Vibrations,Cumulative Deformation Characteristics And Design Method Of Highways Built In Soft Soil Area

The large-scale construction and rapid development of the highways can promote social progress and meet people’s growing demand for good travel.While on the other hand,the negative impact it brings can not be underestimated,such as the noise,pollution,ground vibration,and long-term settlement.At present,environmental vibration is one of the world’s public hazards,which has aroused widespread concern from all walks of life.In addition,the long-term settlement of highway foundation under the action of traffic loads will lead to adverse consequences such as bumping at the bridgehead and instability of the foundation,which may reduce passenger comfort,destroy the travel experience,and even cause accidents or threats to people’s lives and property.Therefore,this topic has great scientific value and practical significance.Acording to the above background,this paper studies the vibrations of the soft ground of the highway under moving traffic load in detail.And then,the cumulative deformation characteristics and desigh method of the soft ground are studied based on the measured data.The main research work is as follows:(1)A heavy truck-uneven pavement-saturated ground coupling model is established to study the dynamic responses of a saturated poroelastic half-space generated by the moving traffic.The ground is simulated as a fully saturated poroelastic half-space by Biot’s theory,the overlying pavement is modelled as a Kirchhoff thin plate,and the uneven pavement is assumed to be sinusoidal.The dynamic wheel-pavement force is gained through a linear Hertizian contact model.It is found that the dynamic wheel-pavement interaction force varies with the excitation frequency,and the stress and excess pore water pressure at different depths of the ground caused by the truck axle load and the wheel-pavement interaction force(dynamic load)are studied.Also,the total stress path and effective stress path of the subsoil induced by traffic load are analyzed.(2)A traffic load-uneven pavement-double-layered ground coupling model is established to study the influences of pavement irregularity on the ground vibration caused by moving high-speed traffic load.The lower soil layer was simulated as a fully saturated poroelastic half-space governed by Biot’s theory,and the upper one was simulated as elastic medium.The overlying pavement was simplified as a Kirchhoff thin plate,and the road surface irregularities are simulated by sine curves.The wheel-road dynamic load is obtained through the linear Hertizian contact model.The governing equations of this coupling model were solved by the Fourier transform and the time-domain results were got by applying the inverse fast Fourier transform.The displacement,vibration speed,acceleration,dynamic stress and the excess pore water pressure of the layered-ground caused by the axle load and dynamic load are studied.(3)In order to study the accumulative deformation characteristics of highways on soft soils,the equivalent time line model established based on the viscous-elastic-plastic theory is used to simulate the consolidation settlement and creep deformation of soft soils,and a cyclic cumulative strain model established in the laboratory experiment is used to simulate the traffic load induced ground settlement.Compared with the measured settlement data of the Shen-Jia-Hu highway in Zhejiang Province,it is verified that the equivalent time line model combined with the cyclic cumulative strain model can accurately predict the settlement of the soft ground soil during the construction period and after its opening to traffic.Afterwards,the influences of the traffic speed and the embankment surcharge on the various components of the road settlement are studied.(4)The highway built on soft soil often suffers from excessive settlement after traffic begins,which seriously affects its service performance and threatens passenger safety.This paper exploringly uses Mechanics-Empirical Design Method to predict the post-construction settlement of the highway built on soft ground caused by traffic moving loads to study its applicability in China.The dynamic response of the subsoil is calculated using the traffic load-pavement-ground dynamic response model established in the previous two chapters.The calculation results obtained by the Mechanics-Empirical Design Method are compared with the actual post-construction settlement data of several highways in different regions in China,and this verifies the applicability of the mechanics-empirical design method in China.In this paper,a series of theoretical models have been established,and the vibration response of highways under soft ground has been studied in detail.Based on this,the cumulative deformation characteristics and design methods of highways built in soft soil areas have been studied.This paper provides scientific guidance and theoretical basis on accurately evaluating the vibration of highways and predicting its cumulative deformation.