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黄土地层浸水湿陷对地铁隧道结构的影响是较为突出的岩土工程问题之一,为深入研究黄土层湿陷变形对隧道衬砌结构的影响机制,通过改进长安大学离心机浸水装置和监测设备,系统开展了浸水条件下湿陷性黄土层对地铁隧道结构影响的离心模型试验,试验结果表明:地铁隧道周边黄土浸水湿陷会导致土层重度增加,隧道拱顶土层内部拱效应因湿陷而消散,土层自重压力增加且完全由隧道结构承担,从而会导致隧道结构受力和变形不利,传统的深埋隧道结构设计理论需考虑湿陷条件下拱顶土压力的不利增长因素;地铁隧道基底下黄土地基的浸水湿陷会明显诱发隧道结构的附加作用应力,但一定厚度的非湿陷性黄土或有效处理过湿陷性黄土层抵御下伏土体湿陷变形的能力不容忽略,非湿陷土层厚度越大,对于抵御湿陷变形的能力越强;隧道基底土层不均匀浸水湿陷会导致隧道拱顶部呈现受拉状态,底部呈现受压状态,隧道拱顶所承受的附加应力更大,约为拱底附加压应力的3倍,隧道基底的自重湿陷变形对隧道顶部衬砌结构所造成的破坏更严重。
The influence of submergence and collapse of loess stratum on the structure of metro tunnel is one of the most prominent geotechnical problems. In order to study the influence mechanism of loess deformation on tunnel lining structure, by improving the centrifuge flooding device and monitoring equipment of Chang’an University, Centrifuge model tests on the influence of collapsible loess layer on subway tunnel structure under flooding condition were carried out. The experimental results show that the subsidence of loess water around subway tunnel can lead to severe increase of soil layer, and the internal arch effect of tunnel dome layer due to the collapse However, the pressure of self-weight of soil increases and is completely borne by the tunnel structure, which will result in unfavorable stress and deformation of the tunnel structure. The traditional theory of deep tunnel structure design needs to consider unfavorable growth factors of vault earth pressure under collapsing conditions. Submergence and collapse of loess foundation under tunnel foundation can obviously induce additional stress of tunnel structure. However, the capacity of a certain thickness of non-collapsible loess or effective treatment of collapsible loess layer against the deformation of subsoil collapse can not be neglected, The larger the thickness of non-collapsible soil layer, the stronger its ability to resist the deformation of collapsible soil. The uneven water-soaked subsidence of tunnel foundation soil The top of the tunnel arch is under tension and the bottom is under compression. The additional stress applied to the dome of the tunnel is larger, which is about 3 times of the additional compressive stress on the bottom of arch. The self-weight of the tunnel foundation collapses to the lining structure of tunnel The damage done is even more serious.