【摘要】 复杂应力状态下岩石破坏特性的精确描述对于岩土工程结构设计具有重要的意义.基于多种岩石不同受力形式下的试验结果,将岩石的破坏形式分为拉断、局部剪切破坏和整体剪切破坏,使用应力三维度作为应力状态参数,分析岩石的破坏形式及不同破坏形式下强度参数随应力状态的变化规律.结果表明:对同种岩石,随应力三维度代数值减小,其破坏机理由拉断逐渐变化为局部剪切破坏和整体剪切破坏,三种破坏形式之间存在两个应力三维度分界值.对三种破坏形式,控制断裂发生的主要因素也不同.拉断主要受最大拉应力控制,局部剪切破坏由最大切应力主导,但同时受体变应力的影响,而整体剪切破坏仅由最大切应力控制.因此针对三种破坏形式,分别选择控制破坏的参量,提出破坏判据,并通过煤样和大理岩的单轴和三轴压缩试验结果验证了判据的正确性.更多还原

【Abstract】 The accurate characterization of failure of rocks in complicate stress states has important implications for the design of the geotechnical engineering structure.Based on many experimental results of several types of rocks under different loading conditions,failure modes of rocks are divided into three types including tension fracture,local shear failure,and general shear failure.The stress triaxiality is introduced to reveal stress states of different loading conditions,and then the change rules of failure mode and strength parameter with different stress states are analyzed in detail.The results have shown that for a given rock material,with the stress triaxiality decreasing,the failure mechanisms will change from tension fracture to local shear and general shear failure gradually,and two demarcation points of stress triaxiality exist between these three failure modes.The controlling parameters which dominate these three failure mechanisms are also different,and it is impossible to capture all features of failure under different stress states with a single criterion,and different functions are necessary to predict failure of different mechanisms.Tension fracture is dominated by the maximal tensile stress,local shear failure is dominated by the maximal shear stress,and influenced by the stress triaxiality,and general shear failure is only controlled by the maximal shear stress.Therefore,different parameters which dominate these three failure modes are taken account respectively,and the failure criteria corresponding to these three failure modes are developed and presented to evaluate the failure behavior of rocks under various complicate stress states.Furthermore,the predictions of failure criteria are compared to published experiment data of coal and marble under axial compression and conventional triaxial compression tests.The comparison indicates that the newly proposed failure criteria give consistent results for both rocks in a range of stress triaxiality from uniaxial to triaxial compression.更多还原