盾构隧道下穿老旧建筑物群微沉降控制技术研究

Micro-settling control technology for shield tunnels crossing old buildings

中心城区盾构隧道下穿老旧建筑物的沉降控制是盾构施工的焦点问题。通常沉降控制方法是通过地表沉降监测数据,决定是否进行二次注浆,但地表及建筑物变形早已发生。为了弥补传统方法沉降处置滞后的不足,提出了“微沉降”施工控制技术,开发了壁后注浆雷达实时检测系统与自动化监测预警平台,在地表沉降发生之前及时注浆填充地层损失的空隙,防止地表沉降,保证老旧建筑物安全。济南轨道交通R3线王-裴区间隧道下穿越的老旧建筑物群,建造时间多为20世纪70-80年代,部分墙体风化严重,大大增加了地表沉降控制、建筑物保护难度。首先,利用三维有限元软件,对隧道下穿苏宁大楼和农业银行进行三维数值模拟,认为适当增加注浆压力可以有效减小地表沉降值,模拟结果与监测数据较为吻合。其次,为了掌握壁后注浆质量,控制隧道下穿化肥厂宿舍楼时的地表变形,开发了壁后注浆雷达实时检测技术,在衬砌拼装间隙检测注浆质量,动态调整注浆压力及注浆量,有效控制了地表沉降。同时,项目采用自动化监测和人工监测联合的监测方案,实时监测建筑及地表变形,并通过移动端手机应用实时掌握变形情况,可及时采取措施。利用雷达实时检测结果与地表监测结果,地上地下联动,地表沉降被控制在5 mm之内,最终基本实现了“微沉降”的目标,建筑物得到了良好的保护。

The settlement control of shield tunnels in the central cities crossing the old buildings is increasingly the focus of shield construction.Generally, the settlement control method is the secondary grouting according to the surface subsidence monitoring data, but deformations of surface and buildings have already occurred.In order to make up for the shortcomings of the traditional method, the construction control technology of "micro-settling" is put forward, which includes a real-time detection technology for grouting behind segments by using the radar and automatic monitoring and warning platform and takes measures before surface deformation.It is applied to the Wangsheren-Peijiaying interval tunnel of Jinan Rail Transit R3 line under-passing through the old buildings.The construction time of the buildings is mostly in the 70 s and 80 s of the twentieth century.Some of the walls are severely weathered, which greatly increases the difficulty to control the surface settlement and protect the buildings.Firstly, by using the three-dimensional finite element software PLAXIS 3D, the numerical simulation of the tunnel crossing the Suning Building and Agricultural Bank of China is carried out.It is considered that increasing the grouting pressure can effectively reduce the surface settlement.The simulated results are in good agreement with the monitoring data.Secondly, in order to control the surface deformation of the tunnel crossing the dormitories of Chemical Fertilizer Plant, the real-time detection technology of the post-grouting by radar is developed.The grouting quality is detected during segment fixing, and the grouting pressure and capacity are dynamically adjusted to effectively control the surface settlement.At the same time, the project uses a combination of automatic and manual monitoring devices to monitor real-time deformation of buildings and surface.The engineers can grasp the construction information through the mobile phone applications, and timely measures can be taken.Combing the real-time radar detection results and surface monitoring results, the ground settlement is controlled within 0^-5 mm, and finally the goal of “micro-settling” is achieved. The building has been well protected.