Construction Techniques in Crossing Water-rich Sand Stratum of Deep Buried Large Tunnels

摘要

As a subdivision and backbone project of engineering of drawing water from Datong River into Huanshui River, the water transfer for main channel project is designed to transfer water from Datong River to Huangshui River, with the total amount of 3.6×108m~3 in a short-term and 7.5×108m~3 in a long-term. The project scale is large II. It is determined to be 2-level for main structure, 3-level for secondary structure and 4-level for temporary structure. The diversion tunnel, which is a non-pressure tunnel to draw water, is 24165.83m in length. The ground elevation of tunnel axis is 2943～4020m, the maximum and mean burial depths are 1100m and about 480m respectively, so that it is a deep and long tunnel, which is constructed with TBM, with 5m for diameter, 2955.6 and 2941.7 respectively for elevation of inlet floor and outlet floor. The designed flow of water diversion is 35m~3/s, longitudinal slope is i=0.00054529, and the maximum flow velocity within the tunnel is 2.24 m/s.