复杂加卸荷条件下岩石破裂面三维形貌演化特征与破坏孕育机制研究

Rock failure mechanism is effected by loading stress path. Whether rock failure or not is determined by stress state and unloading velocity. There is relationship between rock fracture morphology and unloading failure mechanism.Triaxial loading and unloading test, 3D morphology analysis and mesoscopic numerical analysis will be conducted under different stress paths. The relationship between the characteristics of facture morphology,stress path, unloading velocity and confining pressrue are discussed. The mechanism of rock failure and energy dissipation is analyzed.The relationship between rock mesoscopic rupture mode and microscopic rupture mechanism is studied. Rock failure constitutive model is generalized according to the characteristics of fracture morphology, which reflects the change of stress path. Rock failure evolution is described by the change of volume strain. Based on principle of minimum potential energy, the expression of mechanical criterion is put forward. The results should agree well with laboratory test. All these results have a great theoretical and practical value for deepening research of rock failure mechanism, predicting and preventing rock disasters.

岩体的变形破坏机制受其开挖受荷的应力路径影响，实际工程岩体是否发生破坏及何时发生破坏与岩体的应力状态和应力降速度密切相关，研究表明岩石破裂面的三维形貌信息与岩石卸荷破坏机理、本构有内在联系。项目开展不同应力路径下的三轴加卸荷实验，通过对不同实验条件下岩石破裂断口的三维激光扫描实现破坏断面的三维可视化，结合三维颗粒流细观模拟仿真，建立断口三维形貌参数与岩石破坏特征、应力路径、卸荷速度及围压的关系，揭示岩石变形破坏过程中的能量积聚、耗散和释放机制，探索岩石的细观断裂机制与宏观破坏特征之间的相应关系。结合破坏面的三维可视化信息，构建能反映应力路径变化的硬质岩石弹脆性本构模型，给出以体积应变表征的岩石裂纹形成演化的定量描述方法。根据最小势能原理，提出不同应力路径下岩石破坏的力学判据，并经实验结果验证。研究成果对于深化岩体破坏机理认识、预测与防治岩体灾害具有重要的理论与工程意义。

岩石破裂面的三维形貌信息与岩石卸荷破坏机理、本构有内在联系。项目开展不同应力路径下的三轴加卸荷实验，通过对不同实验条件下岩石破裂断口的三维激光扫描实现破坏断面的三维可视化，结合三维颗粒流细观模拟仿真，建立断口三维形貌参数与岩石破坏特征、应力路径、卸荷速度及围压的关系。卸荷速率增大，破坏时的轴向应力、轴向应变减小，岩样的破坏形式由张拉剪切破坏向剪切破坏过渡。环向变形和体积变形对卸荷围压的变化更敏感，卸荷破坏是体积扩容所致。破裂面分形维数值与峰值强度、破坏强度、残余强度呈负相关关系，其中与峰值强度相关性最强。基于破裂面宏细观特征信息确定了岩体动力失稳弹性能释放终止点位置。弹性能释放量图解中蕴含着丰富的信息量，使对岩体动力失稳过程弹性能释放特征描述图像化。.研究成果对于深化岩体破坏机理认识、预测与防治岩体灾害具有重要的理论与工程意义。