Study On The Seepage Mechanism Of Surrounding Clastic Rock In Hydrothermal Deposit

Forecasting of mine drainage is the basis for design of mining drainage scheme, and is directly related to mine safety production. In the process of mining, mining often has a great effect on the fracture development of tunnel surrounding rock, leading to changes of seepage conditions and mine drainage.Based on this point, we take the clastic rock of a hydrothermal deposit (from Anhui province) as an example, after detail analysis of the mine drainage and the change of the press which induce the fracture development of tunnel surrounding rock). We made the rock into 6 groups which collected from the design gallery. Using 6 set of samples do triaxial mechanics test under condition that the confining pressure changes from 5 Mpa to 10 Mpa and the osmotic pressure changes from 1 Mpa to 4 Mpa. The paper discusses fracture development process and degree caused by unloading during the mining. The result of study shows as follow. At first, with the increase of confining pressure, the coefficient of permeability of each deformation stage decreases, but after destruction, coefficient of permeability improves 1-2 order of magnitude for each. Secondly, combining with the established physical model, we know the limit of the hydraulic gradient when the seepage condition changes and its relating influencing factors, and that the scope when seepage change obviously is mainly concentrated near the wall rock, the value of limit hydraulic gradient is about permeability ratio of surrounding rock before and after the destruction and displacement related. At last, indirect coupling method is used to establish a numerical model couple the stress field with seepage field in the case of study, thus indicating the change of seepage condition and its impact on mine drainage. Anyway, without considering the unloading effect’s impact on the fracture rate, the normal mine drainage based on the traditional numerical process is larger than that considering change of seepage condition. In this case of study, it is 48% larger.The results above can provide a theoretical basis for reference which is much closer to the actual value of forecasting water drainage, design of mine drainage scheme, comprehensive utilization of mine drainage resources and water environmental protection.