| Around all over the China,there is about 417.1 × 104 square kilometers of cold area,accounting for 43.5% of land in China.Most of these places are located in the west,northeast and other cold,high-altitude area.There,however,the underdeveloped economy condition and high traffic demand always produced the main conflicts.Obviously,this space will be regarded as a vital point of traffic development,but with the influence of freeze-thaw cycles and the stress of climate,the quality of road construction has been seriously affected by the temperature.In the perspective of the quality of cold road construction,this paper analyzed the features of road disease in some typical cold areas.Meanwhile,the paper depicted the influence of low temperature and the cold climate on road construction.In that case,the key factors affecting the quality of road construction were determined by the indoor experiment,and then the corresponding temperature standard was made up well,which provides the basis for the quality control of road construction.Results demonstrated that the vertical cracking in the cold area is generally considered as the disease resulted from the subgrade melting,and in wider sense,the longitudinal,especially the continuous longitudinal,has developed rapidly in the recent years,whose width and length has rocketed to peak during the periods about 1-2years.In this aspect,the general irrigation and other curing measures has few impact on it.In details,the diseases of rut or embracing are relatively rare,accounting for about 6% of all investigated diseases.Meanwhile,the frequent braking and subsidence of vehicle is a main cause of such diseases,and approximately 70 % of the settlement disease will cause the great additional stress on the road,which will result in serious road disease.The effects of short work duration,great temperature difference all will resulting in the fact that they need to conduct ??the road construction at the temperature of 10 ℃,or even below 0 ℃.In short,the low temperature compaction will deduce the effective rolling time,and increase the complexity of mixed material compaction.It also contributed to the insufficiency of the mixture compaction and various diseases of the road.The indoor experiment revealed that the effect of temperature on the mixture’s compaction degree was more than that of the road thickness on the forming density.On the condition of low temperature,the temperature of the structural layer is much higher than that of the thin layer.Therefore,in that case,the rolling temperature plays a main role in the final step.In details,when the molding temperature is lower than 120 ℃,the maximum of mixture compaction could just reach98.6% no matter how much the compaction work has increased;when the molding temperature turned below 100 ℃,the maximum of mixture compaction will hardly reach to96% no matter how the compaction work increased.In other words,the standards of current highway engineering and technical testing kept around 98%,mainly on high-speed and first-class road surface compaction.This standard level turned down to 96% at least for the secondary road and general municipal road.Therefore,the paper select the level of 120 ℃and 100 ℃ as the minimum controlled temperature of the highway and secondary road compaction,and put forward the effective rolling time.The paper selected the Zhizhi multi-highway,in Yushu,Qinghai,as the sample of test for verification,compaction,permeability and anti-skidding.In short,the results revealed that the temperature control index designed by the researcher could guarantee the quality of road construction in cold area. |
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