高庙子膨润土在高温高压下的强度特性研究

高庙子膨润土是中国高放废物地质库的首选缓冲/回填材料,将长期在高温(100℃左右)高压(数十兆帕)条件下工作。为了探讨高庙子膨润土在高温高压条件下的强度特性,使用高温高压土工三轴仪,共做了81个三轴不排水剪切试验,系统研究了干密度、围压、温度和含水率对其强度特性的影响。研究结果表明:(1)围压和干密度对高庙子膨润土的破坏形态的影响很大;(2)高庙子膨润土的强度随含水率增大而减小;温度和干密度对其强度的影响比较复杂,干密度较低时,偏应力–轴向应变曲线的位置随温度升高而上移;但干密度较高时的情况则完全相反;(3)分别建立了高庙子膨润土的黏聚力和内摩擦角随干密度、含水率和温度变化的公式。本文的研究成果为分析缓冲材料的热–水–力耦合性状提供了科学依据。

Strength properties of GMZ bentonite under high temperatures and pressure

GMZ bentonite is the first selection of buffer/backfill material for geological disposal repository of high-level radioactive waste in china. It will work under high temperature and high pressure for a long time. In order to investigate the strength characteristic of GMZ bentonite under high temperature and high pressure, 81 undrained triaxial shearing tests were conducted by using the high-temperature and high-pressure triaxial apparatus, and the effect of dry density, confining pressure, temperature and water content on its strength characteristic were systematically analyzed. The result shows that (1) confining pressure and dry density have a great influence on the failure forms of GMZ bentonite; (2) The strength of GMZ bentonite decrease with the increase of water content; The influence of temperature and dry density on its strength is complex, the position of deviator stress-axial strain curves are rising with the increase of temperature in low dry density, but it’s on the contrary in high dry density; (3) The formula of cohesion and internal friction angle with the changing of dry density, water content and temperature of GMZ bentonite are established, respectively. The research results of this paper provide a scientific basis for analyzing the thermos-hydro-mechanical coupling characteristics of buffer materials.