Study On Construction Mechanical Effects And Asymmetric Support Of Shallow-buried Bias Neighborhood Tunnel

As the construction of urban roads and many grade highway in our country,thereare more and more tunnel project.Tunnel can straightened the road,and shorten the linemileage.But most of tunnel engineering construction in the wild,and greatly influencedby local geological and terrain factors,tunnel must adapt to changes in the geologicaland landform,thus many special forms of tunnel has been produced.In this paper,Shallow bias neighborhood tunnel for the study,from the angle of theoretical analysis,numerical simulation,studied the surrounding rock pressure and the effects ofconstruction mechanics and asymmetric support of shallow bias neighborhoodtunnel.The main research work and achievements are as follows:①Theoretically analyzed the distribution characteristics of the surrounding rockpressure of shallow bias neighborhood tunnel,and analysed the difference of distributionof surrounding rock pressure of left and right side or left and right tunnel of the shallowbias neighborhood tunnel.②A typical shallow bias neighborhood section of a tunnel is selected as theresearch object,analyzed the influence of excavation on stress and strain of surroundingrock and the changes of internal force of retaining structure when constructed with thesteps method. Analysis shows that the influence of excavation on surrounding rockdecrease with distance,the early constructed supporting structure is greatly influencedby the construction process.③Comparatively analysed the mechanical response of surrounding rock and liningstructure using steps、single side heading、twin side heading method.With twin sideheading method excavation method for the influence of surrounding rock is minimal,butthe largest stress in lining structure.And when excavation by steps method, the impacton the surrounding rock is the largest,but the lining structure stress is minimal.④Ground slope were analyzed in the certain fixed cases and left hole depth tunnelclear distance for the influence of surrounding rock and lining structure, analysis showsthat, after two hole interval increase in right hole depth increase, lead to the right holelining structure and the change of surrounding rock deformation is bigger, and changeof the left hole is smaller.⑤Analysed the asymmetric support of shallow bias neighborhood tunnel,Modeledand calculated the asymmetric support about single hole and double hole using shotcrete support and anchor support which is part of shotcrete and rockbolts supporting.Throughthe analysis shows that,for the shallow bias neighborhood tunnel,appropriately cut downthe supporting parameters of the less loaded side or hole to saving material and makefull use of the material.