Surcharge due to improper soil dumping and irregular backfilling often causes excessive deformation along the adjacent shallow tunnel in soft-soil areas. Tunnel structures are usually modelled with beam elements where the bending of the concrete segments is considered while the shearing dislocation between segmental rings is usually ignored. In this work, a Timoshenko beam was used to consider such dislocation of a shield tunnel under surcharge and a Pasternak foundation was used to account for the tunnel–soil shear effect. A numerical method was then developed to assess the effect of surcharge loading on the longitudinal responses of the underlying tunnel based on a two-stage method. The proposed solutions were verified using a case history from Shanghai and a three-dimensional numerical simulation from the literature. Results of a further parametric study showed that the deformation induced by surcharge loadings would be underestimated without the shearing-induced dislocation of tunnel segments, which could overpredict the serviceability of the underlying tunnel in surcharge accidents.

中文翻译：

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考虑错位超载的盾构隧道纵向响应

由于土壤倾倒不当和不规则回填造成的超载往往会导致软土地区沿相邻浅层隧道过度变形。隧道结构通常用梁单元建模，其中考虑了混凝土管片的弯曲，而通常忽略了管片环之间的剪切错位。在这项工作中，使用 Timoshenko 梁来考虑超载下盾构隧道的这种错位，并使用 Pasternak 基础来考虑隧道 - 土壤剪切效应。然后开发了一种基于两阶段方法的数值方法来评估超载载荷对底层隧道纵向响应的影响。使用来自上海的案例历史和文献中的三维数值模拟验证了所提出的解决方案。