主应力轴旋转条件下初始应力状态对冻结黏土动力特性的影响试验研究

Experimental study on the influence of initial stress state on the dynamic characteristics of frozen clay under principal stress rotation

为了揭示主应力轴旋转条件下初始应力状态对冻结黏土动力特性的影响,利用冻土空心圆柱仪实现了纯主应力轴旋转的圆形应力路径,在圆形应力路径基础上开展了一系列室内空心扭剪试验,研究了初始应力状态对冻结黏土累积塑性应变、应力-应变滞回圈和动模量的影响。结果表明:纯主应力轴旋转条件下试样承受的初始应力越大时,冻结黏土空心圆柱试样的累积塑性应变发展速率越快,产生的最终累积塑性应变也相对较大。另外,发现纯主应力旋转条件下随着初始应力的增大,冻结黏土试样轴向应力-应变和剪切应力-应变滞回曲线倾斜度增大,冻结黏土试样的轴向回弹模量和剪切模量也增大,且不同循环应力比下轴向回弹模量和剪切模量与静偏应力比之间呈线性关系。研究结果有助于完善寒区工程和人工冻结工程设计理论。

In order to reveal the influence of the initial stress state on the dynamic characteristics of frozen clay under the condition of principal stress shaft rotation,a circular stress path of pure principal stress rotation was re⁃alized by using the frozen hollow cylindrical apparatus(FHCA),and a series of hollow torsional shear tests in laboratory were carried out on the basis of the circular stress path,and the effects of the initial stress state on the cumulative plastic strain,stress-strain hysteresis loop and dynamic modulus of frozen clay were studied.The re⁃sults show that the greater the initial stress of the specimen under the condition of pure principal stress rotation,the faster the cumulative plastic strain development rate of the frozen clay hollow cylindrical specimen,and the greater the final cumulative plastic strain generated.In addition,it is found that with the increase of the initial stress under the pure principal stress rotation condition,the inclination of the axial stress-strain and shear stressstrain hysteresis curves of the frozen clay specimen increases,and the axial resilience modulus and shear modu⁃lus of the frozen clay specimen also increase,and there is a linear relationship between the axial resilience modu⁃lus and shear modulus and the static deviation stress ratio under different cyclic stress ratios.This research re⁃sults are helpful to improve the design theory of cold region engineering and artificial freezing engineering.