Numerical analysis of the possibility of noxious gases infiltration into a shelter located in a gas-bearing coal-rock mass

Abstract

Shelters in coal mines are used to protect miners during accidents associated with gassing of roadways, fires, explosions of methane-air mixture. Supporting of the shelter must provide the necessary level of tightness to prevent the penetration of noxious gases from the mine atmosphere or gas-bearing rocks. The purpose of this work is to study the possibility of noxious gases penetration into a shelter in case of its sealing failure for the early detection of weak constructional elements and to ensure safe conditions for people in the shelter during accidents. To achieve the goal, methods of numerical simulation of time-dependent processes of elastic-plastic deformation and gas filtration were used. A coal-rock mass with a roadway and an adjacent shelter with typical supporting elements were considered at a depth of 400 m and 1000 m. The study of the stress state of the shelter support showed that under the considered conditions, in the case of a relatively small depth, hard steel and concrete constructional elements withstand the load without loss of their stability. With an increase in the depth of the shelter location, inelastic deformation of the concrete barrier between the shelter and the roadway occurs on a small area. The probable destruction of this zone will not lead to a violation of the entire barrier integrity, which makes it impossible to start mass exchange processes between clean air in the shelter and harmful combustion products in the roadway. The roof and walls of the shelter, covered with reinforced concrete and sealed, remain practically impermeable from the next day after their construction in both the first and second cases. But later, in the lower left corner of the shelter at a depth of 1000 m, methane from the coal seam begins infiltrating through the unsupported and unsealed floor. The developed numerical model can be used with other basic data on mining and geological conditions to identify constructional elements of a shelter, which lose stability during operation and threaten the shelter's tightness. Timely strengthening of such weak elements will prevent the danger of noxious gases infiltrating into the shelter. Keywords: time-dependent rock deformation, shelter, sealing failure, gas filtration, numerical simulation.