ABSTRACT
The values of F1 and F2 are given in Fig. 13.7a. The elastic settlement at any point N (Fig. 13.7b) is given by
. qn (1-J,l2) Se at pOInt N; [IflBl+If2B2+If3B3+If4B4l (13.20c)E
Table 13.3 Typical range of values for Poisson's ratio (Bowles, 1996) Type of soil
Clay, saturated Clay, unsaturated Sandy clay Silt Sand (dense) Coarse (void ratio 0.4 to 0.7) Fine grained (void ratio = 0.4 to 0.7) Rock
0.4-0.5 0.1-0.3 0.2-0.3 0.3-0.35 0.2-0.4 0.15 0.25 0.1-0.4
0.2 0.3 0.4 0.5 0.6 0.7 0.8
(13.21)
Figure 13.7 Settlement due to load on surface of elastic layer (a) F, and F2 versus HIS (b) Method of estimating settlement (After Steinbrenner, 1934)
To obtain the settlement at the center of the loaded area, the principle of superposition is followed. In such a case N in Fig. 13.7b will be at the center of the area when B} =B4 =L2 =B3 and B2 = L}. Then the settlement at the center is equal to four times the settlement at anyone corner. The curves in Fig. 13.7a are based on the assumption that the modulus of deformation is constant with depth.
