Influence Of A New Tunnel Construction On The Adjacent Existing Tunnel

With the development of railway construction in China, more and more new multiple tracks are soon put into construction. Because of topography and geology limit, nevv tunnel is close to existing tunnel, which frequently results in destruct existing tunnel structure and afifected safe run. These situations disturb safe construction of new tunnel, so it is necessary to research reliable construction technology of close-spaced tunnel.Under the direction of elastic-plastic statics theory, transient dynamics theory and structure mechanics theory, the means of numerical analyse is adopted in this thesis to study the security of existing tunnel. The thesis studies the contents as follovvs:(1) The bias pressure, vvhich is caused by the digging of new tunnel, deflectsand deforms the lining of existing tunnel. The effect degree relates to tunnel space, construction method, topography and round rock.(2) If the tunnel is constructed by blasting method, the shock \vave from blasting endangers the safety and stabilization of existing tunnel structure. Under the effect of instantaneous blasting shock wave, the reliability of lining is affected. The influence on existing tunnel relates to amount of dynamite, tunnel space, area of vvok face and rigidity of round rock.(3) Some destroy is likely to occur to existing tunnel before new construction, that is to say, the tunnel perhaps holds some flaw, therefore, a structure mechanics method is used in this thesis to analyze the safety of existing tunnel vvhich is under the condition of back cavity and insufficient thickness.