqaFqi + 0.5yBNy Fys Fya Fyi Shape factors by De Beer (1970) B N = Fes 1+()( LNC Depth factors by Hansen (1970) Fed = 1 + 0.4 (4) Inclination factors by Meyerhof (1963) and Hanna and Meyerhof (1981) Fci = Fqi = (1- 90°)² Fqs = 1 + (→) t B tan o' = Fad 1+2 tan o' (1 − sin o') 2. Df - B Fyi = (1-2)² Fy, = 1-0.4(+) B Fyd = = 1 Bearing capacity factors Ne, Na, Ny TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) (Continued) No Na Ny $' No Na Ny 22 16.88 7.82 7.13 37 55.63 42.92 66.19 TABLE 6.2 Bearing Capacity Factors From Eqs. (6.30), (6.29), and (6.31) 23 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 $' Ne N₁ Ny $' No Na Ny 25 20.72 10.66 10.88 40 75.31 64.20 109.41 0 5.14 1.00 0.00 11 8.80 2.71 1.44 26 22.25 11.85 12.54 41 83.86 73.90 130.22 1 5.38 1.09 0.07 12 9.28 2.97 1.69 27 23.94 13.20 14.47 42 93.71 85.38 2 5.63 1.20 155.55 0.15 13 9.81 3.26 1.97 28 25.80 14.72 16.72 43 105.11 99.02 186.54 3 5.90 1.31 0.24 14 10.37 3.59 2.29 29 27.86 16.44 19.34 44 118.37 115.31 224.64 4 6.19 1.43 0.34 15 10.98 3.94 2.65 30 30.14 18.40 22.40 45 133.88 134.88 271.76 5 6.49 1.57 0.45 16 11.63 4.34 3.06 31 32.67 20.63 25.99 46 152.10 158.51 330.35 6 6.81 1.72 0.57 17 12.34 4.77 3.53 7 7.16 1.88 0.71 18 13.10 5.26 4.07 333 35.49 23.18 30.22 47 173.64 187.21 403.67 38.64 26.09 35.19 48 199.26 222.31 496.01 8 7.53 2.06 0.86 19 13.93 5.80 4.68 34 42.16 29.44 41.06 49 229.93 265.51 9 7.92 2.25 1.03 20 14.83 613.16 6.40 5.39 35 46.12 33.30 48.03 50 266.89 319.07 762.89 10 8.35 2.47 1.22 21 15.82 7.07 6.20 36 50.59 37.75 56.31 (continued)