粉砂质泥岩三轴压缩应力松弛本构模型研究

摘要

The stress relaxation test of saturated silty mudstone under triaxial compression was performed with the RLJW-2000 rock servo-controlled rheology testing machine through step loading.By analyzing the characteristics of test curves,it is shown that the viscoelastic model can be used to describe the stress relaxation properties of silty mudstone.Burgers model was firstly selected to identify the stress relaxation of silty mudstone.Then two-element,four-element and six-element generalized Maxwell models were also applied in the identification.The parameters of these four models under different strain levels were obtained.According to the identification results,advantages and disadvantages of each model were analyzed and evaluated,and some conclusions were drawn.Logically,six-element generalized Maxwell model can describe accurately the stress relaxation properties of silty mudstone,but from the view point of engineering practice,two-element generalized Maxwell model is more suitable than other models to reveal the stress relaxation properties of silty mudstone.%采用RLJW-2000型岩石三轴流变伺服仪,在分级加载条件下完成了饱和粉砂质泥岩的三轴压缩应力松弛试验。依据试验结果,分析了岩石应力松弛曲线的特征,表明可以用黏弹性模型来描述粉砂质泥岩的应力松弛特性。分别采用Burgers模型,二单元、四单元以及六单元广义Maxwell模型对各级应变水平下的试验曲线进行辨识研究。依据辨识结果,比较了各模型的优缺点,结果表明：六单元广义Maxwell模型可以准确描述粉砂质泥岩的应力松弛特性;从工程应用角度来讲,采用二单元广义Maxwell模型来描述粉砂质泥岩的应力松弛特性是较适宜的。