Seepage analysis of Chuanqin diversion tunnel under the condition of deep well dewatering

Abstract

Dewatering in deep wells would lead to the decline of groundwater level, which would reduce the strength and stability of the soil and affect the construction safety of the diversion tunnel. To study the influence of deep well dewatering on the seepage field of the tunnel during the construction period, a three-dimensional seepage finite element model of the Chuanqin Tunnel of Xixiayuan water control project and irrigation area project was established. The construction plan of the tunnel and the change of Qinhe water level were considered to analyze the seepage characteristics of the tunnel under the conditions of deep well dewatering and without dewatering. The results show that the dewatering of the deep wells affects the tunnel excavation, changes the potential distribution characteristics of the seepage field around the deep well, and forms a falling funnel on the infiltration surface. The water level contour is in a backwater ring near the deep wells. Compared with the deep well without precipitation, the maximum seepage gradient and unit width seepage flow of deep well precipitation are increased by 18.6 times and 3.3 times, respectively, and the seepage stability of the soil layer under all conditions meets the requirements. The research results can provide a basis for the design and construction of similar water diversion tunnels.