Mechanical Analysis And Numerical Simulation In The Construction Of Highway Tunnel

Although the construction of highway tunnel engineering speed rapidly,the highway tunnel related theory and the construction technology research are still not enough in-depth.This paper is based on engineering examples[1]to study the working mechanism of the primary support and secondary lining in tunnel.Under the condition of changing the size of the secondary lining stiffness,respectively study the secondary lining thickness,elastic modulus,Poisson's ratio,the influence of different depth of the tunnel and changing the distance on the supporting system.Using the finite element software FLAC[2]for the tunnel excavation supporting to do the numerical analysis in detail,under different working conditions,understand the internal force and deformation of tunnel support system,around the tunnel by two Chambers exist influence each other.The tunnel vault,arch waist and force in the central part of the inverted arch are more disadvantageous position,when the design to do locally enhanced,also should pay attention to during the construction of support.Through the analysis of the monitoring variables,The maximum unbalanced force eventually become convergence,around the tunnel arch displacement of supporting system is stable.When the supporting system of the secondary lining stiffness change with the increase of thickness of secondary lining,in the vault,arch waist and the foot of in the arch,the surrounding rock stress of secondary lining increases linearly,but when the thickness of650 mm increase rate slowed.And stress changes in the secondary lining of spandrel sizes and regularity is not strong.When supporting system of the secondary lining stiffness changes with the increase of elastic modulus,the waist place and spandrel arch compressive stress of the secondary lining.It is basic linear change.And it is no impact on the arch,arch feet.To change the size of the Poisson's ratio has no effect on stress of the secondary lining is basically.When the secondary lining stiffness increased,not necessarily will make the surrounding rock ofsecondary lining pressure increases.Because the stress of the composite lining is more complicated,at this time,continue to analyze the concrete factors influencing the stiffness size of the secondary lining.With the increase of tunnel buried depth,gravity stress of surrounding rock increases,the early support of surrounding rock in tunnel support system pressure goes up,this is consistent with our subjective feeling,and the rate of increase faster and faster,the stress of the secondary lining basically remain unchanged,reflect the primary support system of tunnel is the main load-bearing structure.With the increase of the distance between two tunnels,Right tunnel to reduce the influence of left tunnel,supporting system of left the tunnel stress smaller,fade out the mutual influence between the two tunnels.