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模拟月壤作为探月工程模型试验的基床材料,其力学特性将直接影响到月球探测器、着陆器等机构的设计,而抗剪强度是其主要力学特性之一。针对软着陆模型试验所用的TJ-1模拟月壤,采用标准应力路径三轴仪对其进行静三轴试验,得到了不同相对密度、剪切速率和围压条件下模拟月壤的应力-应变关系曲线、弹性模量和抗剪强度指标值等,试验结果表明:模拟月壤具有应变软化特征并存在一定大小的表观黏聚力,峰值内摩擦角的值介于43°~51°之间;相对密度越大,应变软化特征越明显,黏聚力和内摩擦角的值都越大:在密实状态时,剪切速率越大,模拟月壤的抗剪强度指标值呈整体下降的趋势。利用PFC~(3D)软件建立三轴试验数值模型,研究了颗粒间摩擦系数、初始孔隙率以及颗粒刚度这3个细观参数对模拟月壤抗剪强度的影响,模拟结果表明:颗粒间摩擦系数是影响抗剪强度指标内摩擦角的主要因素,而初始孔隙率及颗粒刚度的影响则相对不明显;在一定数值范围内,颗粒间摩擦系数越大,内摩擦角的值越大,两者近似呈线性关系。
Simulated lunar soil as a lunar exploration model basement bed material, its mechanical properties will have a direct impact on the lunar probe, lander and other agencies of the design, and shear strength is one of its main mechanical properties. According to the TJ-1 simulative lunar soil used in the soft landing model test, the static triaxial test was carried out by using the standard stress path triaxial apparatus, and the stress-strain of lunar soil under different relative densities, shear rates and confining pressures The relationship curve, the elastic modulus and the shear strength index, etc. The experimental results show that: the simulated lunar soil has the characteristics of strain softening and the apparent cohesion of a certain size, the peak internal friction angle is between 43 ° ~ 51 ° The greater the relative density is, the more obvious the strain softening characteristic is. The larger the values of cohesion and internal friction angle are, the higher the shear rate is, the lower the shear strength index of simulated lunar soil is. trend. A three-axis numerical model was established by PFC 3D software to study the influence of interfacial friction coefficient, initial porosity and particle stiffness on the shear strength of simulated lunar soil. The simulation results show that interparticle friction Coefficient is the main factor that affects the internal friction angle of shear strength index, while the initial porosity and the stiffness of the particles are relatively insignificant; within a certain range of values, the larger the friction coefficient between particles, the larger the value of the internal friction angle, the two The approximate linear relationship.