Research on cracking and mechanical responses of semi-rigid base under falling weight impact

Abstract

Disadvantages of semi-rigid materials bring a significant challenge to the maintenance of the semi-rigid base pavement. The micro-cracking treatment employs the falling weight to break the semi-rigid base into interlocking blocks to create a new base material to regenerate the old base. To study the micro-cracking mechanism, the cracking patterns and mechanical responses of the semi-rigid base under different types of falling weights and drop heights were obtained in field tests. The DEM-FDM coupling model was established to investigate the cracking distribution further. The results showed that as the impact contact area of the falling weight decreases, the depth of the groove progressively deepens, and the resilient modulus of the semi-rigid base decreases. Besides, the flat-bottomed falling weight produced the highest compressive stress, while the big convex points falling weight caused the most vertical displacement. Combined with simulation analysis, the flat-bottomed falling weight almost exclusively caused shear cracking on the contact edge. The small convex points falling weight mainly generated the shear cracking on the surface, and the big convex points falling weight induced more extensive tensile cracking within the semi-rigid base. Therefore, the big convex points falling weight is more recommended for micro-cracking treatment, which creates a greater cracking degree in semi-rigid base and is conducive to breaking the semi-rigid base into interlocking small blocks.