复杂应力条件下饱和南京细砂门槛剪应变特性

摘要

Using GDS dynamic hollow cylinder torsion apparatus( HCA), a series of cyclic torsional triaxial tests under complex initial consolidation condition were performed on saturated Nanjing fine sand while Dr = 50％.The effect of the initial principal stress direction ( α0 ), the initial ratio of deviatoric stress (η0), the initial average effictive principal stress (P0),and the initial intermediate principal stress parameter ( b0 ) on the threshold shear strain (γt) of saturated Nanjing fine sand were systematically studied.The results show that γt increases with the increase of η0, P0, and b0 when the other three parameters keep constant.α0 have a great influence on reducing γt,when α0 increases from 0° to 45°; γt increased, when α0 increases from 45° to 90°.The effect of α0 on γt play a leading role and the effect of η0 is weakened while α0 about 45°.%利用GDS空心圆柱扭剪(HCA)仪,对相对密度Dr=50%的饱和南京细砂进行三向非均等固结条件的循环扭剪试验,研究初始主应力方向角(αo)、初始偏应力比(ηo)、初始平均有效主应力(po)和初始中主应力参数(bo)4个初始固结应力参数对门槛剪应变(γt)的影响.研究结果表明:当其余的3个初始固结应力参数不变时,γt随着任一参数η0po、或bo的增大而增大;αo对γt的影响较大,且当αo从0°到45°的增大过程中,γt逐渐变小;当αo从45°增大到90°的过程中,γt逐渐变大;当αo≈45°时,主应力方向对γt的影响起主导作用,偏应力比的影响被弱化.