基坑开挖对下卧运营地铁隧道影响的数值分析与变形控制研究

Numerical analysis of effect of excavation on underlying existing metro tunnel and deformation control

以紧邻已运营天津地铁1号线既有隧道箱体上方的西青道下沉隧道基坑工程为背景,结合现场实测数据,采用ABAQUS软件对基坑的实际施工过程进行动态模拟。在此基础上分析既有隧道箱体两侧的土体加固、浇筑底板与抗浮桩形成"保护箍"以及堆载回压等措施对既有箱体轨道的影响及其有效性,指出有针对性地综合采用上述保护措施,能够及时有效地控制既有箱体轨道上抬,保证地铁的安全运营,并进一步研究了不同加固参数对既有箱体轨道变形的影响规律,结果表明:提高各加固参数能减小箱体轨道上抬及变形缝处的箱体间差异变形,但其加固效果却随着参数的增加而减弱,存在着一个合理的参数范围,为施工设计的优化提供依据。

According to the practice of the excavation of the Xiqing Road Tunnel adjacent to the existing tunnel of the operating Tianjin Metro Line l, ABAQUS is applied to simulate dynamically the construction process based on the field monitoring data. On this basis, the effects and the effectiveness of the soil reinforcement alongside the existing tunnel, a protection hoop formed by the slab and anti-floating piles and the reverse heap-loading on the track deformation of the existing tunnel are analyzed. It is found out that the above protection measures adopted synthetically can timely and effectively control the uplift of the track in the existing tunnel and ensure the safe operation of metro. Furthermore, the effect law of the different reinforcement parameters on the track deformation of the existing tunnel are studied. The results show that the increase in the different reinforcement parameters can reduce the up lift of the track in the tunnel and the different deformations between the two adjacent boxes of deformation joint, but the reinforcement effect decreases with increase of the parameters; and there exists a reasonable scope of the reinforcement. The results can provide evidence for the optimization of the construction design.