成贵铁路上高山隧道超大型溶洞处理技术与应用

Treatment technology for super large karst cave in Shanggaoshan tunnel of Chengdu-Guiyang Railway and its application

隧道施工遇超大型溶洞,需对其进行科学地分析,查明其工程特性、分析评价其稳定性,进而制定安全、可靠、合理的工程处理措施。成贵铁路上高山隧道在施工过程中揭示出115 m×90 m×20 m(长×宽×高)的超大型溶洞大厅,底部岩溶堆积物厚30~49 m,隧道穿越长度约80 m。现场通过补充测绘、地质调查、钻探及内业分析对该超大型溶洞进行了详细的补充地质勘察。综合分析得出:岩溶大厅顶板大部分区域稳定性差,侧壁稳定性较差,但隧底堆积体整体是稳定的,经综合比选,采用填充混凝土的方法对溶洞大厅顶板及侧壁进行稳定处理;钻探查明溶洞底部堆积体最深可至隧底以下约49 m,层间夹有粗圆砾,且溶洞内揭示有稳定的地下水位,因此底部堆积体存在颗粒物质流失的隐患,研究后决定隧底采用桩板结构形式。经现场实施,各项工程措施合理可行、整治效果良好,保证了成贵铁路于2019年12月的顺利通车。

In case of super large karst cave in tunnel construction,it is necessary to scientifically find out its engineering characteristics,analyze and evaluate its stability,and then formulate a safe,reliable and reasonable engineering treatment plan.During construction of the Shanggaoshan Tunnel of Chengdu-Guiyang Railway,a great karst cave hall with a length,width and height of 115 m×90 m×20 m was revealed,the karst deposit at the bottom was 30~49 m thick,and the tunnel crossing length was about 80 m.Through supplementary mapping,geological survey,drilling and in-house analysis,it was concluded that the stability of most areas of the roof and side wall of the karst hall were poor,but the cavern accumulation body was overall stable.It was suggested that the roof and side wall of the cave hall be treated with full filled concrete.Through drilling,up-to 49 depth of deposit was found at the bottom of the cave,where some thick gravel layer was mixed,and there was a stable groundwater level in the cave,so there was a hidden danger of the loss of particulate matter in the bottom accumulations.It was suggested that the tunnel bottom be crossed in the form of pile plate.Through the in-situ implementation,the engineering measures were reasonable and feasible,and the renovation effect was good,which ensured the successful opening of Chengdu-Guiyang Railway in December 2019.