Analysis Method And Experimental Study Of Tunnel Pavement Structure Based On Non-zero Strain Moment Theory

The surrounding rock strength of the tunnel roadbed is high,and the relative stiffness radius of the cement concrete pavement slab exceeds the scope of application of the current design theory and method,which leads to the inconsistency between the mechanical calculation results and the actual situation,and affects the design analysis results and service life of the tunnel pavement.It is necessary to modify the current calculation theory and method.At present,it is very difficult to verify the theory of preparing large-scale cement concrete test slabs,and there is a lack of an effective and convenient test method to verify the theory.Therefore,this study carried out the tunnel pavement structure analysis method and experimental research.The main research contents and results are as follows:(1)According to the theory of non-zero moment elasticity,the expressions of the bending stiffness and the moment of inertia of the beam are modified.The basic equation of the elastic foundation plate is re-derived by replacing the elastic foundation plate with the infinite beam on the orthogonal elastic foundation.The calculation formula of the load stress of the elastic foundation plate under load in the plate is proposed,and the classical thin plate theory is compared with the existing experimental data.The results show that the calculation results of the new theoretical formula are closer to the measured results and can be used for the analysis of tunnel pavement structure.(2)The test method of cement concrete double-slab is proposed.This method is used to study the influence of different base stiffness and panel strength on the bearing capacity,deflection value and energy dissipation level of the double-layer test plate.The mechanical model of the cement concrete test plate is established by using the method of orthogonal elastic foundation finite long beam instead of elastic foundation plate,and the mechanical model of the test plate is compared and verified by the test data.The results show that the greater the stiffness of the base layer,the greater the ultimate bearing capacity of the pavement slab,and the smaller the ultimate deflection value;the double-layer plate test method can verify the validity of the mechanical model of the test plate and prove the correctness of the non-zero strain moment theory.(3)Taking the typical tunnel pavement structure as an example,the influence of subgrade reaction coefficient,leveling layer thickness,surface layer thickness and vehicle axle load on the load stress of tunnel pavement is studied by using the new theoretical formula.The results show that under the same axle load,the greater the subgrade reaction coefficient,the greater the shear stress of the leveling layer and the surface layer,and the smaller the deflection value of the leveling layer and the surface layer.The shear stress and deflection of the leveling layer decrease with the increase of the thickness of the leveling layer.The greater the thickness of the surface layer,the smaller the shear stress of the surface layer.Under the same road condition,the greater the axle load,the greater the shear stress and deflection value of the leveling layer and the surface layer,and the excessive axle load can easily make the shear stress of the leveling layer increase sharply to the failure strength and fracture failure occurs.In order to avoid the early failure of the leveling layer,the strength of the concrete or the thickness of the leveling layer should be appropriately increased.