Experimental study on seepage characteristics and permeability of fractured rock mass in goaf

Abstract

In order to obtain the flow behavior of the mining-induced fractured rock mass, and to confirm the values of hydraulic conductivity of the fractured rock, which could provide a reference for mining impact assessment, two methods that the similarity material model experiment and seepage experiment were adopted in the study, and then, the fracture developmental state and distribution characteristics have been studied. From this, the study on seepage characteristic and the permeability of fractured rock mass with various fracture ratios in gob were conducted. The experiment and research results show that the groundwater flow with high-speed in the fractured strata presents nonlinear characteristics, and the flow regime and the permeability of fractured rock are obviously affected by the fracture rate of permeable media. In general, the permeability of fractured rock mass increases with the growth of the fracture ratio, and the permeability can be divided into two sections: the slowly increasing section and the dramatic increasing section. The vertical hydraulic conductivity of mining-induced fractured rock mass is between 0.067 cm/s and 0.649 cm/s, and the horizontal hydraulic conductivity is between 0.744 cm/s and 6.847 cm/s. The hydraulic conductivity of fractured rock mass is 2 to 4 orders of magnitude larger than that before coal mining.

Keywords

• coal mine mining
• fractured rock mass
• horizontal permeability conductivity
• vertical permeability conductivity
• non-darcy flow
• permeability test