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“月壤采样”工程中的关键问题是,月面特殊环境条件下钻取机具与月壤之间的相互作用机制。针对CAS–1模拟月壤在低应力水平下的力学特性,开展直剪、压缩、三轴试验。研究表明:(1)低应力水平下,当孔隙比e=0.8~1.1时,黏聚力c=2.8~5.0 k Pa,内摩擦角?=39.84°~41.09°,压缩曲线表现出先上凹、再下凹的变化特征;当e=0.9~1.1时,初始压缩模量E0=12.647~3.923 MPa,应力–应变曲线分为硬化和软化阶段,软化下降速率较快,残余强度持续时间较长,应力比曲线分布集中。(2)低应力水平下,e越小,峰值偏应力/应力比越大,峰值轴向应变越小,但均在2%~5%范围,残余强度/应力比越大,持续时间越长。(3)初始切线斜率?、峰值应力比?f、残余应力比?r均与围压P0成一定对数线性关系,但在低应力水平下,?下降较慢,初始切线模量Gi(1/?)变化幅度较小,而?f与?r均下降较快。
The key issue in the “lunar soil sampling” project is the mechanism of interaction between the drilling rig and lunar soil under special lunar conditions. According to the mechanical properties of CAS-1 simulated lunar soil at low stress level, direct shear, compression and triaxial tests were carried out. The results show that: (1) At the low stress level, the cohesion c = 2.8-5.0 k Pa and the internal friction angle? = 39.84 ° -41.09 ° when the void ratio e = 0.8-1.1, The initial compressive modulus E0 = 12.647 ~ 3.923 MPa when e = 0.9 ~ 1.1, the stress-strain curve is divided into the hardening and softening stages, the softening descent rate is faster, the residual strength lasts longer, Stress ratio curve is concentrated. (2) Under the low stress level, the smaller the value of e is, the larger the value of peak deviator stress / stress is, and the smaller the peak axial strain is. However, both of them are in the range of 2% ~ 5% and the longer the residual strength / stress ratio, the longer the duration . (3) The initial tangent slope?, Peak stress ratio? F, residual stress ratio? R are all logarithmically linear with the confining pressure P0, but at low stress level, the decrease is slow. The initial tangent modulus Gi /?), But both? F and? R decrease rapidly.