An Experimental Study of Foundation Underpinning by Piles

Existing buildings sometimes experience excessive settlement under their design loads or face the prospect of excessive settlement in the future if a change of building use is required and increased foundation loadings will occur. Several methods of foundation enhancement are available to arrest settlements or improve the future performance of existing foundations including the method of underpinning by piles. To investigate further the behavior of underpinning piles, which are installed beneath a settling foundation, two series of controlled model underpinning tests have been carried out in normally consolidated clay with different loading levels and different pile lengths. In this paper, the test procedure is described, and results of the two different test series are presented. Some comparisons are also made between the observed behavior and predicted from numerical finite element analyses and these are discussed briefly.