高应力下碎石桩复合地基强度参数DEM模拟研究

DEM Simulation Study of Strength Parameters of Stone Column Composite Foundations Under High Stress

碎石桩复合地基中,常用Priebe参数叠加法计算复合地基等效抗剪强度。现有研究多基于常规路堤低应力下展开,少见在高应力作用下该方法适用性研究。对此,依托卢旺达某粘土心墙堆石坝坝基处理工程,利用离散元数值方法(DEM),模拟碎石桩复合地基单桩室内试验,研究了不同面积置换率下碎石桩复合试样的应力应变特性、细观破坏机理及等效抗剪强度,并与广泛使用的参数叠加法进行了对比。研究结果表明,高应力时碎石桩复合地基应力应变特性区别于低应力状态,呈应变硬化趋势;复合试样强度在高应力状态下呈现明显非线性趋势;参数叠加法计算所得的抗剪强度参数对复合地基强度有所高估,建议在工程运用中进行折减。

In stone column composite foundations,the Priebe parameter composite method is commonly used to calculate the equivalent shear strength.Most of the existing studies are based on low stresses in conventional embankments,but few studies have been carried out on the applicability of this method under high stresses.This study focuses on the foundation treatment project for a clay core rock fill dam in Rwanda.The stress-strain behavior,micro-failure mechanism and equivalent shear strength of composite specimens with different area replacement ratio were investigated by simulating large-scale triaxle tests with discrete element numerical methods and compared with the widely used parametric composite method.The results show that the stress-strain characteristics of stone column composite foundations at high stresses differ from those at low stresses,and show a strain hardening trend.Composite specimens show a significant non-linear trend in strength at high stresses.The shear strength parameters calculated by the parameter composite method overestimate the strength of composite foundations,and it is recommended that they be discounted in engineering applications.