Meso-scale Analysis Of Mechanical And Deformation Behaviour Of Rigid Pile Composite Foundation

Rigid Pile Composite Foundation (RPCF) is used extensively in engineering practice,however, at present the theoretical study about it falls far behind its practical application.Therefore, in-deep study on the mechanical and deformation behaviour of RPCF has greattheoretical and practical significance.This thesis establishes a meso model of single pile static load test of RPCF withDiscrete Element Method (DEM), based on which analyses on the mechanical anddeformation behaviour (the variation of pile soil stress ratio, distribution of negativefriction along pile shaft, distribution of stress and displacement in cushion and soil betweenpiles) of RPCF under different loads are conducted; after that, case studies, focusing on theinfluence of friction coefficient, contact stiffness, contact stiffness ratio and thickness ofsand cushion on the mechanical and deformation behaviour of RPCF, are taken. The resultsshow that DEM is more applicable than continuum methods to the simulation of RPCF;horizontal stress of sand cushion is much higher than that of soil between piles; thesettlement of particles above pile head is significantly less than its counterparts of particlesin other zones; the horizontal displacement mainly occurs in the triangle zone under thefooting.In light of the expensive cost of calculation for RPCF solely by DEM, this thesisestablishes a meso-micro double scale model of single pile static load test of RPCF withDiscrete Element Method (DEM) and Finite Difference Method (FDM), then compares thecalculation results in coupling and DEM model. The results show that DEM-FDM doublescale analysis can reflect the discontinuum bahaviour of sand cushion, rotation of particlesand penetration of rigid pile into sand cushion, thus is applicable to the simulation of RPCF;DEM-FDM double scale analysis saves around two thirds of calculation time than DEMsingle scale analysis, hence can be used in large scale simulation of RPCF.