Numerical study on the influence of heat-flow coupling direction on the temperature of double-fractured rock mass

The influence of heat-flow coupling direction on the temperature of the fractured rock mass is directly related to the safety of nuclear waste disposal project. There are less documents on the heat-flow coupling in different direction compared to these in the same direction. Based on the conceptual model of heat-flow coupling for fractured rocks, the effects of fracture water flow in the same direction, opposite, and perpendicular directions on the rock temperature field, the fracture plane temperature field, and the outlet water temperature are computationally analyzed by using the discrete element program. The results reveal that: The combined effect of heatflow coupling in the same (perpendicular) direction between the two fractures (F1 and F2) increases the temperature in the downstream region of the water flow and decreases the average temperature of the rock mass between the two fractures, which is conducive to the heat dissipation around the waste tank. The combined action of heat-flow coupling in the opposite direction in the F1 and F2 raises the rock mass temperature of in the downstream region of the water flow in each fracture and the average temperature of the between the two fractures. The heat superposition effect occurs near the waste tank, which is not conducive to heat transfer near the waste tank. The closer the temperature observation point is to the fracture, the stronger the heat absorption and cooling effect of the water flow is, which lowers the temperature at the observation point.