Research On Relation Of Contraction Joint Transferring System And Structural Breakage Of Cement Concrete Pavement In Seasonal Frozen Region

Cement concrete pavements are the main pavement form of hignway, possessing excellence of strong carrying capacity,stabilization and durability,fine sight in night,protecting environment,without track,process and bump, applied abroad in our country after 20 century 80 years, construct stabilization and durability,well function cement concrete pavement possessing active effection on exerting superiority of plenty cement resource, ensuring transportation and persistence development of district economy. Under circumstance of high latitude,low altitude seasonally frozen area in Heilongjiang province. Cement concrete pavements appeared traverse and longitudinal Crack,corner breakage,faulted joint disease. Planeness,comfort decline severity, common usage life lack 50% of design norm life. Pavement structural disease exist long,bring great difficulty in repair and maintain, affect function and longevity of pavement,became the technic difficulty of development application of concrete pavements.Enhance load transferring ability of contraction joint transferring system are important technic measure of maintain load transferring between slab,enhance carrying capacity of pavement,reduce structural breakage,improve bearing condition of base and slab,prolong longevity of pavement. Because of multiple factor affected, though adding understanding importance of joint transferring system, relative research and application always lag behind in our country. The article based on analyse and contrast of difference in structure design of common cement concrete pavement, by the investigation and observation of pavement structural disease, aim at appearance shape of highway cement concrete pavement structural crack in Heilongjiang province, apply finite element analysis method of joint cement concrete pavement and Miner linear accumulative damnify theory, research influence mode of joint load transferring to cement pavement structural breakage, discussion of optimize joint dowel bar load transferring system.By analyse Influence factor of different means considering cement pavement structure design, definite difference disposal mode of pavement joint factor in cement concrete pavement structure design method of nationnal and international, indicate that consideration of cement pavement traverse joint load transferring factor in national structure design method only limit to fixing critical load position when pavement stress compution, but fatigue crack controled by this critical load position have obvious differenence with ubiquitous longitude crack.Research indicate, in cement pavement structural breakage,traverse and longitude crack are main breakage form that appeared earlier,ubiquitous,most proportion. Crash slab also developed by the two crack. If count in relative crash slab and corner breakage, total disease proportion reach to 96%. Though disease reason of structural crack is complicated, but common point is relate to load transferring condition of pavement joint(mostly traverse joint); in the traverse joint investigation of cement pavement fine slab, joint load transferring ability deficient is 6.56%, joint load transferring in fine condition is 93.44%. Indicate appearance of cement concrete pavement structure disease have intimate relation with joint load transferring condition in Heilongjiang province. Compution and observation indicate:Westergaard parse formulation^ EverFE finite element analysis method,structural stress compution method of highway cement concrete pavement in our country have benign corresponding and accordance.The article analysed influence factor and possible appearance shape of cement pavement fatigue crack in Heilongjiang province. By test and observation, using Miner linear accumulative damnify theory and finite element analysis programm to analyse load fatigue stress of cement pavement.The result manifest that joint breadth changed between 0-3.5mm of cement pavement in Heilongjiang province, joint load transferring ability and durability of aggregate interlock mode reduced prompt along with increase of joint breadth.After setting joint dowel bar, change of joint breadth influence on joint load transferring ability and durability reduced greatly, joint load transferring coefficient maintain stable at a high level. When setting dowel bar, maximal tensile stress of slab bottom reduced, influence extent of joint breadth change suffered less; tensile stress of slab bottom bigger of joint without dowel bar,easily influenced by joint breadth change. Dowel bar load transferring system strengthen bearing condition of pavement slab, in favor of reducing different subsidence of border slab, alleviate vehicle shake caused by faulted joint, maitain planess of pavement and travelling comfort.According to vehicle trace traverse distribution and joint load transferring character, we proceed analysis of fatigue stress. Indicate that Highway cement pavement have likelihood of longitudinal crack and traverse crack, but because of fatigue degree at traverse joint edge bigger than traverse Section of Longitudinal Joint center. For cement concrete pavement, likelihood of longitudinal crack bigger than traverse crack. Apply dowel bar load transferring system may reduce load fatigue degree of joint edge, fatigue degree peak value reduce extent between 15.3-25.0%. Apply dowel bar load transferring system can reduce and delay appearance possibility and time of longitudinal fatigue crack.The article using Bradbury dowel bar computation formulation,Visual Basic 6.0 programme and finite element analysis programm EverFE, analyse length, diameter and setting space of dowel bar, and influence on tensile stress of slab bottom and joint load transferring ability. Research indicate when the ratio of length and diameter is 18.0, requisite rvailability roefficient of dowel bar load transferring system is least, joint load transferring system efficiency is higher; suggested that when thickness of pavement≤24cm, dowel bar setting space take 30cm; when thickness of pavement>24cm, dowel bar setting space take 40cm, may reduce 27% dosage of dowel bar steel.The article research content have active effection on reducing structural breakage of cement pavement, understand and appraise structural durability and working condition of cement pavement; in favor of reducing highway constuction and transport cycle cost, have important social meaning and benign social economical benefit.