盾构施工对建(构)筑物沉降监测及分析

对西安市朝阳门护城河老桥和明城墙安全防护设计提供必要的基础参数,以确保其在地铁一号线盾构施工中的安全,特在该路段建立了建(构)筑物及其周边地表变形监测系统,跟踪测试了朝阳门护城河老桥和明城墙在盾构施工过程中的一系列变形特征,并通过图表的形式展示了各建(构)筑物等变形随时间的变化规律,进而分析了其整体变形状态和沉降的趋势。结果表明:护城河老桥最大累计沉降量为5.1 mm,最大差异沉降量为1.6 mm,最大累计桥拱沉降量为2.4 mm,最大累计桥拱收敛为1.8 mm;朝阳门城墙主体和周边地表最大累计沉降量分别为4.5和5.2 mm;各监测项目最大累计沉降量均在控制值之内;现场无新增裂缝、无凹凸现象,隧道内无渗水情况,表明该路段在盾构机掘进过程中无不利突变现象;结合现场监测和巡视情况,可判定盾构机在穿越护城河和城墙期间,对该段建(构)筑物变形影响较小,老桥和明城墙处于安全可控状态。本次监测可为后期地铁工程的设计、建设和维修管理提供经验。

Monitoring and analyzing of subsidence by shield construction

It was provided that the necessary safety protection design parameters which is to ensure the security of Xi ＇ an Chaoyangmen moat old bridge and Ming city wall in the metro shield construction. The deformation monitoring system of the building and surrounding ground surface was setted up in this stretch of road. A series of deformation characteristics of ChaoYangMen moat the old bridge and Ming city wall in the shield construction were tracking tested. And the variation regularity of buildings deform- ation with times were showed through the form of charts. And then the whole deformation conditions and the trend of settlement were analysed. The results were showed that ： the moat old bridge maximum cumu- lative settlement was 5.1 mm. The maximum differential settlement was 1.6 mm. The largest cumulative arches settlement was 2.4 mm. The largest cumulative arches convergence was 1.8 mm. ChaoYangMen wall body and surrounding surface maximum cumulative settlement were 4.5 and 5.2 mm. The largest cumulative settlement of the monitoring project was within the control values. The scene of no adverse mutation phenomenon in the process of shield tunneling was indicated because of without new crack, or bump phenomenon, or no water seepage in the tunnel. Combined with field monitoring and patrolling, the built deformation was less affected and in the safe and controllable state during shield machine crossing the moat and the wall. The experience is provided for the later operation and maintenance management.