Research On Damage Diagnosis And Maintenance Decision Of Asphalt Pavement In Expressway

In recent years,with the rapid and deepening development of expressway construction process in our country,service quality requirements of the expressway as an important transport infrastructure of transportation also got rapid development.Providing good pavement service decision becomes the Key point of maintenance and management on expressway.How to implement the reasonably practicable mended pavement and accurate pavement disease diagnosis and scientific and effective pavement maintenance decision becomes the focus of the highway maintenance wor K in the expressway operation.In this paper,based on the research of Guangxi LB expressway asphalt pavement maintenance management,LB highway was opened at the end of 2005,So far,it has been running for 10 years.At present,by analysising the PQI and PCI which are the pavement condition index are in good condition.The maintenance and management of LB expressway has a good reference significance.LB highway pavement performance as a whole is on the decline as it ages,Through analyzing the pavement field investigation,the original pavement produce Four Kinds of typical pavement diseases: the longitudinal cracK,rutting,potholes and blocK ~ layered rocK.To resume the pavement performance of LB expressway,improve the road service level,maKe effective utilize maintenance costs,and put forward scientific and effective maintenance measures have practical significance.Pavement structure and pavement diseases of LB expressway pavement is analyzed,conclude that the main four types of typical pavement diseases: concrete pavement cracKs of embanKment,rutting,blocK~layered rocKs and the pits and holes of concrete pavement.First of all,by analyzing four Kinds road section of typical diseases,which are the selection of pavement in good condition,serious ruttings,bloc K~layered rocKs and pits and holes.pavement evaluation is made by testing the drilling core sample from a certain expressway and rut depth detecting methods,pavement water penetration test,FWD testing and laser deflection testing,then in combination with indoor test.it is concluded that early pavement disease may be caused by the reason that top layer porosity is too big,leading to water damage,resulting in holes.At the top of Water stability roadbed from 80% core samples is loose,and formating about 20~35 mm soft interlayer,then damaging at the fatigue limit under the influence of under dynamic load,eventually causing the road blocK.Asphalt layer shear strength is insufficient and the second phase of the project construction maKes the surface of the surface glue layer asphalt too much cause severe rutting phenomenon.Phenomenon of early fatigue cracKs and tracKs are mainly led by insufficient of the shear strength between asphalt pavement layers and ma King too much tacKy surface bitumen of the intermediate surface in the second phase of the engineering construction.Then,gathering traffic volume these years,section traffic volume survey of up and down the road investigated,and vehicle axle load and overload conditions ware detected,equivalent axles ware computed.At the same time,the cumulative numbers of equivalent tandard axle loads ware analyzed and calculated in the indoor,pavement structural strength was evaluated,pavement mechanics model is established,load stress of pavement structure layer was calculated.Fatigue damages of old pavement and fatigue lives time of the overlay reinforced structure ware analyzed.Based on the above,this paper can draw a conclusion that incompact in top and below of pavement is contained in upper and lower cement stabilized macadam layer of disease pavement section,fatigue damage has reached to 68%,completely smooth fatigue damage has reached 28%,fatigue damage of good bonding between interlayer Pavement has reached to 9.2%,reinforced repair of lumping area into consideration should be taKen.Lastly,based on pavement detection and evaluation and result,effective and feasible pavement maintainance measures that include(1)when PCI is greater than 90 and SSI1 is greater than 0.78,highway maintenance department shoud be in Keeping in good maintenance,(2)when PCI is less than 90 and SSI1 is less than 0.78,the measure of reinforcing repair of small area shoud be taKen,(3)water layer bottom wre loosely,and between in fluctuation layer is formed between 20 to 35 mm thicK soft interlayers,and mpact load stress of Water layer bottom ware too much,after years of driving,roadbeds have been destructed the fatigue strength after strength reached to fatigue strength,the action of excavating damaged pavement and rebuilding asphalt layer should be ta Ken.