Post-settlement of rockfill in silty soil reinforced by explosive replacement method

The explosive replacement method is a highly effective reinforcement method for deep silty soil layers, which leads to the post-explosion settlement of integral rockfill. In this paper, several chamber tests were carried out to investigate the effect of different blast equivalents and depths of charge on the settlement behaviour of the rockfill. Blasting caused a reduction in undrained shear strength (Su), but this was eventually largely restored, followed by a gradual dissipation. The highest settlements were observed for the integral rockfill at a 20 cm positioning depth of the charge, with increases of 97.3% (single explosion) and 98.8% (double explosions) over the unexploded settlements. The double explosion resulted in greater settlement than the single explosion condition; however, this difference increased with positioning depth, with a maximum difference of 79.9% at 40 cm depth, and decreased again at 50 cm depth. It can be seen that there is a critical depth of burial for settlement after explosion, which is 20 cm in this paper; the critical depth in the field is 4 m according to the similarity ratio. An empirical formula for the settlement of rockfill after the explosion has been proposed. The research results can provide technical support for relevant projects.