Lean Concrete Base Concrete Pavement Structure Design Study

The concrete pavement with lean concrete base (LCB) is a suited kind of pavement structure for heavy and over-heavy traffic. Because of its excellence, it has good future. To popularize it, its mechanical characteristics and method of structure design must be studied.First, the fatigue feature of lean concrete is studied by fatigue test in this paper. It is proved that lean concrete has better fatigue feature than semi-rigid materials. And two types of fatigue equations are put forward. According to them the fatigue stress coefficient of LCB for the concrete pavement structure and the structure coefficient of tension strength of LCB for the asphalt pavement structure are developed.The existing methods of structure design of concrete pavement with lean concrete base are analyzed, proving that the equivalent stiffness method is proper for calculating load stress but not for thermal stress.The load stress and the thermal stress of concrete pavement with lean concrete base are analyzed by three-dimensional finite element method, and the practical formulas of load stress under different axle load models and of thermal stress are get by regression method. The formula of axle load conversion in the standard has some problems, so respectively according to the corresponding formulas of load stress and fatigue equations of concrete pavement and LCB, the different formulas of axle load conversion and fatigue stress coefficients are put forward.At last a probabilistic method of structure design of concrete pavement with LCB is advanced.