砂土液化后大变形的机理  

Mechanism of large post-liquefaction deformation in saturated sand

作　　者：张建民[1] 王刚[2] 

机构地区：[1]清华大学土木水利学院 [2]二滩水电开发有限责任公司,四川成都610021

出　　处：《岩土工程学报》2006年第7期835-840,共6页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金资助项目(50478016);北京市自然科学基金重点资助项目(8061003)

摘　　要：基于试验观察和机理分析,揭示了不排水往返加载条件下饱和砂土初始液化后的剪切大应变和三个体积应变分量(有效球应力变化引起的体变、可逆性剪切体变和不可逆性剪切体变)之间的内在联系,阐明了三个体积应变分量的组合变化规律控制了饱和砂土液化后大变形的产生和发展,界定了液化后循环剪切大变形过程中交替出现的三种物态(摩擦接触状态、临界接触状态和悬浮状态)及其产生条件,解释了液化后流滑和再固结体变形成的机理,给出了一个物理概念明确并具有普遍性的建立液化后大变形弹塑性本构模型的合理途径。Based on experimental observations and cause analysis of formation, an intrinsic relationship was revealed between the large post-liquefaction shear deformation of saturated sand under undrained cyclic loading and three types of volumetric strain components （i,e,, a reversible component due to dilatancy, an irreversible component due to dilatancy and a component due to change in mean effective stress）. It was found that the development of the large post-liquefaction shear deformation is governed by coupling variation of the three volumetric strain components and is accompanied with three physical states of soil particles （i,e,, the frictional contact state, the critical contact state and the suspension state） that appear altemately. The above new knowledge provides a rational explanation why unstable flow slides and large reconsolidation deformation may take place after the initial liquefaction and also a rational approach to the establishment of an elasto-plastic constitutive model used to describe the large post-liquefaction deformation.

关 键 词：砂土 液化 液化后变形 循环加载 

分 类 号：TU435[建筑科学—岩土工程]