The Research On Technologies’ System For Intermediate-heavy Maintenance Of Asphalt Pavement Of Highway

The asphalt pavement is the main form of highway adopted by our country.With highways constructed in the early state is reaching their twilight year,many of them come into the medium and big maintenance period successively.Doing medium and big maintenance to the asphalt pavement of highways has become a crucial topic.More and more highways are coming to the medium and big maintenance’s period,this project has been an huge and onerous task extraordinarily.However,the proposal of the medium and big maintenance lacks theoretical basis.The release of this project is so subjective that it doesn’t have a complete technical system about the medium and big maintenance nor does it has designing and construction specifications which aims at medium and big maintenance project specifically.In this case,the study on the medium and big maintenance technical system to the highway’s asphalt pavement is of great significance to improve the medium and big maintenance techniques as well as to enhance the engineering technique and management levels of the the medium and big maintenance.Firstly,the paper makes some deep researches to the typical internal highways on the traffic volumes,axle load composition,structures,problem mechanism,types and the inspection data to the technical condition of the pavement;defines the typical structure of the medium and big maintenance to the highway;studies the influences that the sample size and monitoring period of the pavement monitoring data on the serviceability of pavement;introduces the indexes to the reliability of pavement structures;ascertains the timing of the medium and big maintenance according to the level of the reliability of pavement structure.This paper divides the level of the reliability into 5 degrees:superior,good,medium,inferior and bad.This can be used for the gist of deciding the timing of the medium and big maintenance to the highway.Secondly,the paper uses shakedown theory to analyze the various influences that the pavement structure index of the typical structure of the medium and big maintenance to the highway has on ultimate load on the condition of different thickness of asphalt layer and layer modulus;to set up the yield criteria to the material of the pavement’s big maintenance.And this paper also uses ANSYS to simulate shakedown limit load of the structure of the big maintenance to highways under the conditions of the interaction of cyclic loading when the plastic failure is achieved.From the overall perspective,the effects that the thickness of pavement structure layer has more dramatic than the modulus on the shakedown limit load of the medium and big maintenance structure;using old milling material as medium and big maintenance structure layer has more good effects than other structure layers on the shakedown limit load.There are mainly three modes of damagement to highways: fatigue cracking,the rut and PSSI.The dominant factor that causes fatigue cracking is the tensile stress of the base of the structural layer is bigger than the tensile stress that the material can hold.The factor that causes the rut is the shearing strength of the material is so big that it makes the material deform.PSSI is a main index to reflect the bearing capacity of pavement’s structure.Three design controlling indexes are generated on the basis of the three factors above,which are surface deflection,the tensile stress of the base of the structural layer and the maximum shearing stress between the layers.Based on the response surface,the paper analyzes the influences that the design indexes of the asphalt pavement of highway on the structure.The structure can be optimized by making full use of the original structure.Besides,by matching the design parameters and the design indexes of the typical structure of the medium and big maintenance,the response surface can be made and the regression equation can be optimized.At last,the continuity problem of the construction layers is studied,the construction technology―asynchronous continuous paving is generated.Some deep researches which are suitable to the construction technology of the highway are made.By analyzing the effect of road paving and its economic effects,the paper shows that asynchronous continuous paving can distribute builders,technology and material,extend the useful life of the pavement and notably decrease the costs of cycle use.