软土地层盾构下穿铁路枢纽沉降规律及施工控制

The settlement law and construction control of railway hub traversed by a shield tunnel in soft ground

嘉兴市域外配水工程(杭州方向)输水盾构隧道长距离下穿乔司编组站出发场11股道、杭州北车辆段17股道及道岔区和沪昆铁路上行线2股道,其地层和工程建筑环境复杂,对变形控制要求极高。本研究以此案例为背景,采用现场实测与有限元模拟相结合的方法,探讨了盾构下穿大型铁路枢纽过程中铁路变形规律及安全控制措施。结果表明:软土地层深埋隧道采用摩尔-库伦模型计算出的道床沉降与监测结果一致性较好,建议穿越道岔区隧道埋深不小于35 m;盾构下穿既有线道床顶面最大沉降与地层损失呈线性关系,建议穿越道岔区地层损失率不大于0.3%。

Jiaxing City′s extraterritorial water distribution project(Hangzhou direction)long-distance shield tunneling underneath 2 roads of the Shanghai-Kunming railway Upstream Line,17 roads and turnout area of Hangzhou North Depot,11 roads of Departure Yard of Qiaosi Marshalling Stationas section road Interchange project.The stratum and engineering building environment are complex,and the deformation control requirements are very high.Based on this case,the method of field test and finite element simulation were used to discusse the railway deformation law and safety control measures in the process of shield tunneling through large railway hub.The results indicated that the numerical model results matched the monitoring data well,which calculated by Mohr-Coulomb model for deep buried tunnels in soft soil layer.It was recommended that the buried depth of the tunnel should not be less than 35 m when the shield passed through the turnout area;the analysis on the relationship between different loss ration and the maximum settlement of subsidence bed traversed by a shield tunnel revealed that the maximum settlement of the subsidence bed had a linear relationship with the formation loss.The recommended loss ratio of a shield tunnel passing through the turnout area should be no more than 0.3%.