Mechanical behavior of underground pipe gallery structure considering ground fissure

The mechanical behavior of underground pipe gallery is a key research issue due to the static/dynamic states which exist in a ground fissure area.This study took an underground pipe gallery project in Xi’an,China as the research object.We analyzed the stress/strain characteristics of the pipe gallery structure and surrounding soil under static/dynamic conditions by the numerical simulation methods in detail.Based on the results,we proposed a theoretical calculation model for the pipe gallery structure considering the influence of the ground fissure,and combined with engineering examples for calculation and discussion.Subsequent results showed that:(1)the effective activity range of ground fissure on the deformation of the pipe gallery structure was mainly from 0.0 m(horizontal direction of ground fissure)to 32.0 m.In activity range,the pipe gallery structure is prone to failure,owing to the large soil deformation in the vertical direction;(2)with the increase of ground fissure settlement,a stress reduction area near the ground fissure appeared at the bottom of the hanging wall of the pipe gallery structure,and a local void phenomenon was revealed.The length of the local void is 6.0 m to 8.0 m under the maximum settlement(0.8 m)of the ground fissure;(3)Compared with the static conditions,the vertical and horizontal displacements of the pipe gallery structure and surrounding soil under the seismic action were little,and there were tensioncompression and torsion-shear effects in corner of the square pipe gallery structure(with a stress concentration phenomenon).The deformation law of pipe gallery structure and surrounding soil considering ground fissure and the theoretical model of pipe gallery structure established in this paper can provide reference for practical engineering.