Experimental And Numerical Study On Seepage Mechanism Of Rock Failure

Rocks are homogenous geological materials which contain natural weaknesses of various scales, such as micro-cracks, pores and lots of joints. Their existing provides convenient space for underground water reserving and moving. The seepage of underground water acts on rock mass by water pressure, which affects the stress distribution of rock mass and meanwhile the change of stress vector will induce the deformation of cracks, affecting their permeability, so the flow vector will be changed. This is so-called hydraulic-stress coupling.Instability of lots of rock mass engineering relates to underground water, for example, instability of dams, water outburst from seam floor and so on. The essential reason of their instability is that under the influence of hydraulic-stress coupling, native cracks in rock mass and that induced by engineering disturbance will initiate, propagate and coalesce, which leads to the instability of engineering.In order to study the characteristic of permeability in rock distortion and failure process. The relationship between permeability, peak strength and volume strain is studied by making sandstone and tuff samples and testing their mechanical parameters under triaxial environment, the results of experiment are read-in the software RFPA-Flow, the use of numerical means to supplement and comparative analysis of different pore pressure to undermine the impact of rock flow.First of all, The influence of osmotic pressure on the rock samples'permeability is obvious in the course of seepage, on the peak before and after the peak osmotic pressure difference increases over time showed negative exponential relationship,and the relation between volume strain and permeability through experimental study. The process of axial loading, the volume strain reflected the process of the evolution of permeability under the process of rock yield, weaken and failure, especially after the peak stress damage to the rock permeability effect Throughout the course of the failure of rock samples, acoustic emission activities with the stress changing showed different characteristics. Secondly, more system of study on the law of seepage failure under different osmotic pressure conditions through simulation calculation. The difference of distributions of hydraulic pressure and hydraulic gradient during rock failure between steady and unsteady seepage conditions is comparatively investigated. Under steady seepage condition, the permeability coefficient continuously increased during rock failure process. But under unsteady seepage condition, the time of pressure difference reached stability is shorted.Finally, the law and understanding which obtained from experimental and simulation calculation are applied to simulate the process of surrounding rock failure induced by mining under deep fault in the Hongtoushan. The results and the actual situation are basically the same, and providing the scientific basis for developing roadway seepage control.