Thermal environment improvement of underground mine tunneling face using enhanced geothermal system technology

Abstract

To solve the problem of high-temperature thermal damages to the mine underground driving working face of a dry-hot-rock-enriched area, an active cooling method for fracturing water injection of the surrounding rock of the deep mine is proposed based on analysis of the heat dissipation mechanism of the surrounding rock. An artificial thermal reservoir is formed in the high-temperature rock mass around the tunneling roadway by stimulation, such as a high-pressure crack, and the heat energy of the surrounding rock is extracted by heat exchange of the heat-carrying fluid and the high-temperature rocks mass to reduce the ambient temperature of the roadway. The design of a down hole water injection cooling system based on enhanced geothermal system (EGS) technology is presented and a simplified EGS heats collection model is used for fluid-enclosure. Numerical simulation of the temperature field of the rock coupling shows that the temperature of the surrounding rock can be effectively reduced by increasing the water injection speed and fracture porosity, and improvement of the underground thermal environment can improve the working efficiency. For a water injection rate of 14m/s and porosity of0.18, the average cross section temperature was 41.95?C, which is nearly 5?C lower than the original rock temperature of 46.85?C.