无端头加固条件下土压平衡盾构水下接收施工技术

为确保盾构在无端头加固条件下的富水砂层中安全接收，依托以色列特拉维夫红线轻轨工程，对采用竖井填水方法进行盾构水中接收的施工关键技术进行研究。主要研究与结论如下： 1）通过设置混凝土导台、洞门密封、螺旋密封、盾尾密封、盾构掘进参数控制、注浆控制等各项措施，保证了盾构在竖井中安全接收，提高了施工效率，节省了施工费用； 2）通过理论计算和实际验证，在竖井中注入高于地层水位约1 m的水，可防止地层中的砂被水从开挖间隙中带出； 3）合理的盾构密封控制可以防止涌水涌砂事故； 4）在竖井中设置双层混凝土导台，有利于调整盾构姿态以准确推上钢托架； 5）经过严密的施工组织设计，2台土压平衡盾构成功完成水下接收，竖井内无涌砂，地表沉降控制在规定值以内。

Construction Technology of Underwater Receiving of EPB Shield Under Condition of No end Reinforcement

The safe reception of shield in water rich sandy layer without end reinforcement should be guaranteed. Hence, the key construction technology of shield reception in water by means of filling water into the shaft is studied based on the Red Line Light Rail Project in Tel Aviv, Israel. Main studies and conclusions are as follows: (1) By carrying out measures i.e. concrete cradle, portal seal, screw seal, shield tail seal, shield tunneling parameter control, grouting control, etc., the shield is received safely in the shaft, the construction efficiency is improved and construction cost is reduced. (2) According to theoretical calculation and practical verification, the sand can be prevented from being taken out of the excavation gap by injecting water about 1 m above the groundwater level into the shaft. (3) Rational shield sealing control can avoid water gushing and sand gushing accidents. (4) The double layer concrete cradle in the shaft is conducive to shield attitude adjustment and smooth pushing on the steel cradle. (5) After rigorous construction organization and design, two EPB shields have successfully completed underwater reception; there was no sand gushing in the shaft, and the ground settlement was controlled within the prescribed value, which can provide reference for similar shield reception projects in the future.