天津地铁盾构施工对地表沉降影响的风险评估及精细化控制研究

Study on Risk Assessment and Fined Control of Influence of Shield Tunneling on Ground Surface Settlement: A Case Study on Tianjin Metro

目前我国城市地铁建设中对地表变形的要求愈加严格,仅依靠工程经验已很难实现。结合天津地铁天津站—建国道站盾构区间试验段的现场监测结果,对掘进过程中盾壳摩擦力、刀盘扭矩、掌子面压力和注浆压力等盾构掘进参数对地表沉降影响进行参数化模拟分析,并针对盾构掘进参数的波动造成的地表沉降计算结果进行风险损失等级的可拓法风险评估,基于风险损失评估结果以及盾构掘进参数实测结果进行统计分析得到风险失效概率,从而计算出各致险因子的风险值并提出相应的精细化控制措施。结果表明:1)该隧道试验段致险因子按风险值从大到小依次为盾壳摩擦力、注浆压力、掌子面压力、刀盘扭矩;2)在该区间后续下穿高速铁路的盾构掘进过程中,针对风险值较大的盾壳摩擦力、注浆压力波动制定精细化的风险控制措施,最终使地表沉降稳定在5.1 mm,满足了铁路运营的要求。

The requirements on ground surface deformation in the construction of Metro in urban areas are strict. The influence of shield boring parameters of Tianjin Station Station-Jianguodao Station section of Tianjin Metro,such as shield friction, cutterhead torque, working face pressure and grouting pressure, on ground surface settlement is numerically simulated. The risk assessment based on extension method is made on risk failure grade of calculation results of ground surface settlement under different shield boring parameters. The risk failure rate is obtained based on analyzing on the assessment results of risk failure and measured data of shield boring parameters; and then the risk value of every risk factor is calculated and relative fined control technology is proposed. The results show that： 1） The order of risk factors of the test section based on value-at-risk are shield friction,grouting pressure,working face pressure and cutterhead torque. 2） The final ground surface settlement of 5. 1 mm can meet the requirements by using fined control technologies.