The mechanical properties of lunar soil simulant which is used as the bed material of the model test for the lunar exploration

directly affect the design of structures like lunar probe and lander

and the shear strength is one of the main mechanical properties. To determine the mechanical properties of TJ-1 lunar soil simulant used in soft-landing model tests

a series of triaxial tests with triaxial apparatus under standard stress path is carried out to obtain its stress-strain relationship curves for different relative densities

shear rates and confining pressures. The result shows that

TJ-1 lunar soil simulant possesses the characteristics of strain softening and an apparent cohesive force of certain values

the peak inner frictional angle lies in the range of 43°-51°. With the increase of relative density of lunar soil simulant

the characteristics of strain softening grows more obvious and the values of cohesive force and angle of internal friction become greater; meanwhile

the values of shear strength indices decrease generally when the loading rates becomes faster. A numerical model of triaxial test using PFC3D is established to study the effect of meso parameters

such as inter-particle frictional coefficient

initial porosity and particle stiffness on the shear strength indices of lunar soil simulant. The simulation turns out that the inter-particle frictional coefficient is the primary factor affecting the angle of internal friction

while the other two have less effect. Within a certain limit value

the inter-particle frictional coefficient increases approximately linearly with the angle of internal friction.