Abstract:A series of experiments to investigate the reinforced mechanism of transverse and longitudinal ribs were conducted with newly developed individual rib pullout devices under various normal load and pullout velocity. By analyzing experimental data, some conclusions are made that the frictional resistance of longitudinal ribs rapidly increases in early time of the pullout test, which is enhanced with the increase of effective stress but not with pullout velocity. However, passive resistance generated by transverse ribs increases more slowly than frictional resistance, and certain displacement is necessary to reach its maximum. With the increase of effective stress and pullout velocity, the failure mechanism of passive resistance is changed from the punching failure mechanism to general shear failure mechanism.