复杂环境超浅埋大直径TBM始发施工技术研究

Construction technology for ultra shallow buried large diameter TBM starting drilling in complex environments

目前国内城市隧道尤其是3 km以上的大断面隧道施工中,TBM(全断面硬岩隧道掘进机)掘进法已经得到广泛应用,而随着城市轨道交通和城镇化的不断发展,TBM始发场地越来越受制约,因此TBM在浅埋地层条件下始发会越来越频繁。根据国内外盾构施工经验,大直径TBM始发端的隧道覆土埋深通常设计为3/5~4/5倍隧道直径,并采用水下始发、增加洞门长度等措施以规避TBM始发期间的施工风险,目前国内针对周边复杂环境条件下、始发埋深小于0.5倍隧道直径的大直径TBM始发案例较少。本文以重庆市轨道交通27号线西永站—磁器口区间小里程TBM区间为背景,介绍了大直径TBM在周边复杂环境下超浅埋始发的施工技术;通过对地表深层注浆、超前大管棚、超浅埋段反压回填等端头加固技术研究,并结合大纵坡控制、始发过程中姿态控制技术及信息化监测研究,得出超大直径TBM在覆土深度均小于0.5倍隧道洞径工况下顺利始发的技术参数及加固手段,对同类型工况条件下的TBM始发具有一定借鉴意义。

At present,TBM(Full Face Hard Rock Tunnel Boring Machine)has been widely used in the construction of urban tunnels,particularly for tunneling distance exceeding 3 km in China.However,with the continuous development of urban rail transit and urbanization,the starting site of TBM is becoming more and more restricted.Consequently,starting drilling under shallow burial conditions is becoming more frequent.Based on domestic and international shield tunneling experiences,the burial depth of the tunnel cover at the start of large-diameter TBM is usually designed to be 3/5-4/5 times of the tunnel diameter.Measures such as underwater starting and increasing the tunnel portal length are implemented to mitigate construction risks during the TBM starting drilling phase.However,currently there are relatively few cases of large-diameter TBM starting drilling in China under complex surrounding environmental conditions with an initial burial depth less than 0.5 times the tunnel diameter.This article took the small-mileage TBM section from Xiyong Station to Ciqikou on Chongqing Metro Line 27 as the background,and presented the construction technology for large-diameter TBM starting drilling from ultra-shallow burial in complex environments.Reinforcement technologies including deep surface grouting,advanced large pipe sheds,and ultra-shallow buried section backpressure backfilling,along with implementing extensive longitudinal slope control and attitude control technology during the initiation process,and information monitoring were investigated.The technical parameters and reinforcement methods necessary for the starting of ultra-large diameter TBM was presented,which can provide particular reference significance for TBM starting drilling under similar operational conditions.