Failure analysis of urban open-cut utility tunnel under ground fissures environment in Xi’an, China

Abstract There are 14 ground fissures covering the urban area of Xi’an, China, which will undoubtedly bring severe challenges to the construction of urban underground utility tunnel. This study focuses on the failure mechanism and deformation characteristics of utility tunnel based on Kunming Road utility tunnel crossing f3 ground fissure by finite difference numerical simulation. The results show that the integral utility tunnel(IUT) is inevitably failure when crossing ground fissure, the void area with the width of 18 m is formed at the floor of IUT on hanging wall, it has the bending failure under the tension and shear force due to too large tensile strain. To ensure the safe construction of utility tunnel, the segmented measures are suggested in this study, and is verified by numerical simulation that the deformation and force of segmented utility tunnel(SUT) can be alleviated after taking the segmented measures, the range of failure area is reduced by 47.7%, the tensile strain of utility tunnel is reduced by 90.3%~92.2%, and the void area of utility tunnel can also be eliminated, which indicates that segmented utility tunnel(SUT) can adapt to the movement of ground fissures without failure. This study can be helpful in developing utility tunnel in ground fissures area.