主应力方向和偏应力比对TJ-1模拟月壤各向异性的影响

Effects of principal stress direction and deviatoric stress ratio on anisotropy of TJ-1 lunar soil simulant

采用空心圆柱扭剪仪对干燥TJ-1模拟月壤试样进行了应力主轴固定的定向剪切试验及不同偏应力比时主应力方向的纯旋转试验。从应力-应变关系角度出发,研究主应力方向、偏应力比对其各向异性的影响,并探讨了上述因素对TJ-1模拟月壤非共轴性的影响。试验结果表明:主应力方向和偏应力比对TJ-1模拟月壤的各向异性均有显著影响;应力主轴旋转引起的非共轴现象比定向剪切时明显,且偏应力比较小时非共轴角随应力主轴旋转呈先减小后增加的趋势,偏应力比较大时非共轴角一直减小直至试样破坏时非共轴现象消失。上述成果可弥补干砂试样非共轴领域的研究空白,并可望为将来月球上基础设施的修建提供技术支持。

The hollow cylinder apparatus at Tongji University was used to conduct the torsional shear test on the dry TJ-1 lunar soil simulant by applying fixed and rotated principal stress axes.In the perspective of the stress-strain response,the investigation is focused on the effect of the principal stress direction and the deviatoric stress ratio on the anisotropy of the dry TJ-1 lunar soil simulant.In addition,their impact on the non-coaxiality of the specimen is also further explored.The test results indicate that the principal stress direction and the deviatoric stress ratio significantly affect the anisotropic behavior of the TJ-1 lunar soil simulant.The non-coaxiality observed in the torsional test with rotated principal stress direction is more remarkable than that in the tosional test with fixed principal stress direction.In the test with rotated principal stress direction,the non-coaxial angle decreases and then increases at a small deviatoric stress ratio;while the angle continuously decreases at a high eviatoric stress ratio and diminishes as the specimen failure.This study will help to fill the gap in the research with emphasis on anisotropic behaviors of dry sands;and it also provides necessary theory beneficial to the future development of human infrastructure on the Moon.