To support a heavy column loading, a nine-pile group consisting of steel pipe piles 0.35 m in diameter is installed in a loose sand where the unit weight is 16.5 kN/m 3 and the angle of internal...

To support a heavy column loading, a nine-pile group consisting of steel pipe piles 0.35 m in diameter is installed in a loose sand where the unit weight is 16.5 kN/m³
and the angle of internal friction is 33°. The piles are embedded 15 m and the pile spacing is 3 diameters. Use the β-method procedure for an effective stress analysis to determine the group capacity for the nine piles, assuming that the sand between the piles is densified by the driving operation to the extent that the piles and the interlocked soil act as a unit. Use a factor of safety of 2.75. Then, compare this group capacity with the capacity based upon a single pile load (refer to Problem 39) times the number of piles.