岩溶地区地铁隧道盾构施工风险识别与评价研究

Identification and Evaluation on Shield Construction Risk of Metro Tunnel in Karst Area

贵阳市地铁3号线盾构施工区间岩体内存在多处溶孔、垂直溶洞和溶蚀破碎带,在这种复杂地质条件下,盾构施工工期长且施工技术复杂。采用可考虑多因素的层次分析法对岩溶地区地铁隧道盾构法施工风险进行研究:首先,根据工程现场资料及专家咨询意见建立岩溶隧道盾构法施工风险评价指标体系,包括盾构掘进风险、周边环境风险、自然及地质风险3个一级指标,盾构机选型与刀盘、刀具选型和盾构进出洞加固等13个二级指标和相应风险源;然后,利用层次分析法分别计算各个风险指标权重,并结合专家打分法对岩溶隧道盾构法施工风险进行综合风险指数计算;最后,根据计算得到的风险指数确定隧道施工风险等级,并给出相对应的风险控制措施。将该风险评价模型应用于贵阳市轨道交通3号线农学院站—花溪公园站区间盾构法施工中,得到总体风险等级为Ⅱ级,该结果与现场施工情况基本吻合,说明该模型具有较好的实用性。

The rock mass of the shield construction section of Guiyang metro line 3 is mainly composed of solution pores,vertical karst caves and dissolution fracture zones.The shield construction under such complex geological conditions has a long construction period and needs complex construction technology.The multifactor analytic hierarchy process was used to study the risk of shield construction of subway tunnel in karst area.Firstly,the risk evaluation index system of shield construction of karst tunnel was established according to the in-situ data and expert consultation,including 3 first-level indicators including shield tunneling risk,surrounding environmental risk,natural and geological risk,13 second-level indicators including shield machine type selection and cutter head,tool selection,and shield hole reinforcement and the corresponding risk sources.Secondly,the analytic hierarchy process was used to calculate the weight of each risk indexes,and the comprehensive risk index was calculated for the shield construction risk of karst tunnel combined with the expert scoring method.Finally,the construction risk level was determined according to the calculated risk index,and the corresponding risk control measures were given according to the risk acceptance criteria.The constructed risk assessment model was applied to the shield construction of Guiyang Metro Line 3 Nongxueyuan to Huaxi Park Stations,and the overall risk level wasⅡ.The results are in good agreement with the field construction,indicating that the model has good practicability.