【摘要】 针对卸荷裂纹发生的随机性,发生时间的滞后性特点,采用岩石断裂力学和流变力学,结合Monte-Carlo方法描述岩体裂纹的随机分布,研究随机卸荷裂纹扩展的时效特性,建立随机卸荷岩体裂纹流变断裂模型及数值方法,并提出卸荷岩体裂纹止裂判据。以最小应力σ3卸荷为例,探索不同卸荷条件下,随机卸荷裂纹的萌生、流变扩展规律。研究结果表明:随着最小应力σ3的卸荷,岩体裂纹瞬态扩展和流变扩展都增强;最小主应力接近0 MPa时,对最小主应力较小的扰动变化,将导致卸荷裂纹的成倍增加。卸荷岩体裂纹的流变断裂与岩石流变过程相似,呈现出衰减流变阶段和定常流变阶段2个阶段。随机卸荷岩体裂纹流变断裂模型合理地解释了岩体裂纹的延迟起裂、流变扩展和止裂,为研究卸荷岩体变形损伤特性提供了细观层面上的理论依据。更多还原

【Abstract】 According to the randomness of occurrence and the hysteretic nature of occurrence time of unloading cracks, the rock fracture mechanics and rheological mechanics were adopted to study the aging characteristics of random unloading cracks extension. Based on random distribution of rock cracks depicted by Monte-Carlo method, the rheological fracture model of random unloading rock mass cracks and numerical simulation were established, and criterion of unloading cracks arrest was also proposed. Taking unloading of the minimum principal stress as an example,the initiation and rheological extension laws of random unloading cracks were explored. The results show that the transient cracks extension and rheological cracks extension are strengthened because of unloading of the minimum principal stress. When the minimum principal stress is close to 0 MPa, small disturbance to the minimum principle stress will give rise to double increasing of unloading cracks. The rheological fracture process of unloading rock mass cracks is similar to that of rocks, and rheological fracture of rock cracks indicates attenuating rheological stage and steady rheological stage. The rheological fracture model of random unloading rock mass cracks reasonably explains the delay cracks initiation, rheological extension and cracks arrest of rock mass, which provides microscopic theory basis for deformation damage of unloading rock mass.更多还原