上方基坑开挖由于应力释放及坑底回弹,不可避免导致既有隧道产生上浮变形,长距离共线时其影响更为显著.在考虑环间剪切错台变形的铁木辛柯简化模型基础上,结合Winkler地基模型,提出了一种上方基坑开挖下土-隧道相互作用解析模型.利用叠加原理将该模型应用于上方长距离基坑开挖引起的共线隧道变形实例分析.通过计算结果与实测数据对比验证了该模型的准确性.分析结果表明,上方主体结构施工后,隧道上浮变形明显回落,但局部差异沉降增加,导致隧道内力和环缝变形显著增加.隧道渗漏水位置并非位于隧道上浮变形最大处,而是位于接头张开量最大处与接头错台变形最大处之间.因此,实际工程中不应仅关注隧道总变形,同时应关注差异沉降引起的接缝张开及错台变形.虽然隧道变形中剪切变形占比约为21.41%,但其引起的接缝错台变形较为显著,其对接缝防水有重要影响,理论分析中不容忽视.

Overlying excavation will inevitably cause uplift of the existing tunnel due to the stress relief and rebound of soil, and the impact will be more significant when the long-distance is in line. Based on the Timoshenko simplified model of tunnel which considers the shearing dislocation between rings, and combining with the Winkler foundation model, an analytical model for soil-tunnel interaction analysis of overlying excavation was established. Based on the superposition principle, the model proposed was applied to a case study of tunnel deformation induced by overlying long-distance collinear excavation. By comparing the calculated results with the measured data, the accuracy of the proposed model was verified. The analysis results show that after the construction of the upper main structure, the uplift deformation of the tunnel has significantly decreased, but the local differential settlement increases, resulting in a significant increase in the internal force of the tunnel and the deformation of the annular joint. The groundwater leakage generally occurrs not at the location with the maximum uplift of tunnel, but between the location with the maximum opening of joint and the location with the maximum shearing dislocation. As a result, not only the total deformation but also the opening and dislocation deformation of joints caused by differential settlement should be concerned in practice. Although the shear deformation generally accounts for about 21.41% of tunnel deformation, the induced shearing dislocation is significant compared with the opening caused by bending, which can be more important for waterproof in joints. The analytic model should not neglect the shearing deformation of the tunnel.