注浆法在富水砂卵石地层城市轨道交通联络通道暗挖施工中的应用

Application of Grouting Method for Underground Excavation Construction of Urban Rail Transit Connecting Passage in Water-rich Sandy Cobble Stratum

[目的]成都地铁19号线二期工程九江北站—龙桥路站区间1#联络通道处于富水砂卵石地层,受周边建(构)筑物位置所限,不宜采用常规方法进行施工,为此需采用不降水法为该联络通道暗挖施工提供无水条件。[方法]根据1#联络通道的工程特点,在对比分析冻结法和顶管法等常规方案的基础上,采用注浆法为该联络通道暗挖提供无水条件。根据富水砂卵石地层的特点,同时受周边建(构)筑物布局的限制,19号线主线隧道内决定采用水平注浆法施工。详细阐述了1#联络通道注浆法施工方案,针对动水条件下砂卵石地层涌水、涌砂,成孔困难,串冒浆等难点,提出相应对策。从可靠性、造价、变形控制及运营维护等方面总结了水平注浆法的优势。[结果及结论]1#联络通道施工完成后,经测试检查孔每米出水量不大于0.13 L/min,达到预期止水要求,满足该联络通道暗挖的无水条件;开挖过程揭示,开挖面基本无渗水,1#联络通道安全贯通。

[Objective]Connecting Passage 1 in the interval of Jiujiang North Station and Longqiao Road Station of Chengdu Metro Line 19 Phase II is located in water-rich sandy cobble stratum.Limited by the location of the surrounding buildings(structures),it is not suitable to adopt conventional method for the construction.Therefore,the non-precipitation method is required to provide a water-free condition for the underground excavation construction of this connecting passage.[Method]According to the engineering characteristics of Connecting Passage 1,and based on a comparative analysis of conventional schemes such as freezing method and pipe-jacking method,the grouting method is adopted to provide a water-free condition for the underground excavation of this connecting passage.According to the characteristics of water-rich sandy cobble stratum and limited by the layout of the surrounding buildings(structures),it is decided to adopt the horizontal grouting method for Line 19 main line tunnel construction.The construction scheme of Connecting Passage 1 grouting method is elaborated in detail.In view of the difficulties such as water gushing and sand gushing in the sandy cobble stratum,hole forming difficulty,slurry leakage and spillover under dynamic water conditions,corresponding countermeasures are proposed.The advantages of the horizontal grouting method are summarized from the aspects of reliability,cost,deformation control,operation and maintenance.[Result&Conclusion]After completing the construction of Connecting Passage 1,water output per meter of the inspection hole is not more than 0.13 L/min after testing,achieving the expected water-stop requirement and meeting the water-free condition for the underground excavation of this passage.The excavation process shows that there is basically no water seepage on the excavation surface,and Connecting Passage 1 is safely connected.