Abstract:The length of the counter-slope drainage in the drilling and blasting section of a water conveyance tunnel is 3 410 m, crossing the multiple water-rich fault fracture zones and soluble rocks. The total length of its inclined shaft branch tunnel is 1 872 m and a height difference is 167.4 m. The risk of sudden water inflow in the tunnel is extremely high. It is predicted that the maximum stable sudden water inflow is 30 000 m3/d, and the maximum single-point sudden water inflow at the fault zone increases by 20 000 m3/d. The two-stage counter-slope relay drainage system of "three-level branch tunnel + two-level main tunnel fixed pumping station" is determined through the determination of water inflow, comparison of the level number and location of branch tunnel / main tunnel pumping stations, and type selection of water pumps. The configuration of drainage pipeline is calculated. A quick switching device is used as the emergency drainage pipeline for the high-pressure air duct. The intelligent control system is applied to strengthen the drainage operation management, which realizes the goals of cost saving, energy consumption reduction and risk prevention, and solves the problems of drainage and water inflow prevention in long-distance high counter-slope tunnels, providing the important guarantees for the safe and efficient construction of long-distance complex geological water-rich tunnels, and experiential reference and inspiration for similar projects.
