RESEARCH ON THE DEFORMATION AND FORCE CHARACTERISTICS OF UNDERGROUND UTILITY TUNNEL CROSSING GROUND FISSURE

This paper takes the Kunming road underground utility tunnel crossing through f3 ground fissure in Xi'an city, China as research object. The deformation and force characteristics of underground segmented utility tunnel is analysed with finite element numerical simulationmethod. The results show that the vertical settlement deformation at the roof of underground utility tunnel exhibits reverse-S shape as a whole, and increases with the settlement of the hanging wall of ground fissure increasing. The longitudinal deformation of underground utility tunnel can be divided into three deformation sections:warping deformation section at the hanging wall of ground fissure, differential settlement section, and integral deformation section at the footwall of ground fissure. Under the action of ground fissure with a vertical dislocation 50 cm in the design life of 100 years, the horizontal displacement peak value of utility tunnel roof appears in the position of ground fissure zone. The maximum values are 4.1 cm on roof and 3.2 cm on the floor of utility tunnel. The joints between utility segmented tunnels is easy to pull apart and be damaged and should be reinforced. Nearby the ground fissure zone, the contact pressure between the utility tunnel floor and soil stratum decreases to 0 at the hanging wall with the increase of vertical dislocation of ground fissure and underground utility tunnel floor appears disengaging phenomenon. Grouting holes should be reserved convenient to grouting treatment, But the contact pressure between underground utility tunnel roof and soil stratum has an increase trend. The strain of the underground utility tunnel roof and floor exceeds the limit of the concrete strain when settlement of the hanging wall of ground fissure reaches 20 cm. Therefore, the deformation and failure mode of the underground utility tunnel is mainly tensile failure under the action of ground fissure. The research can provide a scientific basis for engineering design of underground utility tunnel crossing ground fissure zone in Xi'an city and other developed areas of ground fissure.