Performance of High Capacity Socketed H-Piles with Long Rock Socket

Synopsis

The pile capacity is commonly calculated by the engineers as the lesser of its structural capacity and the ultimate resistance of ground supporting it using a generalized equation irrespective of the shaft type, socket diameter, socket length, rock type and grout strength. This equation may be over-simplified and risky if the pile/grout/rock interaction is not considered. Based on the loading tests of 6 instrumented socketed piles with 4m – 6m rock socket by others and 35 non-instrumented socketed H-piles with 5m – 34m rock socket by the author, the load-transfer mechanism in long rock socket is found dependent not only on the mobilization of shear resistance in soil and rock layers, but also largely on the steel/grout bond behavior. A side resistance distribution factor αs is introduced as a simple and practical index to represent the load-transfer mechanism along the pile shaft and to the socket. It would increase with…