Optimization Of Diameter-thickness Ratio Of Highway FRPM Pipe Culvert Based On Thickness Of Pipe Top Covering Soil

In recent years,with the rapid development of highway traffic construction in China,and the number of culverts has also increased.At present,most of the pipes used in highway culverts have appeared quality problems.Therefore,this paper proposes to replace the existing pipe with glass fiber reinforced plastic sand pipe.However,due to the lack of micro-mechanical analysis of highway FRPM pipe culverts,the corresponding design standards are lacking in the design process.In order to ensure the safety of the pipeline structure,the pipes with large safety margin are usually selected,which increases the engineering cost.Therefore,this paper combines field test with numerical simulation to optimize the diameter-thickness ratio of highway glass fiber reinforced plastic sand pipe based on the thickness of pipe top covering soil under different working conditions.The main research results include the following aspects:(1)Compressive and tensile properties of glass fiber reinforced plastic sand pipes with different wall thickness were tested,the circumferential and axial tensile and compressive strength values of the pipe under different wall thickness were obtained.(2)Field tests of highway FRPM culverts under different vehicle loads were carried out to measure the stress and deformation of the pipe.The test results show that as the load level increases,the circumferential and axial strains of the pipe also become larger,and the circumferential strain and axial strain of the pipe are symmetrically distributed about the central axis of the pipe;The relative displacement value is slightly larger than the horizontal relative displacement value.These provide reference data to verify the accuracy of numerical analysis model.(3)When the pavement structure is the same,the influence of pipe inner diameter,pipe top soil thickness and vehicle load on the mechanical properties of highway FRPM culvert is analyzed by using finite element software ABAQUS.The numerical results show that when the load and pipe top soil thickness are constant,the maximum tensile and compressive stresses of pipeline increase with the increase of pipe inner diameter.And the horizontal and radial relative deformation increased significantly.When the load and diameter of the pipe are fixed,the relative radial deformation of the pipe and the maximum tensile and compressive stresses increase with the increase of the thickness of pipe top covering.When the thickness of pipe top covering and diameter of pipe are fixed,the maximum tensile and compressive stresses and the relative radial deformation of the pipeline increase obviously under the action of double vehicle loads.(4)Based on the analysis of the maximum tensile stress at the bottom of the pavement base layer and the stress and deformation of the pipeline under different wall thickness,the optimum diameter-thickness ratio range of highway culvert FRPM pipe based on the thickness of pipe top covering soil under different working conditions is obtained.It provides a theoretical basis for the design of highway glass fiber reinforced plastic culvert.(5)A device for protecting pipelines in highway FRPM culvert construction has been developed,which provides a new idea for highway FRPM culvert construction.Finally,based on practical engineering,the economic analysis of optimized FRPM sand pipe has been carried out.