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多线叠交盾构隧道在地下空间内布置形式繁多,土体-隧道间相互作用机制复杂。针对多线叠交盾构垂直上穿、垂直下穿和上、下夹穿3种典型穿越施工形式,根据盾构隧道近距离施工的技术特点和控制要求,采用排液法重点分析了施工中因地层损失和开挖卸荷引起的地表沉降以及既有隧道纵向变形规律,并通过构建三维弹塑性有限元动态模型,与部分试验结果进行了对比验证。研究结果表明:上穿施工中,地表沉降较大,既有隧道均呈现上浮趋势;下穿施工时,地表沉降较小,既有隧道均呈现下沉趋势;先下后上穿越施工在各阶段引起的地表沉降变化均匀,最终地表沉降量相对较小;先上后下穿越施工时既有隧道变形曲线曲率大,既有隧道变形呈现反复震荡变化。成果可为类似多线叠交隧道工程的施工提供理论指导。
Multi-track overlapped shield tunnels are arranged in underground space in various forms, and the soil-tunnel interaction mechanism is complex. According to the technical characteristics and control requirements of the shield tunnels for short-distance construction, aiming at the vertical piercing, vertical piercing and vertical piercing of the multi-strand crossweb shield, Surface subsidence due to formation loss and excavation unloading, as well as the longitudinal deformation of existing tunnels, and through the construction of three-dimensional elasto-plastic finite element dynamic model, and some experimental results were compared and verified. The results show that the settlement of the ground surface is relatively large during the construction of the upper ground, and the existing tunnels all tend to float upward. During the construction of the lower ground, the settlement of the ground surface is small, and the existing tunnels all show the tendency of sinking. The surface subsidence caused by the change is uniform and the surface subsidence is relatively small. The curves of the deformation of the existing tunnels are large firstly, and the deformation of the existing tunnels shows repeated oscillatory changes. The results can provide theoretical guidance for the construction of similar multi-lane overlapped tunnel project.