Research On Excavation Method And Mechanics Behavior Of Large-span Tunnel Intersection

The subway station needs a big span tunnel because of its large building space.Andthe construction technology requirement of long-span subway station is very high anddifficult. The stress and strain of shield tunnel is very complex, so excavating tunnelmust be very careful.Otherwise, the tunnel may be collapsed.If a cross tunnel isexcavated in the long span of the tunnel wall,the stress relationship is more complex,and the construction is more difficult.At present, the theoretical analysis of the largespan cross tunnel is not very enough,and its working mechanism is not very clear.Therelated research at home and abroad is very rare,and the related research and applicationis still in the exploratory stage.Due to the lack of systematic and comprehensivestudies,the design theory and construction methods also is not mature.Based on the T shape cross region of Western International Convention andExhibition Centre supporting the Municipal Traffic Engineering in Chongqing-HuangMao Ping station with No.3entrances, and the cross-shaped region of Huang Mao Pingstation with No.3and No.4entrances,this paper analysises and simulates the entireexcavation process of T shape cross region and cross-shaped region,using the generalfinite element numerical analysis software ANSYS.And combining the constructionmonitor measuring data,the paper researches the construction mechanics characteristicof long-span cross section:Using numerical simulation method,the paper makes simulation with threedifferent conditions mainly:two side-wall pilot tunnel method,CD method and bench cutmethod.And according to the actual situation,the reasonable construction method isused, so as to reach being feasible in technique, reasonable in economy, and guaranteedin security.The paper studies the mechanical characteristics of T shape cross region andcross-shaped region under different conditions,and analysises the variation of rockstress and displacement during the construction process,and then discusses a variety ofexcavation methods and segment order impacting on the intersection.After analysising the monitoring data of the cross-section, the subsidencesituation of tunnel’s vault and spandrel,the level restraining,and the stress situation ofthe supporting and protectionsing structure,the paper elaborates the stress situation ofrock and initial supporting during excavation process of cross-regional.Finally,thispaper discusses the deformation law of Long-span tunnel’s cross-regional.