| Most of the earthquakes at home and abroad have shown that the liquefaction of saturated sand is the major disasters in the earthquakes,and the foundation settlement caused by large deformation of sand after liquefaction are the essential causes of the damages of structures on the settlement.Therefore,the research of failure theories of sand liquefaction is one of the fundamental issues in the modern soil mechanic.Nowadays,traditional methods have its limitations in the study of sand liquefaction.Some problems of the liquefaction can not be explained on macroscopic scale,and traditional continuum mechanics is not applicable to study mechanical properties of sand,a discrete material.In order to discover the essential reason of sand liquefaction,researchers should carry out the research based on the fact that sand is a discrete material and analysis the arrangement and movement of particle on meso-scale.Therefore,following numerical simulations are implemented in this paper:(1)using numerical simulation software PFC to simulate a series of routine test and compare them with laboratory tests;(2)the numerical simulations of the cyclic biaxial test of disc particle,unbroken non-circular particles,and broken particles was performed.Measure and analyze the effects of different factors on the liquefaction;(3)the standard deviation of porosity is used to describe the large deformation after liquefaction,and the monitoring of this parameter is achieved through a process developed independently.Through the researches above,it is demonstrated that numerical simulation can reflect the characteristics of the real sand,and the effects of various factors on the sand liquefaction in the liquefaction process are analyzed.At the same time,it is found that the standard deviation of porosity has a good correlation with the post-liquefaction large deformation of sand,which reveals the essence of the sand liquefaction and the meso-mechanism of post-liquefaction large deformation. |
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