Effects of installation method on sand compaction piles in clay in the centrifuge

The effects of the method of installation of centrifuge model sand compacti on piles (SCPs) in soft clay are studied. The comparative study involves th e frozen pile method, a 1-g displacement method, and a high-g displacement method. The results show that, although all the SCP-improved models exhibit higher strength compared to the unimproved models, both displacement metho ds confer additional enhancement in strength to ground improvement, which w as not present in the frozen pile models. In addition, wavy settlement patt erns were also observed in the frozen pile models, but not in the displacem ent models. The observed differences were explained by the postulated diffe rences in stress states of the improved models. For the frozen pile models, thawing during reconsolidation was postulated to lead to a reduction in ef fective lateral stress, resulting in further softening of the clay. On the other hand, the cavity expansion effect caused by the displacement methods was postulated to lead to a set-up in the strength of the clay, thereby res ulting in better integrity in the response of the improved ground to loadin g.