关键词: 月壤, 离散单元法, 水平推剪试验, 抗转动作用, 范德华力

Abstract: A discrete element method (DEM) contact model for lunar soil taking rolling resistance and van der Waals forces into consideration is used to simulate the horizontal pushing test, which is a simplified machine-lunar soil interaction problem. The soil failure mechanism and the effects of excavation blade depth, inclination and speed are analyzed; and some suggestions for real lunar excavation are offered. The results show that the pushing resistance increases with pushing displacement to a peak state rapidly and then tends to be stable after a sharp declination. With the accumulation of soil heap in front of the blade, the pushing resistance increases slowly again. The pushing resistance, energy consumption and the affected area are greater under larger pushing depth while the slip surfaces are all straight. As the pushing inclination increases, the pushing resistance, energy consumption and the affected area decrease; and the slip surface remains straight. The pushing resistance, energy consumption and affected area increase with the speed. Since the pushing resistance is provided by frictional force between the machine and lunar ground, which is proportional to the weight of an excavator; it is recommended that shallow, inclined and slow excavation should be used in early-stage lunar base construction. This scheme is advantageous in its low demand for the mass of the excavation machine, thus reducing the mass launched from the earth to the moon.

Key words: lunar soil, discrete element method, horizontal pushing test, particle rolling resistance, Van der Waals forces