Long Term Settlement of Piles under Repetitive Loading from Trains

This paper describes how the design of piles is an essentially empirical process that is derived by back-analysis of full-scale static load tests. The results of the tests are then related to soil properties, and the design proceeds and pile geometries are selected so that the settlements of the piles under design loads are acceptably far from failure. Designers are most comfortable when the majority of the design load is static. This paper describes dynamic load tests on piles and the consequences on design of a piled slab for the Channel Tunnel Rail Link where the dynamic loading from trains was significantly larger than the static or “dead” load. Ground and pile conditions are related to train loading situations where large permanent settlements could occur. Design methods are described that enable long term settlements of piles to be predicted over the structure’s design life.