Influence Of Heavy Vehicle Dynamic Load On Stress And Settlement Deformation Of Expressway Widening Project

The rapid growth of traffic volume has made the early-established expressway need to be widened and rebuilt.In the process of widening and rebuilding the expressway,the uneven settlement between the old and new roadbed has always been a difficult problem to restrict the quality of highway engineering.In recent years,with the development of the direction of the traffic vehicles toward high speed and heavy load,the influence of vehicle load on the differential settlement of new and old roadbeds has become more apparent.In this paper,the dynamic load generated by heavy-duty vehicles on uneven road surface was simulated,the dynamic response of the road surface was expanded under dynamic load,and the influence of the force and settlement between the old and new roadbeds was studied.The following conclusions are obtained:1.According to the traffic investigation and analysis of Tangjin Expressway,the traffic composition characteristics and traffic volume are obtained.2.A seven-degree-of-freedom(1+1+5)road surface coupling dynamics model was established for a four-axle heavy-duty vehicle,and two double-degree-of-freedom and one three-degree-of-freedom vehicle vibration model were simplified and decomposed.The mathematical calculation is performed by Matlab.The software programming program calculates the maximum dynamic load of different wheels with the change of vehicle speed,and obtains the variation of the maximum dynamic load of the most representative trailer rear wheel with wavelength,amplitude and load.3.Using the large-scale finite element software ABAQUS,establish a three-dimensional pavement structure model,and obtain the dynamic response law(dynamic strain,dynamic stress,shear stress)of the upper layer SMA,the middle layer AC-20,the lower layer ATB,the upper base layer GM,the lower base layer CTB and the fill under the influence of the dynamic load of the heavy-duty vehicle.4.By establishing different numerical models of new and old roadbed widening under different widths,subgrade heights and fills,the effects of different widening forms on the differential settlement of new and old roadbeds,the additional stress on the base and the additional stress of each fill layer are obtained.The subgrade model applies cyclic vehicle dynamic load to obtain the influence of heavy-duty vehicles and their dynamic loads on differential settlement of new and old subgrade under different widening forms.5.By establishing a horizontal solid reinforcement(geogrid)and vertical reinforcement(cement mixing pile)composite foundation treatment model,the establishment of geogrid and cement mixing pile can effectively reduce the differential settlement between the old and new subgrade.The material parameters of the grid and cement mixing piles are crucial to the stability of the subgrade.The selection of effective material parameters can better control the differential settlement between the old and new subgrade.