ABSTRACT
Case 3: When Layer 1 is Dense Sand and Layer 2 is Loose Sand (c, = c2 = 0) Proceeding in the same way as explained earlier the expression for qu for a rectangular footing may be expressed as
(12.60)
(12.61)
(12.62)
Case 4: Layer 1 is Stiff Saturated Clay (tP, = 0) and Layer 2 is Saturated Soft Clay (tP2 = 0) The ultimate bearing capacity of the layered system can be given as
J.£. = 5.14 c2 =.:1. ql 5.14c1 c1
(12.63)
(12.64)
(12.65)
Example 12.17 A rectangular footing of size 3 x 2 m is founded at a depth of 1.5 m in a clay stratum of very stiff consistency. A clay layer of medium consistency is located at a depth of 1.5 m (= H) below the bottom of the footing (Fig. Ex. 12.17). The soil parameters of the two clay layers are as follows:
Top clay layer: c1 = 175 kN/m2
Figure Ex. 12.17
Y1 = 17.5 kN/m3
Bottom layer: c2 = 40 kN/m 2
Y2 = 17.0 kN/m3
Estimate the ultimate bearing capacity and the allowable bearing pressure on the footing with a factor of safety of 3.
