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岩质边坡在开挖过程中会引起内部的缺陷不断劣化,以致在部分区域形成贯通,进而发展成宏观裂缝导致边坡失稳。将边坡的开挖过程等效为在开挖面施加等效荷载并逐渐减小至0的过程。在此等效开挖的过程中,坡面一定范围内的裂隙会处于拉剪应力状态,以连续介质力学为基础,结合损伤力学以及断裂力学,推导出裂隙在受拉剪应力状态下的损伤演化本构模型。利用宏观的体积模量反映岩体的损伤程度,并定义破坏度用以表征实际岩体内部的破坏情况,在FLAC3D中开发并实现裂隙岩体卸荷损伤模型的计算。以广西凤山石灰岩建材矿山为例,计算并分析考虑及不考虑卸荷损伤2种工况的位移值及塑性区,证明该模型的正确性以及能更准确地反映坡体内部的真实情况。对比分析开挖卸荷后岩体的损伤度及破坏度后发现,以破坏度反应岩体的损伤情况,可以更加直观和准确地确定岩体的稳定状态。
In the process of excavation, the rock slope will cause the internal defects to deteriorate continuously, which leads to the formation of penetration in some areas and further to macro-cracks which lead to the instability of the slope. The slope excavation process is equivalent to the equivalent load applied to the excavation face and gradually reduced to zero. During this equivalent excavation, the cracks within a certain range of the slope will be in the state of tensile shear stress. Based on the continuum mechanics, combined with the damage mechanics and the fracture mechanics, the damage of the fractures under tensile stress is deduced Evolutionary constitutive model. The macroscopic bulk modulus is used to reflect the degree of rock mass damage and the degree of damage is defined to characterize the internal rock failure. FLAC3D is developed to calculate the unloading damage model of rock mass. Taking the Fengshan limestone building material mine in Guangxi as an example, the displacement values and plastic zones with and without consideration of unloading damage were calculated and analyzed, and the correctness of the model and the real situation inside the slope body can be more accurately reflected. By comparing the damage degree and failure degree of rock mass after excavation, it is found that the rock mass stability can be determined more intuitively and accurately by the damage degree of rock mass with destructive degree.