Soil disturbance from pile driving in sensitive clay

Soil disturbance due to the driving of two groups of 116 concrete piles each in sensitive marine clay was studied on a construction project in eastern Canada. Pore-water pressures, heave, and lateral movement of soil and piles, and tests of strength, compressibility, and consistency limits of the soil were observed prior to and up to 3 months after pile driving whereas observations of pore-water pressures were continued for an additional 5 months. Driving of the piles had little effect on the compressibility and consistency limits of the marine clay, but the in situ shear strength and cone penetration resistance were reduced by about 15 and 30%, respectively. Soil heave within the group of piles decreased linearly with depth from a maximum of 450 mm (18 in.) at the ground surface to about zero at the pile tips, and in volume amounted to approximately 55% of the soil displaced by the piles. The vertical heave outside the pile group was confined to a horizontal distance of 12 m (39 pile diameters). During p...