基于Lemaitre原理改进砂岩蠕变损伤模型研究

以煤矿巷道围岩（砂岩）为研究对象，采用MTS815.02岩石力学试验系统，对流固耦合蠕变过程中孔隙水压力作用机制展开研究，以伯格斯模型为基础，基于Lemaitre原理建立改进的伯格斯非线性蠕变损伤模型，可以得到如下主要结论：当围压越大，岩石蠕变最后一级荷载作用持续时间越长，相对经历衰减蠕变和稳定蠕变时间越长；且由最终一级破坏蠕变变形值可知，孔隙水压较小时，蠕变变形量相对较大，此时围压增大提升了岩石延性特性，但是孔隙水压增大却削弱了围压作用，由于孔隙水压使得岩石力学性能劣化，因而减少了岩石在破坏时蠕变变形量；随后基于Lemaitre原理建立的伯格斯非线性损伤蠕变模型，可以较好地描述岩石的衰减蠕变、稳定蠕变与加速蠕变阶段；且试验曲线与拟合曲线吻合度高，验证了本文所建立损伤流变模型的合理性．

Study on the Creep Damage Model of Sandstone Based on the Principle of Lemaitre Improvement

In this paper, the rock (sandstone) surrounding the coal mine roadway is investigated. The MTS815.02 rock mechanics test system is used to study the pore water pressure mechanism during the fluid-solid coupling creep process. Based on the Boggs's model, the improved Boggs nonlinear creep damage model is established using the Lemaitre principle. Some main conclusions are drawn as follows: with a greater confining pressure and a longer duration of the last level load of the creep, , the rock will experience longer decay creep and steady creep time. From the value of the final-staged damage creep deformation, the creep deformation is relatively larger for a smaller pore water pressure. The increase of confining pressure enhances the ductility of the rock, but increase of the pore water pressur undermines the effect of the confining pressure. As the pore water pressure deteriorates the mechanical properties of rocks, the creep deformation of rock at failure is reduced. The Burgess nonlinear creep damage model established from the Lemaitre principle can well describe the decay creep, the steady creep and the accelerated creep stages of the rocks. It is found that the fitted curves match the test curves, verifying the rationality of this damage rheological model.