富水岩溶地铁深基坑注浆止水机理及效果评价

Analysis on groundwater cut-off mechanism and grouting effect of deep Metro excavation in water-rich karst area

富水岩溶地区城市地铁深基坑开挖过程中常面临涌突水防治、支护结构稳定性控制等技术难题,实施可靠的探测技术和有效的注浆手段是解决上述难题的关键。基于穿越富水岩溶区的贵阳地铁2号线延安路站深基坑涌水工程,采用区域水文地质调查、钻探、瑞雷波探测等技术手段分析了场地内岩溶发育特征;通过全断面注浆在基底下形成了一定厚度的注浆止水板;通过理论分析揭示了岩溶注浆止水机理。分析结果表明:注浆形成的结石块体起到了填充岩溶空隙、加固基底、封堵地下水的综合作用,注浆完成后,基坑施工工作面稳定,堵水效果显著。研究成果对富水岩溶地区地铁深基坑建设具有重要借鉴意义。

The technical problems such as water burst,stability of supporting structure are commonly encountered in the deep excavation of urban subway in water-rich karst zone. Reliable detection technique and effective grouting are the key to solving these problems. In order to prevent the groundwater burst in the deep excavation of Yan＇an Road Station in Guiyang Metro Line No. 2 located at high pressure waterrich area, the characteristics of karst development in the site were analyzed by means of regional hydrogeology study,drilling and Rayleigh wave detection etc. Groundwater cut-off layer is formed by whole section grouting at the bottom of the excavated pit. The mechanism of groundwater control by grouting was analyzed. The results show that the grout cemented soil plays in the act of karst gap filling,strengthening the pit bottom and sealing the groundwater. The excavation surface is stable and the water cut-off is successful on completion of grouting. The research results could be referred by the similar deep excavation projects in the water-rich karst area.