新建地铁车站近距离穿越既有地铁隧道的变形控制

Deformation Control of a Newly-Built Subway Station Crossing the Adjacent Existing Subway Tunnel

以机场线东直门站上跨下穿既有地铁13号线东直门站站后折返线工程为背景,研究新建地铁车站近距离穿越既有地铁隧道时既有地铁结构变形控制的标准及技术。施工前对既有地铁结构进行检测加固。根据检测评估、模拟计算和安全检算等结果制定既有地铁结构变形控制标准,并将沉降控制值按关键施工工序进行分解。施工过程中,采用加垫方法和PLC液压同步控制顶升技术等主动控制沉降。监测数据表明:隧道结构与轨道结构保持密贴;线路的轨距、水平、变形缝开合度均未超出控制值;开挖中导洞阶段及盖挖法施作下穿结构边墙和底板阶段既有地铁结构沉降占总沉降的50%左右,是施工控制的关键阶段;变形缝差异沉降超出控制值,是施工控制的重点位置;变形缝附近沉降、差异沉降等受环境温度影响较大,是监控的重点区域。

Based on the case project of Dongzhimen Station of the Airport Line,which cutting over and crossing under the back-turning line behind Dongzhimen Station of the existing metro Line 13,the deformation control standard and techniques of newly-built subway station crossing the adjacent existing subway tunnel were studied.Before construction,the existing subway structure was measured and reinforced.The standard for the deformation control of existing subway structure was worked out according to the results of detection evaluation,simulation and safe checkup.The control values for settlement were assigned according to key construction steps.During construction,the settlement was actively controlled by the padding method and PLC hydraulic synchronous lift-up technique,etc.Monitoring data showed that the deformation tendency of the tunnel structure corresponded well with that of the track structure in the process of construction.The railway gauge and height difference of the two tracks did not exceed the allowable values.The settlement of the pilot tunnel excavation stage was about 50% of the total deformation,which was the key stage of the deformation control.The settlement and differential settlement nearby the deformation joint were influenced greatly by ambient temperature,where was the key monitoring and control area.