高速铁路浅埋暗挖隧道近距离上穿既有地铁隧道风险控制研究

Risk Control Study of Shallow Buried Tunnel Upper Crossing Existing Tunnel at Short Distance

新建京张高铁清华园隧道近距离上跨既有北京地铁15号线,新建隧道上覆土层厚5 m,两隧道相距仅0.8 m。超薄的夹土层厚度无疑会加大新建隧道的施工难度,稍有不慎将会对下卧隧道造成严重损害,影响其正常运营。以该工程为背景,根据工程特点和地层条件,在施工过程中采用双侧壁导洞开挖、地表注浆加固、掌子面注浆加固、两隧道间施加锚索加固周围土层等风险控制方法,通过自动化监测进行数据信息获取并反馈指导下一步施工。现场测量数据显示,采取相应措施后,地表沉降最大值为7 mm,下卧隧道上浮隆起最大值仅4.8 mm,这些风险控制措施既降低了施工风险,保证了人员安全;又可有效减少地表沉降和下卧隧道的隆起,保证既有隧道的正常运营。

The newly-built Tsinghuayuan Tunnel of Beijing-Zhangjiakou High-speed Railway runs vertically through the existing tunnel Beijing metro line 15 with short distance.Overlying soil thickness of the newly-built tunnel is 5 m,and there is only about 0.8 m distance between the two tunnels.It is obviously that such a thin layer will make it harder to build the new tunnel,it will take serious destroy to the underlying tunnel and affect its normal operation by a slight error.Based on the project and according to the engineering characteristics and stratum conditions,a series of risk control methods such as adopting both side drift method excavating,ground grouting reinforcement,palm surface grouting reinforcement,and anchoring cable reinforcement for the soil layer between the two tunnels were adopted during construction.At the same time,data information was provided to guide the next construction through the automated monitoring.The field measurement data shows that the maximum surface settlement is only 7 mm and the maximum floating uplift value of the existing tunnel is only 4.8 mm by taking corresponding measures.These risk control methods not only reduce the construction risk and ensure the safety of personnel;but effectively reduce the surface settlement and the floating uplift value of the existing tunnel which help ensure the normal operation of the existing tunnel.