3-D FEM analysis of pavement crack at cut to fill location of subgrade

In order to prevent pavement cracking at cut to fill location of subgrade, the treatment mechanism and proper layout of geogrid were studied by 3-D finite element method(FEM), subgrade FEM models with various lengths of geogrid and various number of geogrid layers were built, a model without geogrid was also built for comparison, the vertical displacement, longitudinal stain and stress of pavement surface and geogrid stain and stress were analyzed. Geogrid in subgrade reduces the vertical displacement of pavement surface, scatters the concentrated tensile strain and stress at cut to fill location. The maximum geogrid stress and strain of all models are below 1 MPa and 0.3% respectively. For one layer case and the bottom geogrid for multilayer cases, geogrid stress and strain are decreased gradually from cut to fill side. In the other layers, geogrid stress and strain at cut side near cut to fill location are maximum. It is discovered that geogrid eliminate or postpone the pavement transverse cracking, for one layer case, geogrid should be longer in cut side than in the fill side, the bottom geogrid should be longer in cut side than in fill side, and the others should be laid symmetrically for multilayer cases.