上软下硬富水复合地层水泥砂浆护壁保压换刀技术应用

Cement Mortar Retaining Wall Pressure Maintaining Knife Change Technology Under Upper Soft and Lower Hard and Water-rich Composite Strata

南京地铁3号线新庄站—鸡鸣寺站区间穿越玄武湖,盾构机所处湖底地层以粉质黏土、粉质黏土夹卵砾石、强风化角岩化泥岩为主,该地层上软下硬、自稳性差、透水性强,盾构开舱风险高。通过盾构造型及刀盘配置,合理选择开舱位置,通过分析换刀风险,决定采用水泥砂浆护壁技术进行保压换刀施工,并详细介绍水泥砂浆护壁技术对掌子面土体稳定性、气密性的改善,解决上软下硬富水复合地层条件下安全换刀的问题。

Nanjing subway line 3Xinzhuang station to Jimingsi station across Xuanwu lake,the strata are dominated by silty clay,silty clay with egg gravel,strong weathering angle rock mudstone at the bottom of the lake,this strata is soft and hard,with poor self-stability and strong permeability,there is a high risk of shield construction.By reasonable selection of shield and cutter configuration,choose open position, analyzes tool change risk,it decides to adopt the cement mortar wall technology pressure maintaining knife changer,in this paper,the stability and air tightness of the soil in the palm surface can be improved by using cement mortar retaining wall,to solve the problem of safety knife change under the condition of water-rich composite strata.