The section of a 4 × 4 group pile in a layered saturated clay is shown in Figure 1. The piles are square in cross-section (356 mm × 356 mm). The center-to-center spacing (d) of the piles is 1 m. Determine the allowable loadbearing capacity of the pile group. Use FS = 3 and Table 1.

Figure 1

Table 1

               

	α
≤ 0.1	1.00
0.2	0.92
0.3	0.82
0.4	0.74
0.6	0.62
0.8	0.54
1.0	0.48
1.2	0.42
1.4	0.40
1.6	0.38
1.8	0.36
2.0	0.35
2.4	0.34
2.8	0.34

5 m 6 m 6m Clay C= 25 kN/m Clay C = 45 kN/m Clay c=60 kN/m C