偏应力比和应力主轴偏转角同时变化下饱和砂土变形特性研究  

Deformation of fully saturated sand under simultaneous variations of deviatoric stress ratio and principal stress rotational angle

作　　者：孙奇[1] 董全杨[2] 蔡袁强[1,2] 王军[2] 胡秀青[2] 

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]温州大学建筑工程学院,浙江温州325035

出　　处：《岩土力学》2015年第8期2261-2269,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51278383;No.51238009;No.51025827;No.51478364);国家重点基础研究发展计划资助(No.2011CB411907);浙江省自然科学基金项目(No.Y1110751);浙江省科技计划项目(No.2010C33182)

摘　　要：利用空心圆柱扭剪仪对饱和砂土进行了应力主轴固定和偏应力比增大（即定向剪切）、偏应力比不变和应力主轴单调旋转（即纯应力主轴单调旋转）、偏应力比和应力主轴偏转角同时增加、偏应力比和应力主轴偏转角分段增加4个系列的排水剪切试验,着重分析不同应力路径下饱和砂土的变形特性及主应力和主应变增量方向变化规律。试验结果表明,纯应力主轴单调旋转下,主应力增量方向在45°~135°范围内变化,主应变增量方向逐渐偏向主应力方向;偏应力比和应力主轴偏转角同时增加下,砂土变形不断增大,当主应力增量方向？？？？45°时,主应变增量方向与主应力增量方向基本一致,但当？？？？45°时,主应变增量方向逐渐偏离主应力增量方向。当应力状态在偏应力比？≤0.75、应力主轴偏转角？≤45°范围内时,体应变、最大剪应变与应力路径无关,且后期纯应力主轴旋转下砂土变形不受前期加载历史的影响。A series of drained shear tests are carried out on saturated sand samples using hollow cylinder apparatus. Four groups of stress paths are considered to study the deformation characteristics of the sand under drained shearing condition, with emphasis on analyzing the variations of the directions of the principal stress increment and strain increment of the sand along various stress paths. The considered stress paths include fixed principal stress directions with increasing of deviatoric stress ratio （shear loading with fixed principal stress directions）, principal stress rotation with constant deviatoric stress ratio （pure principal stress rotation）, simultaneous increase in deviatoric stress ratio and principal stress rotation; multilinear simultaneous increase in deviatoric stress ratio and principal stress rotation. The experimental results indicate that the major principal stress increment direction varies between 45 ° and 135° under the pure rotation of principal stress axes. The major principal strain increment direction moves gradually towards the direction of principal stress. Deformations accumulate under simultaneous increase in stress ratio and principal stress rotation. The direction of principal strain increment coincides with stress increment when α△σ 〈 45 ° , whereas the direction of principal strain increment deviates from stress increment when α△σ 〉 45° . Deformation is practically stress-path independent and the strain response under subsequent principal stress rotation is shown to be independent of the previous loading history, if the final stress state is within the approximate bounds of η≤0.75 and α≤45 ° .

关 键 词：空心圆柱扭剪仪 应力主轴旋转 饱和砂土 应力路径 变形特性 

分 类 号：TU431[建筑科学—岩土工程]