小重力环境下静力触探模型试验研究

Experimental Study on Static Cone Penetration Model Tests under Small Gravity Fields

月球基地建设与矿产资源开发的基础与关键是充分掌握月壤的力学与工程特性。目前由于缺少对小重力环境的真实模拟而难以系统、准确地揭示土的力学、工程等特性与重力场间的耦合环境效应。通过利用磁拟小重力模型试验系统开展了一系列小重力环境(1/6g、1/3g、2/3g、1g)下磁敏性无黏性土静力触探模型试验。试验结果表明:模型探头在贯入过程中锥尖阻力随深度的增加表现出明显的3个应力增长阶段,在同一贯入深度处,锥尖阻力随重力场的增大而增大;归一化锥尖阻力随深度的增加先增大后减小并最终趋于稳定,而随重力场的增大却逐渐减小;同时,归一化锥尖阻力的最大值和最终稳定值与重力场相似常数的倒数间存在较好的线性关系。

The study of mechanical properties of subsurface soils under small gravity fields is the key of lunar base construction and mineral resources exploitation on the moon.At present,it is difficult to systematically reveal the correlations between mechanical/engineering properties of soil and its coupling effects of gravity fields due to the lack of simulation of small gravity fields.A type of magnetic cohesionless soil was adopted to carry out a series of static cone penetration model tests.The tests were conduct under four different gravity fields,including 1/6 g,1/3 g,2/3 g and 1 g(g indicates the earth gravity acceleration)by using the small gravity fields test system.The experimental results show that the cone tip resistance of the model probe in the process of penetration shows three obvious stress growth stages with the increase of penetration depth.At the same depth,the cone tip resistance tends to increase with the increase of the gravity fields.The normalized cone tip resistance increases first and then decreases and eventually stabilizes with the increase of depth,the normalized cone tip resistance decreases with the increase of the gravity fields.At the same time,there is a good linear relationship between the maximum and steady values of the normalized cone tip resistance and the reciprocal of the similarity constant of gravity fields.