Mechanical behaviors of cement concrete pavement structure under impact rolling load

In order to explain the mechanical behaviors of cement concrete pavement structure under impact rolling load, four typical loading positions were considered such as slab longitudinal side, slab transverse side, slab corner and slab center, the stress and deformation characteristics of pavement structures under the impact load of quadrilateral impact roller were studied based on 3D elastic-plastic dynamic finite element method.Analysis result indicates that the main reasons of old cement concrete pavement cracking in different cases are that the bottom of cement concrete pavement bears longitudinal flexural-tensile stress and transverse flexural-tensile stress, both base course and old slab appear flexural-tensile state in two directions, while subgrade is in three dimension compressive stage, and the effective influence depths are different in different cases.The vertical displacements of slab and influence depths are maximum when the load locates at slab corner, while the vertical displacements of slab are minimum and uniform when the load locates at slab center.Pavement slab is in longitudinal bending stage and easily forms transverse cracks when the load locates at slab center, while pavement slab is in transverse bending stage and easily forms longitudinal cracks when the load locates at slab side.So the cracking effect is a synthetic function of foundation stiffness, impact energy and impact location, it is reasonable that constructing scheme is chosen according to different road conditions.