饱和南京细砂动剪切模量特性的大型振动台试验研究  

Dynamic shear modulus of saturated Nanjing fine sand in large scale shaking table tests

作　　者：陈国兴[1] 王炳辉[1] 孙田[1] 

机构地区：[1]南京工业大学岩土工程研究所,江苏南京210009

出　　处：《岩土工程学报》2012年第4期582-590,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(90715018;51079067);国家重点基础研究发展计划项目(2007CB714200);江苏省高校自然科学重大基础研究资助项目(08KJA560001)

摘　　要：为了研究饱和砂土动剪切模量在振动孔隙水压力(简称孔压)升高和消散阶段的变化规律,开展了饱和南京细砂的大型振动台试验研究。基于试验数据,分析了加速度二次积分时合理选择带通滤波的低频和高频阀值的重要性,提出了由土层加速度时程确定土体动剪切模量的方法。分析孔压升高和消散阶段土体的动剪切模量比与循环周数、孔压比、剪应变幅值的关系,结果表明:与孔压升高阶段相比,孔压消散阶段的动剪切模量比明显要低,将孔压升高与消散阶段的土体动剪切模量视为相同是不合适的;大型振动台试验给出的饱和南京细砂动剪切模量比随剪应变幅值增大而衰减的速度大于室内循环三轴试验给出的结果。In order to investigate the dynamic shear modulus of saturated sand during the increasing and dissipating stages of dynamic pore water pressure （PWP）, large-scale shaking table tests on saturated Nanjing fine sand are carried out. Based on test data, the significance of reasonable choice of the threshold values of low and high frequencies with band-pass filter is analyzed to obtain the displacement from acceleration by double integration. Moreover, an approach to obtain the dynamic shear modulus from the acceleration time-history relationship is established. By analyzing the relationships among the dynamic shear modulus ratio, the cycle number of loading, the PWP ratio and the shear strain amplitudes during the increasing and dissipating stages of PWP, the following results are obtained： （1） since the dynamic shear modulus during the dissipating stage of PWP is significantly smaller than that during the increasing stage, it is unreasonable to take the dynamic shear modulus during the two stages as the same; （2） the decay rate of dynamic shear modulus with the increase of the shear strain amplitude obtained from large-scale shaking table tests for saturated Nanjing fine sand is faster than that obtained from cyclic triaxial tests, in laboratory.

关 键 词：大型振动台试验 饱和南京细砂 动剪切模量 孔压消散 二次积分 

分 类 号：TU435[建筑科学—岩土工程]