月球极区冻结模拟月壤物理力学特性研究

近年来越来越多的探测结果表明，月球极区永久阴影区月壤中存在水冰。水是人类赖以生存的化学物质，也是理解月球独特的形成与演化过程的关键环节。因此，各航天大国均将月球极区作为探月工程的重要目标。冻结月壤的导热系数和单轴抗压强度是月球极区原位探测取样的基础和关键参数。本研究采用低温试验研究了冻结模拟月壤的导热系数和单轴抗压强度。结果表明：冻结模拟月壤导热系数随含水率增大而线性增大，冻结模拟月壤的导热系数为0.2~1.3 W?m^-1?K^-1。冻结模拟月壤单轴压缩过程中发生脆性破坏，5%含水率冻结模拟月壤单轴抗压强度约为5 MPa，10%含水率冻结模拟月壤单轴抗压强度约为13 MPa。在初始加载阶段，干密度相同、含水率不同的冻结模拟月壤试样因微裂纹压密导致的应变量基本相同；在线弹性阶段，冻结模拟月壤有效弹性模量随含水率增大而增大，其主要原因是含水率增大使得月壤颗粒间的冻结强度增大；在破坏阶段，含水率较高的冻结模拟月壤表现出脆性破坏特征，含水率较低的冻结模拟月壤表现出更显著的塑性特征。研究结果将为月球永久阴影区水冰探测方案制定、探测器研制等提供基础的科学数据支撑。

Study on physical and mechanical properties of frozen simulated lunar soil in lunar polar region

In recent years， more and more detection results show that there is water ice in the lunar soil in the permanent shadow area of the lunar polar region. Water is not only a chemical substance for human survival， but also a key link to understand the unique formation and evolution of the Moon. Therefore， all space powers regard the lunar polar region as an important goal of lunar exploration projects. The thermal conductivity and uniaxial compressive strength of frozen lunar soil are the basis and key parameters of in-situ exploration and sampling in the lunar polar region. The thermal conductivity and uniaxial compressive strength of frozen simulated lunar soil were studied by low temperature test. The results show that the thermal conductivity of frozen lunar soil increases linearly with the increasing of water content. The thermal conductivity of frozen simulated lunar soil is 0.2~1.3 W·m^-1·K^-1. Brittle failure occurs during uniaxial compression of frozen lunar soil. The uniaxial compressive strength of frozen simulated lunar soil with 5% moisture content is about 5 MPa， and that of frozen simulated lunar soil with 10% moisture content is about 13 MPa. In the initial loading stage， the strain caused by micro crack compaction of frozen simulated lunar soil samples with the same dry density and different moisture content is basically the same； In the online elastic stage， the effective elastic modulus of frozen lunar soil increases with the increasing of water content， which is mainly because the water content increase the freezing strength between lunar soil particles； In the failure stage， the frozen simulated lunar soil with high moisture content shows brittle failure characteristics， and the frozen simulated lunar soil with low moisture content shows more significant plastic characteristics. The results will provide basic scientific data support for the formulation of water ice detection scheme and the development of detector in the permanent shadow area of the Moon.