Investigation of TJ-1 lunar soil simulant cone penetration tests by calibration chamber under different penetration angles

A series of cone penetration tests on TJ-1 lunar simulant under penetration angles of 0°, 15° and 30° are carried out using the calibration chamber in order to study the engineering properties of lunar soils. The test results show: (1) after the pull-out of cone tip from the ground, the ground surface exhibits different deformation patterns and the deformation area becomes larger and larger as the penetration angle increases. Cylindrical cavity is formed under vertical penetration condition, while ellipsoidal collapse crater appears under inclined penetration conditions; (2) the cone tip resistance increases with the penetration depth under different penetration angles, and it increases linearly with the increase of the penetration angle at the same vertical penetration depth and can be expressed by equation ; (3) the calculation formula can be used to estimate change of the cone tip resistance of vertical penetration with the penetration depth; (4) the horizontal earth pressures around the probe rod increase first and then decrease with the increase of the vertical penetration depth under different penetration angles. The maximum horizontal earth pressure in front of the penetration direction increases linearly with the increase of the penetration angle at the same depth, while that behind the penetration direction presents the opposite trend. They all can be expressed by function ; and (5) the final value of the vertical earth pressure at depth of 600 mm decreases with the increase of the penetration angle, and their relationship fits the equation .