Study On The Soil Metro Tunnels Interactions In Ground Fissures Area

Xi’an, as the international metropolis in the world, the development of urban masstransit is imminent. However, Xi’an unique geological structure, a lot of ground fissures, hasbrought an unprecedented difficult problem for city construction. In this dissertation, takingground fissures in Xi’an as the engineering geology background, using the metro underconstruction in Xi’an as the main research object, based on the interaction theory betweensoil and structure, combining the theoretical analysis with experiments, mechanics analysismodel in the activities of the typical section of Xi’an ground fissure is established;computational mechanics model of gap at interface of subway tunnels is also constructed, andmechanics effects of the surrounding rocks around the gap at the bottom of tunnel in theinfluence of ground fissures activity are analyzed. The main research and results are asfollows:(1)On the basis of model test on subway tunnel crossing ground fissure, stress-straininfluencing rules of gap at the bottom of subway tunnel caused by the activities of groundfissure are expounded. The result is that when the tunnel crosses ground fissure, gap at thebottom of tunnel located on the hanging wall will be appeared inevitably and has afundamental impact to the stress of tunnel structure.(2)Through analyzing the rules of gap, computational model of longitudinal stress on thegap at interface of subway tunnels and their formula are constructed under the influence ofactive ground fissures.(3)For subway tunnel crossing ground fissures in various oblique angles, inconsideration of torsion action, stress calculation model of tunnel cross section under the stateof gap is established.(4)Base on the experimental study of subsection tunnel, in consideration of stiffness andstrength of tunnel structure, the reasonable subsection length of tunnel crossing groundfissure is determined.On the basis of existing research results, gap at the bottom of the underground structurebeing difficult to solve are discussed in this dissertation. These research methods and ideas have a wide application value for disaster prevention and reduction and engineering design ofunderground engineering across the ground fissures.This research is financially supported by the National Natural Science Foundation (No.40772183).