Study On External Water Pressure Of Deep-lining Tunnel

Numerous deep lying tunnels are adopted with the water project construction transferring to the south-west area of China, the high external water pressure and flow are the most important problems faced in the tunnel design and construction. In order to calculate the high external water pressure, the rock seepage field and external water pressure coefficient should be treated in detail. Concentrated on the questions of high external water pressure and flow of the deep-lying tunnel, the basic theory and method calculating external water pressure are systematically studied, the high external water pressure of Jinping cascade 2 hydropower station is analyzed and studied in detail. The main contents are as follows:(1) Based on the fundamental seepage theory, the all-around effect of water table by rain infiltration are discussed with the equivalent infiltration intensity method.(2) The method of finite element discrete and optimal parameter back analysis is adopted.(3) Concentrated on the question of high external water pressure of the deep-lying tunnel, the basic theory and method calculating external water pressure are systematically studied.(4) Based on Jinping cascade 2 hydropower station, numerical simulation rain infiltration of seepage field under different drainage pattern and grouting pattern are studied, also, the high external water pressure is analyzed and studied and some seepage control measures are put forward.