THE IMPROVEMENT OF PILE PERFORMANCE BY BASE GROUTING.

Post-grouting pile bases with cement grout is a common practice when they are designed to carry a significant end-bearing load. There are many records of load tests on piles treated in this way which indicate reduced settlements under load. The improvement in pile performance is often attributed to increased base stiffness, and sometimes it is suggested that the ultimate capacity of the ground has benefitted. This paper deals with the mechanics of improved pile performance and shows that, while there may be several lesser effects in given cases, the paramount cause of enhanced performance is the reversal of shaft friction during the grout injection process. (A)