Deformation behaviors of TJ-1 lunar soil simulant during excavation

Torsion shear tests are conducted by use of a dynamic hollow cylinder apparatus in Tongji University on the TJ-1 lunar soil simulant subjected to stress paths of excavation in order to investigate its deformation behaviors and non-coaxiality during the excavation under the earth environment. The test results indicate that (1) the stress path significantly affects the deformation behaviors of the TJ-1 lunar soil simulant; (2) the soils at the bottom of the pit and outside the diaphragm walls fail due to large deformation; (3) the soils at the bottom exhibit a tendency of contraction; (4) the soils adjacent to the diaphragm walls show remarkable non-coaxiality due to the coupled effects of stress ratio, rotation amplitude and rotation rate of the principal stress; and (5) the non-coaxiality of soils at the bottom of the pit is mainly affected by the rotation amplitude and rotation rate of the principal stress direction, while the non-coaxiality of soils outside the wall is controlled by the stress ratio, rotation amplitude and rotation rate of the principal stress direction.