大理岩加、卸荷破坏过程的三维颗粒流模拟

从大理岩常规三轴加、卸荷室内试验出发，结合PFC3D颗粒流程序进行分析，在明确室内试验与数值模拟试验卸荷速率对应关系的基础上，对不同卸荷速率下试样破坏过程的力学特性及破坏机制进行探讨。结果表明：加、卸荷路径下整个加载过程中张拉裂纹数量均明显高于剪切裂纹；常规三轴试验损伤应力之后，裂纹围绕某一速率进行扩展，卸荷试验损伤应力之后，裂纹的发展是突发性的；不同应力路径下试样损伤破坏的差异性主要形成于损伤应力至峰值应力这一阶段，直至卸荷速率超过6 MPa/s，试样的损伤程度与破坏形式逐渐趋于一致；随着围压的增大，不同卸荷速率下岩石破坏均呈现出由张拉破坏逐渐向剪切破坏过渡。

3D particle flow simulation of loading-unloading failure process of marble

Combing with the PFC3D software, the conventional triaxial loading and unloading tests were carried out on marble specimens in the laboratory. Then the results of unloading rate were compared between the numerical simulation and lab test. According to the crack propagation in mesoscale, the mechanical properties and failure mechanism of specimens under different unloading rates were discussed. The results show that the number of tensile cracks on specimens was obviously higher than that of shear cracks at the loading stage in the loading and unloading process. The crack propagated at a certain rate after the conventional triaxial test damage stress, while the crack developed suddenly after the unloading test damage stress. Under different stress paths, the difference of damage failure between the damage stress and the peak stress was mainly formed in the stage from damage stress to peak stress. The damage degree and failure form of the specimen tended to be consistent until the unloading rate beyond 6 MPa/s. With the increase of the confining pressure, rock failure showed a transition from tensile failure to shear failure at different unloading rates.