基于砂土刚度衰减模型的修正p-y曲线法

Modified p-y Curves Method Based on Degradation Stiffness Model of Sand

现有的p-y曲线大多是基于小直径桩在有限循环次数下的加载试验得到,难以精确描述大直径桩基在长期水平循环荷载下的位移累积以及土体的循环弱化特性.基于此,首先对Abaqus进行二次开发,建立了能考虑砂土长期循环弱化效应的桩土系统刚度衰减模型,并在数值分析的基础上得到了长期循环荷载下大直径桩的p-y曲线.然后通过引入循环反力比的概念,获取了桩土系统的刚度衰减参数,同时实现了对初始地基反力模量的修正,进而提出了基于砂土刚度衰减模型的修正p-y曲线法.最后,通过与试验结果进行对比分析,验证了该方法的有效性.该修正p-y曲线法能够综合考虑荷载特性、循环次数、砂土刚度循环弱化等因素,可为长期水平循环作用下大直径桩基础的初步设计提供一种简明有效的分析方法.

Most of the existing p-y curves are based on the model test results of small-diameter pile under cyclic loading of finite times,which makes it difficult to accurately describe the displacement accumulation of large-diameter pile under long-term horizontal cyclic loading and the cyclic weakening characteristics of soil.Therefore,based on the subroutine provided by Abaqus,a stiffness degradation model of the pile-soil system considering the long-term cyclic weakening effect of sand was established,and the p-y curves of large-diameter pile were obtained based on numerical analysis.Then,by introducing the concept of cyclic reaction ratio,the stiffness degradation factor of the pile-soil system was obtained,and the initial foundation reaction modulus was modified as well.Finally,a modified p-y curves method based on the degradation stiffness model of sand was proposed.By comparing with the test results,the validity of this method is verified.This modified p-y curves method,which is able to consider the effects of loading characteristics,number of cycles,cyclic weakening of sand stiffness,provides a concise and effective analysis method for the preliminary design of monopile foundation under long-term horizontal cyclic loading.