ISSN 1000-3665 CN 11-2202/P

    盾构隧道穿越岩溶地层安全距离预测模型

    Prediction model of safe distance for shield tunnel crossing karst strata

    • 摘要: 盾构隧道施工穿越复杂岩溶地层时,会造成较大的施工扰动,从而显著增加地表过大沉降或局部坍塌的风险,严重威胁盾构施工安全。以济南轨道交通4号线唐冶站至程家庄站区间盾构隧道穿越岩溶地层段为研究背景,采用数值模拟方法研究隧道上穿及侧穿溶洞时的围岩位移场、塑性区的演化规律,并对模拟结果进行回归分析,根据塑性区贯通原则,考虑围岩等级、隧道埋深以及溶洞洞径三种因素的正交试验方案,分别建立隧道上穿以及侧穿溶洞的溶-隧安全距离预测模型。结果表明:隧道上穿溶洞时,随着溶-隧间距增加,拱底隆起增加,拱顶沉降减小,左右拱腰水平位移减小,塑性区贯通趋势减小;隧道侧穿溶洞时,随着溶-隧间距增加,拱顶沉降减小,近溶洞一侧的拱腰水平位移减小,塑性区贯通趋势减小。溶-隧安全距离随着各因素的增加而增加,不同因素的影响程度表现为:溶洞洞径>围岩等级>隧道埋深。通过理论分析和预测模型,应对唐冶站至程家庄站区间盾构隧道下方5 m以及侧方3 m的范围进行加固。研究成果为济南轨道交通4号线盾构隧道穿越岩溶地层段围岩加固提供了理论依据,对于指导现场施工具有重要意义。

       

      Abstract: Shield tunneling through complex karst formations presents significant engineering challenges due to construction-induced disturbances, which markedly increase the risk of excessive ground settlement and localized collapses. These phenomena pose serious threats to the safety and stability of tunneling operations. For the shield tunnel section between Tangye Station and Chengjiazhuang Station of Jinan Metro Line 4, numerical simulation methods were employed to analyze the evolution of the surrounding rock displacement field and plastic zone when the tunnel crosses karst caves above and laterally. Regression analysis was conducted on the simulation results. Based on the principle of plastic zone penetration, orthogonal experimental schemes considering three factors (surrounding rock grade, tunnel burial depth, and karst cave diameter) were developed to establish predictive models for the safe distance between karst caves and tunnels for both overhead and lateral crossings. The results indicate that when the tunnel crosses a karst cave overhead, as the distance between the cave and tunnel increases, the uplift at the tunnel invert increases, the settlement at the tunnel crown decreases, the horizontal displacements at the left and right tunnel haunches diminish, and the trend of plastic zone penetration weakens. When the tunnel crosses a karst cave laterally, with increasing distance between the cave and tunnel, the settlement at the tunnel crown decreases, the horizontal displacement at the tunnel haunch on the side closer to the cave diminishes, and the trend of plastic zone penetration also weakens. The safe distance between karst caves and tunnels increases with each factor. The extent of influence of different factors is ranked as follows: karst cave diameter > surrounding rock grade > tunnel burial depth. Through theoretical analysis and predictive models, reinforcement measures should be implemented within a 5 m radius below and a 3 m radius laterally of the shield tunnel section between Tangye Station and Chengjiazhuang Station. This study provides a theoretical basis for reinforcing the surrounding rock of the shield tunnel section crossing karst formations on Jinan Metro Line 4, which is of great significance for guiding on-site construction.

       

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