软弱地层超大矩形顶管盾构隧道近接施工加固方案优选研究

A Study on Optimization of Reinforcement Scheme for Adjacent Construction of Super-large Rectangular Pipe Jacking Shield Tunnel in Soft Ground

为保证软弱地层中超大矩形顶管盾构隧道近接施工安全,以某矩形顶管盾构隧道近接下穿既有高速铁路为工程背景,研究超大矩形顶管盾构隧道近接下穿高铁段不同施工加固方案的效果。结果表明:采用超前注浆可使开挖面主动失稳位移减小25.64%,被动失稳位移减小17.65%,轨道沉降减小30.38%。采用人工挖孔桩+D型钢便梁可使开挖面主动失稳位移减小51.28%,被动失稳位移减小29.41%,轨道沉降减小42.31%;现场监测表明,采用人工挖孔桩+D型钢便梁加固后轨道沉降最大值仅为1.65 mm,超大矩形顶管盾构隧道成功下穿既有高速铁路,人工挖孔桩+D型钢便梁保证了超大矩形顶管盾构隧道近接施工安全和高速铁路正常运营。

In order to ensure the safety of the adjacent construction of the super-large rectangular pipe jacking shield tunnel in the soft ground,taking a rectangular pipe jacking shield tunnel adjacently passing under the exist⁃ing high-speed railway as a study case,the effects of different construction and reinforcement schemes of the superlarge rectangular pipe jacking shield tunnel adjacent to the high-speed railway section are studied.The results show that when advanced grouting is adopted,the active instability displacement can be reduced by 25.64%,the passive instability displacement can be reduced by 17.65%,and the track settlement can be reduced by 30.38%for the ex⁃cavation face.And when the manually excavated pile+D-shaped steel auxiliary beam are adopted,the active insta⁃bility displacement can be reduced by 51.28%,the passive instability displacement can be reduced by 29.41%,and the track settlement can be reduced by 42.31%for the excavation face.Field monitoring shows that the maximum settlement of the track after reinforcement by the manually excavated pile+D-shaped steel auxiliary beam is only 1.65 mm.The super-large rectangular pipe jacking shield tunnel has successfully passed under the existing highspeed railway.The manually excavated pile+D-shaped steel auxiliary beam ensure the adjacent construction safety of the super-large rectangular pipe jacking shield tunnel and the normal operation of the high-speed railway.