Deformation And Control Of Shallow Tunnel With Small Spacing Under Unsymmetrical Loadings

The shallow tunnel with small spacing under unsymmetrical loadings has the characteristics of shallow buried tunnel and bias tunnel at the same time,and the construction mechanics process is complex and changeable,which is often regarded as the key control project.Because of the particularity of shallow tunnel with small spacing under unsymmetrical loadings,it is necessary to analyze and summarize the mechanical characteristics of tunnel excavation in the construction process,control in what condition that the tunnel surrounding rock is under the most unfavorable state and where is the first occurrence of rock mass destruction,and take corresponding measures to ensure construction safety.The main contents of this paper are as follows:(1)Consulting relevant materials,deepening understanding and laying a theoretical foundation.By consulting relevant data,the theoretical understanding of the shallow tunnel with small spacing under unsymmetrical loadings is deepened.This paper mainly introduces the judgment method of shallow tunnel,the judgement method of bias tunnel,the judgment method of the tunnel with small spacing,the load calculation method of bias tunnel lining,and the load calculation method of shallow tunnel,which can deepen the understanding of the shallow tunnel with small spacing under unsymmetrical loadings and lay a theoretical foundation for the later numerical analysis.(2)Back analysis of mechanical parameters of surrounding rock of Dagejian tunnel.Combined with the typical section of the Dagejian tunnel,and analysis of the monitoring data,taking the displacement of the tunnel around the typical section as the known conditions of inverse analysis,software is developed for back analysis of rock parameters based on genetic algorithm by using Visual Basic 6 programming technology,the parameters of the elastic modulus,Poisson's ratio and friction angle ofthe Dagejian tunnel are inversed,and the optimized calculation parameters are obtained,which lays the foundation for the numerical analysis.(3)Numerical analysis of construction mechanics process of the shallow tunnel with small spacing under unsymmetrical loadings.Taking the Dagejian tunnel as the engineering background,numerical analysis mainly studies the mechanical effect of tunnel construction at different slope angles,construction mechanics effect of common construction method,analysis of construction process of bench method,surface subsidence law,and analysis of construction process of shallow bias tunnel with different slope and spacing,which provide a reference for similar research and engineering.(4)The comprehensive construction technology of shallow buried bias tunnel is put forward.On the basis of previous research,relying on the actual situation of tunnel engineering,from the aspects of the first face displacement control,surface settlement control,the temporary inverted arch and feet lock bolt etc.,the comprehensive construction technical system and stability control measures of shallow buried bias tunnel are summarized,which can provide reference and reference for similar projects.