Research On Widening And Splicing Technology Of Old Cement Pavement On Guangxi Expressway

In order to improve traffic operation ability and driving safety,Guangxi Coastal Expressway and Liuzhou Nanning Expressway extend the original lane to eight lanes,Because Guangxi is located in the tropical monsoon climate and the southern subtropical monsoon climate zone,cement concrete pavement is used in old pavement.The old road surface of guangxi coastal expressway is seriously damaged,during the expansion,all the original pavement concrete slab was excavated,the expansion is relatively simple.After a certain period of service,the original road surface of liuan expressway has been transformed into "white and black",the "white and black" pavement structure is used in the expansion,so it is faced with the research of the new and old pavement structure layer splicing technology and so on.For such a large-scale reconstruction of the old cement pavement expansion project is relatively rare in the country,less experience for reference,Therefore,it is necessary to make a special study on the widening and splicing technology of the old cement concrete pavement in Guangxi expressway.The article mainly takes the reconstruction and expansion project of Guangxi Liuzhou to Nanning expressway as the research object,on the basis of the analysis and evaluation of the original pavement condition,Through the choice of road widening method and new pavement structure scheme,the mechanical effects of different splicing methods on the new and old pavement,change of load position and the mechanical effects of glass fiber grille on the widening and splicing of the old cement pavement are studied,some suggestions on the design of new and old pavement widening and splicing are also put forward.The research conclusions are as follows:1)Statistical analysis of the test results of the original pavement structure shows that the "white and black" pavement meets the design requirements of the extension years after asphalt overlay.Relevant evaluation and disease disposal measures are put forward for the original pavement.2)The different types new pavement structure schemes and different widening ways are studied,according to the actual situation of Liunan Expressway,Finally,it is decided that the two sides should be widened as a whole,partial one-sided or separate widening scheme is adopted locally,the semi-rigid base asphalt pavement is adopted for the new pavement structure.3)Stress analysis of old cement pavements with different splicing methods shows that the stress concentration on the SMA-13 layer is more likely to happen When the oldand new pavement is not overlapped.The overlap is compared to the non lap,the stress of the base is larger than that of the non lap joint,and the stress distribution of the splicing pavement structure is more uniform,which Improve the overall bearing loading capacity of the pavement.4)Analyzing the mechanical influence of load location change on the widening pavement of old cement,it is show that the most unfavorable location of new and old pavement is located in the-60 cm to 60 cm area of concrete slab joint.Combined with the mechanical analysis of the old cement concrete pavement with different splicing methods,the width of the new and old pavement splicing is the best for 140 cm.5)The influence study of adding glass fiber grille on the mechanical effect of widening pavement structure shows that: The addition of glass fiber grille improves the tensile and shear capacity of the pavement structure,and makes the stress of the splicing pavement structure layer distribution more uniform,restraining the emergence and development of pavement cracks effectively.The glass fiber grating has three layers and the laying width of 1.5m is the best.6)On the basis of the analysis force on the new and old pavement splicing methods and the influence of the glass fiber grille on the structure of the spliced pavement,the design scheme of the widening and splicing of the old and new pavement on the old cement concrete pavement of the Liu Nan expressway is proposed,some suggestions are also put forward for the construction requirements of fiberglass grille.