基于离散单元法的裂隙岩体渗流与应力耦合作用机制研究

采用UDEC离散单元法中关于裂隙岩体开挖模拟及水力全耦合分析模型，分析裂隙岩体洞室开挖后，围岩应力与水力耦合作用导致的裂隙隙宽变化及渗流变化的过程。结果表明：洞室开挖完成后，在围岩渗流与应力耦合作用下，围岩中裂隙隙宽、裂隙中水压及其渗透流量的变化是一个动态过程，且相互作用与相互依赖；裂隙的闭合使得结构面水力梯度变大，作用在裂缝上的渗透压力增大，促进导水裂缝扩展，裂隙连通性增加；裂缝张开度增大，渗透能力增强，渗流量增大，其渗流压力相应降低；由于围岩中裂隙隙宽、压力和渗流量的动态依赖性，在一定条件下，裂隙隙宽的改变可导致局部水力通道的形成，高压水头从局部涌出，从而促进突水灾害的形成。研究成果初步表明了所采用方法的有效性，并为研究裂隙岩体中开挖洞室引起的突水问题提供了潜在的研究方向。

Study on Coupling Mechanism of Stress and Fluid Flow in Fractured Rock Mass Based on Discrete Element Method

The excavation simulation and fully-coupled model of the fractured rock in the discrete element method are used to analyze the changes in fracture aperture and the process of the flow change after excavation. The results show that the change of the fracture aperture, water pressure and fracture permeability of the fractured rock mass in the coupling conditions of the seepage and stress is a dynamic process, and also shows its interaction and interdependence. Owing to the closure of the fracture, the hydraulic gradient and the permeability pressure of the fracture turn large, and also promote the expansion of water cracks, and fissures connectivity increasing. The increase of the crack opening width will result in the increase of the infiltration capacity and seepage flow, and the reduction of seepage pressure. Because of the dynamic dependence of the fracture aperture, pressure and seepage, under certain conditions, changes in fracture aperture can lead to the formation of local water-passage, and the local emission of high pressure water, and thus promotes the formation of the sudden outgush disasters. Preliminary research shows the effectiveness of the method employed, and provides a potential research direction to study the sudden blowing in the excavation of fractured rock masses.