地面堆载下既有盾构隧道韧性评估和注浆加固机理研究

In recent years, the engineering cases of deformation-induced structural diseases of existing shield tunnels under surcharge have increased, which become major threats to the safe operation of urban subway. Grouting method offers an effective way to reduce the tunnel deformation and ensure the structural safety. However, the deformation mechanism of shield tunnel during the grouting process is not fully understood, which makes it difficult to determine the reinforcement time and ensure the grouting effect. In this project, the resilience evaluation and grouting mechanism of existing shield tunnel under surcharge are systematically studied by numerical simulation, model test and analysis of field measurements. Through the establishment of both the transverse and longitudinal resilience indexes of the shield tunnel, the development of the tunnel structural performance under surcharge and unloading is studied. Model test and refined numerical analysis are conducted to study the development of the horizontal convergence and longitudinal segment dislocation of the shield tunnel during the grouting process, and then the grouting effect on the tunnel resilience is comprehensively evaluated. The theories of structural safety evaluation and grouting reinforcement of existing shield tunnel are established, which can provide theoretical support for the scientific determination of reinforcement time and the rational design of grouting scheme.

近年来，既有盾构隧道受地面堆载影响产生较大结构变形，进而诱发结构病害的工程案例逐渐增多，严重威胁城市地铁的运营安全。注浆加固法能够有效减小已发生的隧道变形，保证隧道结构安全。目前针对注浆过程中盾构隧道的受力变形机理的理论研究不够充分，导致注浆加固时机难以确定，注浆效果无法得到可靠保证。本项目拟通过数值分析、模型试验和现场实测分析等方法，对地面堆载下既有盾构隧道韧性评估和注浆加固机理开展系统研究。通过建立盾构隧道横、纵向韧性评价指标，研究地面堆卸载下隧道结构性能的衰变和恢复机制；采用模型试验和精细化数值分析相结合的方式，研究注浆过程中盾构隧道水平收敛和纵向管片错台的变化规律，并综合评估注浆法对盾构隧道韧性的提升效果。通过上述研究建立盾构隧道结构安全评价和注浆加固理论体系，可为加固时机的科学选择和注浆加固方案的合理设计提供理论支撑。

本项目以深圳市地下空间开发过程中运营盾构隧道保护问题为背景，针对地面堆载下盾构隧道结构韧性评估和加固修复难题，通过一系列理论、数值仿真、现场实测和模型试验研究，取得了以下成果：提出了考虑历史最大变形影响的隧道衬砌性能指标，并通过三维精细化数值仿真，揭示了地面堆卸载作用下隧道结构响应特征和韧性演化规律；提出了基于自钻式旁压试验的花岗岩残积土本构参数反演方法，建立了隧道纵向变形数值仿真模型，结合自动化全站仪、三维激光扫描和高清摄影等现场实测数据，阐明了隧道在纵向不均匀位移下的病害演化机理；开展了盾构隧道注浆加固模型试验研究，研究了注浆作用下隧道结构内力与变形演化规律，并通过参数化分析，探明了不同注浆顺序对隧道纠偏效果的影响规律，优化了注浆施工顺序。本项目的研究成果可为城市运营地铁隧道韧性评估、安全预警和加固修复提供理论基础和技术支撑，