复杂环境盾构工作井超深基坑监测分析

Monitoring and Analysis of Ultra-deep Foundation Pit of Shield Working Well

以穗莞深城际前海至皇岗口岸段工程某超深盾构机工作井基坑为背景,对围护结构支撑轴力、周边地表沉降、基坑外地下水水位变化、周边建筑物沉降及倾斜进行监测,分析超深基坑施工对围护结构受力、地层变形性状和对周边环境的影响。结果表明:该基坑施工引起地表沉降的累计最大沉降量达到78.71 mm(红色预警值72.00 mm);坑外地下水位降水累积变化值正常;周围建筑物累计沉降量100.00%达到红色预警值,最大倾斜率为0.47‰;混凝土支撑轴力监测反映基坑支护体系处于安全状态。针对性地采取工程技术与管理措施,主要为清除基坑周围堆放的建筑废渣,并在运输路面铺放钢板以均布动荷载,加强基坑周围巡护;对土层进行劈裂注浆加固;实时监测和反馈分析,确保监测数据在可控范围内等,保证施工整体安全。

Taking the foundation pit of ultra-deep shield working well as the background of Suiguanshen Intercity Qianhai to Huanggang Port project,the monitoring of the support axial force of the enclosure structure,the surrounding surface settlement,the change of the groundwater level outside the pit,and the settlement and tilt of the surrounding buildings was carried out.The impact of construction of the ultra-deep shaft pit on the force of the enclosure structure,deformation of the stratum,and the surrounding environment was analyzed.The results show that:during the pit construction,the surface settlement was caused,and the cumulative maximum settlement reached 78.71 mm(the red warning value was 72.00 mm).The precipitation accumulation of underground water level outside the pit was normal.The cumulative settlement of the surrounding buildings reached the red warning value by 100.00%,and the maximum tilt rate was 0.47‰.The axial force monitoring of concrete support reflects that the foundation pit supporting system is in a safe state.The main targeted engineering technology and management measures taken are as follows:clearing the construction debris piled up around the pit and laying steel plates on the transport road surface to uniform the dynamic load,strengening the patrol around the pit.The soil layer is reinforced by splitting grouting.The real-time monitoring and feedback is analyzed to ensure that the monitoring data is within the controllable range.The above measures ensure the safety of the construction as a whole.