下穿地铁车站冻结加固冻胀与融沉控制技术

基于某沿海城市新建地铁车站密贴下穿既有运营地铁车站暗挖通道水泥改良土地层二次冻结加固工程,通过既有地铁车站轨行区的自动化监测系统,分析既有运营车站下方土体冻结后,冻结过程中的冻胀及解冻后冻土消融对既有地铁车站的影响。在冻结前,提前对冻结区域土体进行注浆加固,改善冻土参数,降低冻胀对既有运营车站的影响。在冻结过程中,采取冻结区域止水、对冻土进行取土泄压、调整冻结顺序、调节冻结温度、开启泄压孔进行压力泄压、控制冻结盐水流量和优化开挖方式等措施,有效减缓冻土对现有地铁车站的的影响。在暗挖通道结构施工完毕后,通过填充注浆和融沉注浆2种方式,解决土体冻结消融后既有地铁车站沉降的问题。

Based on the secondary freezing and strengthening project of the cement improved soil layer of the newly built subway station in a coastal city,through the automatic monitoring system of the track area of the existing subway station,the influence of frost heave in the freezing process and thawing of permafrost on the existing subway station is analyzed through the automatic monitoring system of the track area of the existing subway station.Before freezing,the soil in the frozen area should be reinforced by grouting in advance to improve the permafrost parameters and reduce the impact of frost heave on the existing operating stations.In the process of freezing,some measures are taken,such as stopping water in frozen area,taking soil to relieve pressure,adjusting freezing sequence,adjusting freezing temperature,opening pressure relief hole,controlling frozen salt water flow,optimizing excavation mode and so on.Effectively slow down the impact of permafrost on existing subway stations.Through the completion of the construction of the underground Excavation channel structure,the problem of settlement of the existing subway station after soil freezing and thawing can be solved by filling grouting and melting grouting.