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岩石材料动态力学特性是评价岩石结构在爆炸以及地震载荷作用下稳定性的重要参数 ,是国防和民用防护工程研究的基本资料 ,具有重要的学术价值和应用价值。对花岗岩材料在动态压应力 (单轴和三轴 )作用下的力学特性进行了较系统的实验和理论研究。首先通过实验研究了花岗岩材料的动态断裂特性以及在单轴和三轴动态压应力作用下的强度以及变形特性。结果表明 ,花岗岩的动态断裂韧度随加载速率的增加以及加载时间的减小而增加。在单轴情况下 ,花岗岩的抗压强度随应变速率的增加而增加 ,杨氏模量以及泊松比随应变速率的变化很小。在三轴情况下 ,花岗岩的抗压强度也随应变速率的增加而增加 ,强度的增加幅度随围压的增加有减小的趋势 ,杨氏模量以及泊松比随应变速率的变化不大 ;花岗岩的杭压强度随围压的增加明显增加 ,在不同的应变速率下具有相同的趋势 ,花岗岩的杨氏模量以及泊松比随围压的增加有小幅度的增加趋势。在实验研究的基础上 ,应用滑移型裂纹模型对花岗岩材料在压缩应力作用下的力学特性进行了理论研究。在单轴情况下 ,采用一组与轴向应力平行的滑移型裂纹系列模拟岩石材料的劈裂破坏模式同时考虑裂纹间的相互作用。根据裂纹的动态扩展准则以及能量平衡理论 ,得到了不同应变速率下花岗岩的理论强?
Dynamic mechanical properties of rock material is an important parameter to evaluate the stability of rock structure under explosion and earthquake load. It is the basic data of national defense and civil protection engineering research. It has important academic value and application value. The mechanical properties of granite under dynamic compressive stress (uniaxial and triaxial) are systematically studied experimentally and theoretically. First of all, the dynamic fracture characteristics of granite materials and the strength and deformation characteristics of granite materials under uniaxial and triaxial dynamic compressive stress were studied experimentally. The results show that the dynamic fracture toughness of granite increases with the increase of loading rate and the decrease of loading time. In the uniaxial case, the compressive strength of granite increases with strain rate, Young’s modulus and Poisson’s ratio change little with the strain rate. In the triaxial case, the compressive strength of granite also increases with the increase of strain rate, and the increase of strength tends to decrease with the increase of confining pressure. Young’s modulus and Poisson’s ratio change little with the strain rate ; The compressive strength of granite increases with the increase of confining pressure and has the same trend at different strain rates. The Young’s modulus and Poisson’s ratio of granite increase slightly with the increase of confining pressure. Based on the experimental study, the sliding crack model is applied to study the mechanical properties of granite under compressive stress. In the uniaxial case, a series of slip-type cracks parallel to the axial stress are used to simulate the splitting failure modes of rock materials and to consider the interaction between the cracks. According to the dynamic propagation criterion of crack and energy balance theory, the theory of granite under different strain rates is obtained.