Study On Deformation And Failure Mechanism And Mechanics Model Of Shield Tunnel Under The Influence Of Active Buried Ground Fissures

With the development of the west in China and economic development of the westernregion, Xi’an became one of25cities where China approved of metro construction for thefirst time in2006.Metro construction in Xi’an is not only the need of alleviating the pressureof urban transportation and meeting the need of urban travel,but also the need of promotingeconomic sustainable development of Xi’an.However, ground fissures in Xi’an, the famousunique and complicated geological disasters, is a difficult problem for metro construction inXi’an.The first ground fissure in Xi’an was found in the1950s and there are in all14groundfissures till now and they are also in constant activity.Metro will inevitably interlaced withthese ground fissures during metro construction process,and then ground fissures will affectthe stability of surrounding rockmass inevitably.Thus metro will be damage which willbecome the hidden trouble for metro safety operation. Therefore, in order to guarantee thedevelopment of urban rail transit smoothly in later stage,the problem of metro tunnel goingthrough the ground fissures became an important subject in the construction of metro in Xi’an,especially the influence of ground fissure to metro construction has been attached greaterimportance.In this dissertation, according to the deformation and failure results of three largephysical model tests for shield tunnel in buried ground fissures, combined with finite elementmethod, the deformation and failure of shield tunnel crossing through the ground fissures inthe action of ground fissures activities are studied and the following achievements have beenobtained:1According to large physical model experiment of shield tunnel intersection withground fissures from different the angle of30°,60°and90°under the action of buriedground fissures,damage types and area of influence are basically clear and the relationshipbetween the angles and the width of shield lining failure region are determined.2Through the finite element numerical simulation of shield tunnel lining under theaction of buried ground fissures in different angles, the distribution of shield lining soffit gapare obtained and the relationship between the angles and vertical displacement of shield liningare determined. 3Under the action of buried ground fissures activities, the influencing rules of the angleto deformation and stress of shield tunnel lining are studied.4Under the action of buried ground fissures activities, stress model and calculationmodel of shield segment are established.In addition, the deformation and failure mechanism of shield segment under the action ofburied ground fissures activities are studied in this dissertation, which enriches the interactiontheory between metro and ground fissures and is very important value for the design andsafety testing of xian metro engineering under the environment of buried ground fissures.