大主应力方向及中主应力系数对重塑黄土小应变刚度特性影响试验研究

利用配备高精度应变传感器的空心圆柱扭剪仪对重塑黄土开展了一系列定向剪切试验，剪切过程中保持平均主应力p、大主应力方向角? 以及中主应力系数b不变。共完成了包括3组不同大主应力方向角和1组不同中主应力系数的4组试验，共21个试样。对定向剪切条件下重塑粉土的应力-应变-强度以及小应变（<0.1%）刚度特性进行了研究，分析了不同大主应力方向角及中主应力系数的影响。试验研究结果表明，重塑黄土存在显著的强度各向异性特性，沿? =0°方向的强度最大，而最小强度方向因中主应力系数的不同而不同。? =0°时，b=0.25的强度最大，此时试样接近平面应变条件。小应变条件下重塑黄土的剪切刚度也因剪切时?和b的不同而不同，剪应变小于0.02%和大于2%时，刚度基本保持不变，初始剪切刚度很大，当剪应变大于0.02%后，随着剪应变的增加而迅速衰减，衰减曲线可以采用指数函数进行较好的拟合。

Influence of principal stress direction and intermediate principal stress parameter on the small strain stiffness of reconstituted loess

A series of tests was carried out on reconstituted loess with a hollow cylinder apparatus equipped with high precision strain sensors with fixed principal stress direction. The mean principal stress p, principal stress direction ? and intermediate principal stress coefficient b were constant during shearing. A total of 21 specimens in 4 groups of experiments, including 3 groups with different main stress direction angles and 1 group with main stress coefficients, were completed. The stress, strain, strength, and small strain (2%. The initial stiffness was higher at the beginning of shearing and decreased quickly with the increasing of shear strain when shear strain >0.02%. Stiffness varying with shear strain could be simulated accurately with the exponential function.