粉砂质泥岩三轴压缩应力松弛特性试验研究

 采用RLJW–2000型岩石三轴流变伺服仪，在分级加载条件下完成饱和粉砂质泥岩的三轴压缩应力松弛试验。基于试验结果，划分岩石的应力松弛阶段，分析岩石的应力松弛特征，研究不同应变水平下岩石的应力松弛速率、径向应变、体积应变以及松弛模量随时间的变化规律，探讨岩石应力–应变等时曲线特征，系统地揭示粉砂质泥岩三轴压缩应力松弛特性。选取Burgers模型来描述粉砂质泥岩的应力松弛特性，采用LM-NLSF法对模型参数进行辨识。对比模型拟合曲线与试验曲线，二者吻合较好，表明Burgers模型可以较好地描述粉砂质泥岩的应力松弛特性，辨识得出的模型参数具有一定的实用价值。

EXPERIMENTAL INVESTIGATION ON STRESS RELAXATION PROPERTIES OF SILTY MUDSTONE UNDER TRIAXIAL COMPRESSION

The stress relaxation test of saturated silty mudstone under triaxial compression is carried out on the RLJW–2000 rock microcomputer-controlled rheology servo test system by step loading method. Based on the test results，the stress relaxation of silty mudstone is divided into three stages；and the variation laws of stress relaxation rate，radial strain，volumetric strain and relaxation modulus with time are investigated under different strain levels. Moreover，the variation law of stress-strain tautochrone is analyzed. The triaxial stress relaxation properties of silty mudstone is systematically revealed，which provide the fundamental materials for the establishment of silty sandstone?s relaxation models. Burgers model is selected to describe the stress relaxation properties of silty mudstone. Based on the LM-NLSF method，the model parameters under different strain levels are obtained. Comparing testing curves with theoretical curves，it is shown that Burgers model is suitable to describe the stress relaxation properties of silty mudstone；and the obtained parameters have certain practical value.