Abstract:

In light of the effect of cushion on the composite foundation，according to the single pile composite foundation load testing of 12 piles， influences of the cushion on the pile-soil stress ratio have been studied; the test result indicates that both the thickness and rigidity of the cushion have effect on the pile-soil stress ratio，either the excessively thinness or over thick load capacity can not function well. To verify the test data，the single pile composite foundation finite element model is established using ANSYS program; the influences of the cushion thickness and deformation modulus on the pile-soil stress ratio have been analysed. Analysis and experimental results show that the value analysis and test result are consistent. Comparing the finite element analysis and test result, the selection principle of the cushion has determined so as to provide the cushion design basis in the process of composite foundation design.

Key words: cement fly-ash gravel (CFG) pile, composite foundation, cushion, finite elements, pile-soil stress ratio