The 14-in.-diameter pipe piles installed as described in the preceding problem will be used for a four-pile group where the pile spacing is 3 diameters. Determine the group capacity for the four piles...

The 14-in.-diameter pipe piles installed as described in the preceding problem will be used for a four-pile group where the pile spacing is 3 diameters. Determine the group capacity for the four piles (use the effective stress β-method), assuming that the soil between the piles is densified by the driving operation to the extent that the piles and interlocked soil act as a unit. Then, compare this group capacity with the capacity based upon single pile capacity times the number of piles. For both values, apply a factor of safety of 2.75.