武汉地铁工程中沙漏型岩溶注浆新技术探讨及实践

Discussion and Application of New Grouting Technology in Hourglass-shapedKarst in Wuhan Metro Project

文章对武汉地区岩溶地面塌陷案例及各地区岩溶治理方案措施进行了统计和总结分析,说明了岩溶注浆的重要性。武汉地铁6号线红建路站及两端区间穿越长江一级阶地沙漏型岩溶地质结构,主要采用了岩层帷幕注浆和溶洞充填注浆等岩溶处理措施。但在施工中遇到了注浆成孔引起的砂颗粒漏失、钢套管无法拔出、浆液窜入砂层、注浆无法持压导致不能有效填充溶洞、浆液无法有效计量等一系列难题。为了解决这些问题,通过咨询论证、借鉴水利工程经验、前期试验研究等方式对传统岩溶注浆成孔工艺和流量监测工艺、浆液配比、终浆标准等进行优化。研究探索了一套"钢套管+内套PP-R管+钻杆基岩成孔+止浆塞+注浆流量记录仪"的岩溶注浆技术。岩溶注浆中分工序选择不同的浆液配比并探索采用适应于本工程地质特点的终浆标准。红建路站及两端区间岩溶处理工程实践验证了注浆新技术的适用性和有效性。

Statistics,summary and analysis are carried out in terms of karst ground collapse cases in Wuhan,karst treatment schemes and measures in various regions,with the aim of showing the importance of karst grouting.Hongjian Road Station and running tunnel sections at its both ends of Wuhan Metro Line 6 cross the hourglass-shaped karst geological structure in the first terrace of the Yangtze River,where such karst treatment measures as curtain grouting in rocks as well as grouting and filling in karst caves are adopted.However,a series of problems are encountered during the construction,e.g.sand particles leak due to drilling and grouting,steel casing could not be pulled out,grouts penetrate into the sand layer,grouting pressure could not be maintained so that karst caves could not be filled effectively,grouts could not be measured effectively,and so on.In order to solve these problems,the traditional karst grouting hole forming process,flow monitoring process,grout ratio and final grouting completion standard are optimized through consultation,demonstration and with reference to water conservancy construction experience and preliminary experimental study.A set of karst grouting technologies,e.g."steel casing+inner PP-R pipe+hole forming in rocks with drill rod+grout stop plug+grouting flow recorder",are studied and explored.In karst grouting,different grout ratios are selected in different periods,and the final grouting completion standard suitable for geological characteristics of the project is explored as well.The karst treatment practice at Hongjian Road Station and the running tunnel sections at its both ends verified the applicability and effectiveness of the new grouting technology.