主应力轴旋转条件下冻结黏土的动强度特性北大核心CSCD

研究冻土动强度对寒区工程和人工冻结工程施工及安全性评价具有重要意义。为了揭示主应力轴旋转对冻结黏土动强度特性的影响,利用空心扭剪仪开展不同围压下冻结黏土动三轴和空心扭剪试验,探讨了主应力轴旋转对冻结黏土动强度、动黏聚力和动内摩擦角变化规律的影响。结果表明:主应力轴旋转导致冻结黏土试样的动强度降低,围压越低主应力轴旋转对动强度影响效果就越明显;随着震动次数的增多,主应力轴旋转条件下冻结黏土动黏聚力衰减速度相对于主应力方向固定时加快;不同于主应力轴方向固定条件下动内摩擦角随震动次数增多而衰减的特点,在主应力轴旋转条件下动内摩擦角随震动次数增多而增大。另外,研究显示主应力轴旋转条件下动强度、动黏聚力和动内摩擦角均与震动次数的对数呈良好的线性关系,用线性方程对其进行了拟合,并给出拟合系数和确定系数。

Dynamic strength characteristics of frozen clay under rotation of principal stress axis

Deep studying the dynamic strength of frozen soil is of great significance to the construction and stability evaluation of cold region engineering and artificial freezing engineering. In order to reveal the effect of rotation of principal stress axis on dynamic strength characteristics of frozen clay， dynamic triaxial and hollow torsional shear tests of frozen clay under different confining pressures were carried out by using a frozen hollow cylinder （FHCA-300）. And the effects on dynamic strength， dynamic cohesion and dynamic internal friction angle of frozen clay were discussed. The results show that rotation of principal stress axis reduces the dynamic strength of frozen clay specimens， and the lower the confining pressure is， the more obvious the effect is. Under the condition of rotation of principal stress axis， the attenuation rate of dynamic cohesion of frozen clay with number of vibrations is faster than that with fixed principal stress axis direction. Different from the characteristics that the dynamic internal friction angle decreases with the increase of number of vibrations under the fixed direction of principal stress axis， the dynamic internal friction angle increases with the increase of number of vibrations under the condition of rotation of principal stress axis. In addition， it is found that the dynamic strength， dynamic cohesion and dynamic internal friction angle have a good linear relationship with the logarithm of number of vibrations under the condition of rotation of principal stress axis. The linear equations were used to fit them respectively， and the fitting coefficients and determination coefficients were given.