(1. College of Geology Engineering and Geomatics，Chang¢an University，Xi¢an，Shaanxi 710054，China； 2. Key Laboratory of Western Mineral Resources and Geological Engineering，Ministry of Education，Chang¢an University，Xi¢an，Shaanxi 710054，China；3. School of Civil Engineering，Chang¢an University，Xi¢an，Shaanxi 710054，China)
Abstract：Based on the engineering background of Xi¢an metro tunnel and the geological environment of Xi¢an ground fissure，the physical modeling experiment for horseshoe-shaped tunnel lining structure crossing the ground fissure with 40° is designed according to the similarity theory. The strains of concrete，longitudinal and circumferential reinforced bars，the peripheral soil pressure，convergence displacement of lining structure model，the soil deformation on the top of model and other macroscopical phenomena of deformation and damage are studied. It is shown that the deformation and damage style of monolithic horseshoe-shaped tunnel lining structure crossing the ground fissure with 40° is asymmetric with distortion，bending and shearing. The concrete circumferential crack range is 0.83D(D = 1.80 m) in the hanging side region，and 1.11D in the lying side region. The concrete longitudinal crack range is 1.11D in the hanging side region，and(1.94–2.22)D in the lying side region. The damage degree of structure in the lying side region is more serious than that in the hanging side region. The segmentation of lining structure shoud be used to fit the distortion，bending and shearing in the horseshoe-shaped tunnel crossing the ground fissure with 40°. Antitorque means should be used in the structure design，and the enlargered cross-section and high-performace concrete should be used to resist the shearing deformation.
