Study on fracture and seepage characteristics of rock mass with high water pressure caused by unloading

¹ College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China ;
² State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology，Shandong University of Science and Technology，Qingdao 266590, China

^* Corresponding author: skdrcb@sdust.edu.cn

Abstract

Research on the damage and seepage characteristics of unloading rock with high water pressure can help to further understand the mechanism of water inrush in deep mine and to take effective measures to prevent water inrush. In this paper, the finite element software RFPA2D-Flow was used to study the failure and seepage characteristics of unloading rock coupled with high water pressure and high stress. The effects of different water pressure on the failure of unloading rock and the law of seepage were investigated. The results show that the form of unloading rock failure without water pressure is brittle; however, the failure form of unloading rock with water pressure is obviously ductile failure, and the fracture is mainly concentrated at the bottom of the rock sample with high water pressure. During unloading, the seepage coefficient of rock increased with the increase of unloading amount until sudden jump occurs, and the failure form and permeability law of the rock with different water pressure were basically the same, but the larger the water pressure difference, the smaller the effective unloading capacity is needed when the permeability coefficient suddenly jumps, this shows that the larger the water pressure difference is, the more likely the rock mass will be damaged by water inrush under unloading condition.