Research On Mechanic Response Of Jointed Pavement Structure In High Way Widening Project

Reconstruction of existing highway is an important way to improve the capacity of highway network. In the whole state, a large number of highways have been rebuilt to meet the need of a sharp increase in traffic volume during the past decade. And the relative research was concentrated on how to widen the old subgrade and control the discrepant sedimentation between old subgrade and widened new subgrade. As to the new-old pavement structure jointing, there is merely any systemic study base on theoretical or numerical method, most of which is some experiential principles or advices in construction technique.So it is of great importance to study the mechanism characteristic and design method of jointed pavement structure. The main content studied in this dissertation is as follow.(1) The three-dimension finite element model was established to demonstrate the mechanic of jointed pavement structure. A series of method was employed to simulate the mechanic response of jointed pavement structure. Then some suggestions for design were proposed.(2) Analyzed the factors that affect the jointed pavement structure mechanical response, include load location, pavement layer material modulus, interface contact condition, et. To control the shear stress increase in 10%, the difference between new pavement layer and old pavement layer should be limited to 30%～40%. Which can be used in design and making standard about old pavement reservation and reuse.(3) Interface cohesive stiffness between old base layer and new base layer was studied through 3D interface delimitation model, found out the characteristic how required cohesive stiffness between the two base layers was affected by the behavior of interface binder.(4) By analyze the implication of sidestep in the joint part between old pavement structure and new pavement structure, the optimum design was proposed about the formation and dimension. It's advised that surface layer step-width should be more than 20cm, and the optimum base layer step-width is 40cm～60cm.(5) Through the analysis of additional stress in the pavement caused by discrepant sedimentation considering the stress relaxation effect of asphalt surface layer, indicated the special cracking mode of jointed pavement structure, as the tensile cracking at the top of the base layer where the tensile stress comes to a maximum value first than the surface layer. When surface layer modulus is less than about 40%, the tensile stress in base layer is bigger than the tensile stress in surface layer.