煤系砂岩真三轴试验及细观模拟研究

True Triaxial Test and Mesoscopic Simulation of Coal Measures Sandstone

研究真三轴应力状态下岩石变形破坏特征及其机理,对于深地工程研究有着极高的指导价值与现实意义,结合室内真三轴试验,通过颗粒流离散元程序PFC^(3D)对真三轴应力状态下岩石的变形破坏过程进行了细观数值计算分析。研究发现:随着中间主应力的增加,煤系砂岩强度呈先增加后减小的趋势,对比数值模拟结果则为随着中间主应力的增加,拉黏结破坏百分比呈先减小后增大的趋势。岩石破坏是由其内部大量微裂纹拉伸扩展连接所引起的,往往剪切裂纹出现伴随有大量的张拉裂纹;同时总黏结破坏数曲线拐点的变化说明,中间主应力在真三轴试验条件下对岩石的破坏先起保护作用随后起加剧破坏作用。

The study of the characteristics and mechanism of rock deformation and failure under true triaxial stress state has a very high guiding value and practical significance for the research of underground engineering.Combined with the true triaxial test in the laboratory,the mesoscopic numerical analysis of the rock deformation and failure process under true triaxial stress state was performed through the particle flow discrete element program PFC3 D.The study found that with the increase of the intermediate principal stress,the strength of coal measures sandstone firstly increased and then decreased.The comparison numerical simulation results showed that with the increase of the intermediate principal stress,the percentage of failure of the tensile bond decreased firstly and then increased.The rock failure was caused by a large number of micro-cracks stretching and expansion joints inside,and often a large number of tensile cracks occured along with the shear cracks.At the same time,the change of the inflection point of the total cementation failure curve indicated that under true triaxial test conditions the intermediate principal stress firstly played a protective role and then a more destructive role for the destruction of the rock.