RESPONSE ANALYSIS OF DEFORMATION AND INTERNAL FORCE OF UN￣DER￣GROUND UTILITY TUNNEL CROSSING ACTIVE GROUND FRACTURE

Due to the limitation of site conditions,the construction of Xi'an's underground utility tunnel needs to cross the ground fractures at different angles,which can be affected by the action of ground fractures. A three-dimensional finite element model of an underground utility tunnel crossing an active ground fracture is established. When the underground utility tunnel crossed the ground fracture orthogonally,6 different settlement conditions of 5 cm,10 cm,15 cm,20 cm,25 cm and 30 cm,and 3 crossing angles of orthogonal,oblique angle of 60°and oblique angle of 30°are set up. The research results show that the deformation and axial stress of the underground utility tunnel increase with the increase of ground fracture activity. The horizontal displacement,vertical displacement and axial stress of the underground utility tunnel are concentrated in a certain range on both sides of the ground fracture. The peak value of axial stress on the upper surface of the underground utility tunnel is greater than that on the lower surface. The smaller the intersection angle between the underground utility tunnel and the ground fracture,the smaller the horizontal displacement of the underground utility tunnel,the larger the influence range of the vertical displacement,and the greater the axial stress of the underground utility tunnel. The actual project has to avoid the underground utility tunnel from crossing the ground fractures with strong activity at a small angle without joints. The research results have certain reference value for the analysis of the interaction mechanism between the soil body and the underground utility tunnel,as well as for disaster prevention and mitigation.