Ultimate Bearing Capacity Analysis And Research Of Portland Cement Concrete Pavement Structures

With the development of highway in our country, road transportation overloading becomes widespread and serious. As one of the main structures of highway, many of cement concrete pavements are distressed seriously in the early of life, and the road life is significantly shortened; also the road capacity, traffic safety and investment returns are seriously affected. When the load stress and temperature stress of road slabs combine in a disadvantaged state, pavment structures may be distressed when a large axle load loading one time, the fatigue of pavment structures becomes insignificant. Procedures to analyze ultimate bearing capacity of pavement structures have not been included in existing specifications for design of cement concrete pavements in the world. Therefore, studies on analysis and design method of cement concrete pavements in ultimate states based on actual composition of road traffic and temperature conditions become more important.In this paper,the traffic surveys and analysis of typical heavy-load road were performed firstly; Also the characteristics of traffic, load and distribution of axle load were studied. The deficiencies in the calculation method of surface equivalent modulus of foundation in present specification of cement concrete pavements design for highway were analyzed. Based on the elastic multi-layer theory and principles of displacement equivalence, and a great amount of computing data, a calculation method was established. Then, mechanical responses of pavement structures were analyzed with elasticity theory, based on actually applied pattern of heavy loading, analysis method of ultimate bearing capacity of pavement structures was proposed, and the factors affecting ultimate bearing capacity were analyzed also, which provided a theoretical basis for the restriction of alex load. Again, the probabilities of vehicle axle load and temperature gradient were studied; the design method of cement concrete pavements considering ultimate bearing capacity was proposed, and the typical pavement structures meeting the levels of axle load limits were developed also. Finally, in response to the cavities beneath road slabs, 3D finite element analyses of pavment structures were conducted, the impacts on bearing capacity and life of pavements caused by cavities were analyzed, the reasons of early distresses were revealed; Also, in the aspects of pavement materials and structures, the measures and methods to prevent cavities were explored.