地裂缝剖面形态对地铁隧道变形影响模型试验研究

Model test for influence of ground fissure profile pattern on deformation of metro tunnel

为揭示隧道底部脱空与结构纵向变形之间的对应关系,模型试验以西安地铁隧道穿越地裂缝带为研究背景,采用圆形地铁隧道结构,研究了在不同地裂缝剖面活动特征下的隧道纵向应变变化规律及其垂直位移。试验结果表明,随着错位量增加,隧道底部脱空区域扩展过程可分为3个阶段:共同变形阶段、临界脱空阶段和脱空发展阶段。针对地裂缝的不同剖面活动形式,隧道结构内部应力将出现很大差异,建议在施工中对应不同地裂缝带采取不同的施工方案。通过监控,结合模型试验的应力应变发展变化规律,可判断结构底部脱空的发展趋势,为西安地铁穿越地裂缝带的结构设计和安全运行提供重要的参考依据。

To reveal the corresponding relationship between the void beneath the tunnel bottom and the longitudinal deformation of the metro tunnel,a model test of circler tunnel is carried out under the research background of Xi＇an Subway passing through ground fissure active zones.The law of the longitudinal strain and the vertical displacement of the tunnel are studied caused by the different profile activity patterns of ground fissure belts.With the increase of the dislocation between the hanging wall and the foot wall of ground fissure,the test results show that the expansion process of the separation between the bottom of tunnel and the soil layer under the tunnel can be divided into three stages,i.e.co-deformation stage,the initial stage of void and the development of void.In view of different profile activity situations of ground fissures,the stress in the structure presents variance considerably.Different designs are suggested to different profile patterns of ground fissure belts.Under the law of stress and strain of the tunnel in the model test,the trend of the void beneath the tunnel can determined by monitoring the stress of structure.The results can provide reference for the structure design and the safe operation of metro tunnel.