岩溶地区双连拱隧道超前地质预报及施工技术研究

岩溶地区修建双连拱隧道难度较大，岩溶探测、支护方式选择等成为施工的关键问题。依托广西宜河高速公路某连拱隧道，根据围岩等级分别制定Ⅲ级、Ⅴ级围岩施工和支护方案，施工期间采用超前地质雷达探测隧道掌子面前方未开挖岩体，通过分析雷达反射波波形图，预测隧道中导洞存在4处溶洞，隧道开挖过程中揭露了3处溶洞，与地质雷达探测结果基本一致，证明了超前地质雷达的可靠性和重要性。针对溶洞地段采用Ⅴ级岩体支护方案，即采用套拱进行溶腔的加固处理，监测数据显示其变形基本值为0，表明该加固处理方法的可靠性。

Study on Geological Prediction of Twin-arc Tunnelsand Construction Technique in Karst Areas

It is difficult to build a double arch tunnel in Karst areas. The key problems in the construction are karst exploration and support method selection. If not found and properly handled in time, these problems may result in serious consequences. Relying on the tunnel of Yihe Express in Guangxi, construction and supporting under class III and class V are respectively formulated according to the grade of surrounding rock. During construction, the geological radar is used to detect the unexcavated tunnel; four karst caves are predicted in tunnel through the analysis of radar reflected wave. During the excavation of the tunnel, three karst caves are revealed, which are essentially consistent with the detection results of the geological radar. Hence, the reliability and importance of the advanced geological radar are proved. Rock supporting of class V is adopted in the karst cave, that is, using the sleeve arch to reinforce the cavity. According to the monitoring data, the basic deformation value is 0, which indicates the reliability of the strengthening method. These results can serve as a reference for the excavation and construction of double arch tunnels under similar geological conditions.