| In recent years,the demand for the construction of long and large highway tunnels has been increasing and there are still many areas worthy of in-depth research in the field of tunnel composite pavement design methods.Due to the small volume and low proportion of the tunnel pavement,no specific regulations have been issued.The tunnel composite pavement and ordinary asphalt pavement and cement concrete pavement are quite different in structural combination,load form,subgrade modulus,service environment,etc.Therefore,it is necessary to carry out in-depth study on some contents in the design method of tunnel composite pavement structure.In this paper,based on the monitoring data obtained by the buried temperature sensor in the East Tianshan Tunnel,the numerical simulation of the tunnel composite pavement temperature field is carried out,and the characteristics of the tunnel composite pavement temperature field are summarized.Using PYTHON to assist modeling,through numerical simulation and regression analysis,the axle load response formula suitable for the tunnel composite pavement structure is obtained,and the axle load spectrum conversion and typical structural fatigue axle calculation analysis are carried out.Based on the typical tunnel composite pavement structure with thinned base,numerical simulation analysis considering voiding and transfer of tranvers joint was conducted to explore the structural durability under special circumstances.First,temperature sensors were buried in the East Tianshan Tunnel to monitor and analyze the temperature change.Determine the finite element model structure according to the typical tunnel pavement structure combination;analyze the tunnel special environment and determine the relevant boundary conditions.Based on the ABAQUS platform for numerical simulation,according to the simulation results,the necessity of fatigue damage analysis and cumulative damage method and the necessity of temperature stress calculation of cement concrete slab are analyzed.Second,write PYTHON scripts to establish a dynamic response finite element model.Orthogonal experiments are designed to establish a multi-operating model and perform numerical simulation.SPSS was used to fit the regression strain of the bottom tensile strain of the asphalt layer,the maximum shear stress of the asphalt layer,and the bottom tensile stress of the cement concrete slab respectively.The conversion formula of the axle load spectrum of the compound pavement structure of the tunnel is proposed,and the fatigue axle analysis and calculation are carried out.Considering the economy,on the basis of the typical structure,explore the influence of the thickness change of each structural layer and the selection of different modulus asphalt layers on the life of the pavement structure.Finally,the finite element model and parameters of voiding and transverse joints are determined,and the numerical simulation and analysis are carried out for the typical structure considering the two aspects of plate corner and plate edge voiding.The fatigue life of the structural response under the most unfavorable load condition with the size and position of the void is explored separately.Considering the condition of lateral joint load transfer,explore the influence of the change of steel bar diameter and spacing parameters on the two voiding situations.The fatigue life of typical structures under void conditions is evaluated,and the applicability of the setting of the transverse joint force transmission rod under the two void conditions is obtained.The results of this paper enrich the researches on the axle load spectrum conversion,fatigue calculation and analysis,and void simulation of the tunnel composite pavement structure,and provide references for the study of the design method of the tunnel composite pavement structure. |
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