考虑温度影响的高庙子膨润土强度与变形特性试验研究

Strength and volume change of buffer material under high temperature and pressure

为了探讨温度对高庙子膨润土的强度和变形特性的影响,使用高温高压土工三轴仪,共做81个高压高温高庙子(GMZ)膨润土的三轴不排水剪切试验,系统分析干密度、围压、温度和含水率对高庙子膨润土强度与变形特性的影响。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;无围压及较高干密度时试样均呈现脆性破坏,较高围压和较低干密度时,试样主要呈塑性破坏;(2)高庙子膨润土的强度随含水率增大而减小;较低干密度时,偏应力–轴向应变曲线的位置随温度升高而上移;但较高干密度时的情况则完全相反;(3)初始杨氏模量在干密度较低时随温度升高呈现增加的趋势,而在干密度较高时则相反;随着含水率的升高,初始杨氏模量总体上不断减少;(4)随着温度升高,泊松比增加;干密度和含水率对泊松比的影响不大;(5)建立高庙子膨润土的黏聚力和内摩擦角随干密度、含水率和温度变化公式。研究成果可为分析缓冲材料的热–水–力耦合性状提供科学依据。

In order to study the deformation and strength characteristics of GMZ bentonite under high temperature and high pressure,undrained triaxial shearing tests were conducted to 81 specimens with the high-pressure triaxial apparatus with temperature control. The influences of dry density,confining pressure,temperature and water content on deformation and strength characteristics of GMZ bentonite were investigated. The results show that the failure forms of GMZ bentonite were significantly influenced by confining pressure and dry density. The specimens tested under unconfined conditions were all in brittle failure. The specimens with low dry density underhigh confining pressure exhibited largely the plastic failure,while those with high dry density exhibited brittle failure. The strength of GMZ bentonite specimens decreases with the increasing of water content. The influence of temperature and dry density on strength is complex. The position of deviator stress-axial strain curves rises with the increasing of temperature for specimens with low dry density,but it behave oppositely for specimens with high dry density. The initial Young＇s modulus of the specimen with low dry density also rises with the increasing of temperature,but it＇s opposite for specimens with high dry density. The initial Young＇s modulus of specimens generally decreases with the increasing of water content. Poisson＇s ratio gradually decreases with the increasing of confining pressure for specimens with low dry density,but this tendency is not obvious for specimens with high dry density. Poisson＇s ratio is less influenced by temperature and water content. The formulae of cohesion and internal friction angle changing with dry density,water content and temperature were established for GMZ bentonite specimens.