济南地铁深基坑承压水控制技术研究

Study on confined groundwater control technique in deep excavation in Jinan Metro project

济南地铁R3线裴家营站位于济南白泉泉域附近,地下水丰富,基坑周边黏性土层受岩溶水顶托形成透水通道,室内外渗透试验结果差异较大,测试综合渗透性接近砂层,且原位声纳测试显示水平向渗透系数大于竖向渗透系数。基坑采用地连墙围护结构,通过数值计算确定利用地连墙下加深素墙作为基坑止水帷幕阻挡水平向补给。基坑底部碎石层受下部岩溶水向上顶托,具有承压性,对比确定采用减压与疏干联合降水方案。现场反馈该方案合理可行,基坑已顺利完成并回填。

Peijiaying Station of Jinan Metro Line R3 is located near Baiquan spring area with abundant groundwater. The cohesive soil in this area is supported by the underneath karst water to form a permeable channel,therefore the results of indoor and in-situ permeability tests of cohesive soil are different. The outdoor permeability test indicates that the permeability of cohesive soil is approximate to sand,and the horizontal permeability coefficient is greater than vertical permeability coefficient in situ sonar test. The excavation is retained by diaphragm wall. The numerical calculation shows that the diaphragm wall should be constructed further with non-reinforced concrete to cutoff groundwater. The gravel layer with confined water at the bottom of the excavation pit is caused by the karst water in limestone. The combination of relief and discharge method was recommended through comparative analyses. The site feedback shows that the scheme is reasonable and feasible,and the foundation pit has beeh successfully completed and backfilled.