关键词: 浅覆土, 强透水砂卵石地层, 大直径盾构, 干接收, 泥水盾构, 掘进参数控制, 端头加固

Abstract: In order to solve the problems of receiving largediameter slurry shield in strong permeable sand pebble stratum with shallow overburden, based on large diameter slurry shield tunnel of Yuanjiang  in Changde City, dry receiving construction technology is proposed. The stability of the whole structure in end reinforcement area is improved and the conditions for shield acceptance are satisfied by using the joint reinforcement methods of RJP superhigh pressure jet grouting, vertical freezing and plastic concrete diaphragm wall in the end reinforcement area. In the process of shield dry receiving, by controlling various construction parameters and grasping the key points of construction timing accurately, shield machine smoothly passes through the existing pipeline and reinforcement area, and the maximum settlement of the pipeline and the surface is controlled within 6 mm and 5 mm respectively so as to ensure the accurate exit of the shield machine. In addition, portal brushes are installed in the steel ring of the portal to prevent soil loss when shield machine exits the tunnel. Meanwhile, synchronous grouting volume is increased and segments are connected and fixed with channel steel to ensure shield tail and support safety during the process of shield machine leaving the tunnel.

Key words: shallow overburden soil, strong permeable sand pebble stratum, large diameter shield, dry receiving, slurry shield, control of tunneling parameters, end reinforcement