含应力旋转路径条件下黏土非共轴变形特性

Non-coaxial Deformation Behavior of Clay with Various Stress Rotation Paths

利用空心圆柱扭剪仪对不同含应力旋转路径条件下黏土的非共轴变形特性开展了研究。试验应力路径包括:主应力方向单纯旋转、主应力方向往复循环旋转以及旋转的同时增加剪应力,分析了主应力系数、剪应力水平、应力旋转方向及其与剪应力耦合作用对黏土非共轴特性的影响。试验结果表明:各类含应力旋转路径都会引起原状黏土相应的变形累积,中主应力系数及剪应力值对应变的开展都有一定的影响。不同主应力方向旋转路径引起的主应变增量方向都与主应力方向存在显著的非共轴现象。排水条件、中主应力系数、循环次数对黏土非共轴特性的影响较小,剪应力值较小时非共轴现象更为显著,主应力旋转方向反向时,非共轴角会随之发生突变,应力旋转路径是决定黏土非共轴变形规律的主要因素。

The non-coaxial deformation behavior of intact clay subjected to different stress rotation paths is studied using a hollow cylinder torsion shear apparatus.The stress paths with pure principal stress rotation,cyclic principal stress rotation and principal stress rotation combined with shearing are considered in the test.The influences of intermediate principal stress coefficient b,shear stress level q,stress rotation direction and the combining effect with shearing on the non-coaxial behavior of clay are analyzed.The test result indicates that（1） deformation accumulation was induced in the intact clay by various stress rotation paths,both b and q have certain influence on the strain development;（2） all the directions of principal strain increment induced by various principal stress rotation paths are non-coaxial with the direction of principal stress;（3）the effects of drained condition, rotation cycles and b on the non-coaxial behavior of intact clay are unobvious,the Non-coaxial phenomenon behaves more significant with smaller shear stress,the non-coaxial angle changes suddenly when the principal stress rotates in the reverse direction.The stress path is considered as the main factor of controlling the non-coaxial deformation behavior of intact clay.