Deformation Characteristics Of Shallow Gaoshan Yan Tunnel Under Unsymmetrial Loading And Its Optimization Of Construction Schemes

In this ages,the development and utilization of underground space become more important.And the development of highway tunnel engineering brings the new problems such as shallow depth,uneven ground pressure.Loading is distributed unsymmetrically which acting on supporting structure after excavation of tunnel,and would result in the deformation and crack of primary support.Furthermore,It can also lead to the crack of secondary lining with surrounding rock undering high pressure.So that It has an important significance to investigate the deformation characteristics of unsymmetrical loading tunnel.Based on the shallow tunnel with unsvmmetrical loadings of Gaoshan Yan tunnel in Fujian Proving,the field monitoring and indoor triaxial rate sensitivity test were both carried out to establish an elastic-viscoplastic constitutive model of tunnel surrounding rock.The three dimensional elastic-viscoplastic deformation numerical analysis of tunnel was realized by the UMAT subroutine implemented into the finite element software such as ABAQUS,to provide the beneficial reference for the evaluation of tunnel stability and safety of supporting structure,the main contents include:In this research,necessary items of tunnel monitoring measurement was discussed firstly,the geological sketch,displacement of convergence,vault crown settlement and ground settlement were measured to reflect the tunnel stability.Prediction results were feed back to construction site timely to direct the construction.Through the indoor triaxial rate sensitivity test,this paper studied the strength deformation characteristics of granite.Based on this,the influence law of strength affected by the loading rate were investigated as well.The results show that the Elastic Modulus and peak stress of granite enhanced in fine with the increase of stress loading rate.With the increase of loading rate,Peak strain increases firstly then decreases.Moreover,it can be observed that there are a critical loading rate.Lastly,ABAQUS was used to simulated the excavation of tunnel.A advisable construction scheme which can ensure the construction safety,improve the construction speed and reduce the construction cost in the meantime simultaneously,was obtained by comparing with different construction method.Additionally,deformation of surrounding rock and stress distribution of supporting structure under different partial pressed angle and buried depth were also discussed in detail.Hence,it can give a insight into the stability of surrounding rock during excavation of tunnel.