岩石裂纹扩展-破断规律及流变特征

Propagation-coalescence and rheologic fracture behavior of rock cracks

讨论岩石断裂力学研究近年来的若干进展,主要内容包括扩展机理、断裂准则、实验加载方式与裂纹定位方法、数值计算方法在岩石断裂力学研究中的应用。基于室内实验研究单轴加载下预制裂纹间的贯通模式与多裂纹试样的破坏模式、压剪复合作用下混合裂纹间的贯通类型与破碎规律。与此同时,针对岩石亚临界裂纹扩展问题进行相关讨论并给与实例分析。结果表明:处于同一应力水平时,水岩化学作用能加速亚临界裂纹扩展;水化学腐蚀后岩石的断裂韧度均小于其在空气中的断裂韧度。此外,还对岩石流变断裂模式及考虑原生裂隙的非线性流变模型进行分析:结合岩石断裂力学与流变力学推导出压剪应力环境下裂纹流变断裂判据与理论模型;引入损伤因子和裂隙塑性体构建了能描述原生节理影响的岩体非线性蠕变模型。最后,展望岩石断裂力学未来的发展前景,并就岩石裂纹萌生与扩展的研究阐述几点认识。

The recent developments in some aspects on the research of rock fracture mechanics were discussed,including the crack extension mechanism,fracture criterion,loading method,locating method of crack and numerical method in rock fracture.At the same time,case studies about crack propagation,subcritical crack growth and creep fracture criterion and theoretical model were accomplished.Firstly,based the uniaxial test of rock-like specimens,the coalescence pattern between fissures and failure modes of multi-fissure specimens was discussed.At the same time,further discussion about the coalescence patterns and fragmentation of mixed crack specimen under compressive-shear test were made.Moreover,the subcritical crack growth,and fracture toughness in three different kinds of nature rocks were investigated with double torsion test.The results show that:at the same stress level,the water-rock interaction can accelerate the subcritical crack growth and the fracture toughness of rocks under atmospheric environment is higher than that of rocks immersed in water.In addition,the creep fracture criterion and nonlinear elastic visco-plastic creep damage models were also analyzed:combined with rock fracture mechanics and rheological mechanics,the theoretical models of crack rheologic fracture failure under compressive-shear load were established.By introducing damage factor and plastic body containing fissures,the nonlinear elastic visco-plastic creep damage model was conducted.Finally,several understandings on the research work were presented in prospect of the fracture mechanics in the future.