超浅埋暗挖大跨隧道下穿既有隧道的沉降控制技术

文章基于成都博览城综合交通枢纽18号线西博城站超浅埋暗挖大跨隧道施工实例,针对原设计CRD法施工存在的不足,提出了超浅埋暗挖大跨隧道下穿既有隧道的沉降控制和CRD法施工优化技术方案,并在施工中采用旋喷桩、超前大管棚和超前小导管注浆等辅助措施进行地层加固,优化CRD小分部台阶开挖法及衬砌分部分块施工方案。实践证明,采用优化的CRD法施工方案和措施是有效的,减少了安全风险、加快了施工进度、降低了工程成本,可为今后类似工况条件下地铁区间暗挖大跨隧道下穿既有城市道路、隧道的施工和地表沉降控制提供借鉴。

Settlement Control Techniques of the Super-shallow Buried Large-span Mined Tunnel underneath an Existing Tunnel

Taking the super-shallow buried mined tunnel with large span at the Xibocheng station of Chengdu met⁃ro line 18 as an example,aiming at the deficiencies of original design of CRD method,a technical scheme for settle⁃ment control and optimization of CRD construction of the super-shallow buried large-span mined tunnel underneath an existing tunnel is proposed,the auxiliary measures of jet grouting pile,advance large pipe-roof and condulet grouting are adopted to reinforce stratum,and the small-section bench method of CRD and partitioning lining con⁃struction schemes are optimized.The practice shows that the optimized CRD construction method and measures are effective,decreasing the safety risks and speeding up the construction speed and reducing construction cost.