Experimental Study of the Effects of Installation of Sand Columns in Compressible Clay Using a Reduced Model

Abstract

The present study focuses on the investigation of the behaviour of a reduced model of a reinforced soil massif by a sand column tested in the laboratory. These tests involved the installation of sand columns in clay specimens (kaolin) by different methods. The specimens thus obtained are subjected to the same oedometric loading program. The first part of this work aims to study the effect of the intensity of the compaction stress of the sand columns on the surrounding soil and the effect on the behaviour of the soil-column massif. The sand columns were installed with the soil replacement method and with compacting of the columns (WR_WC). Three different compaction stresses were used to install the columns. In the second part, a sand column 20 mm in diameter was installed by two methods: one with replacement of the soil (WR) and without compaction and the other with displacement of the soil (WD). A comparison between the two methods has been established. By determining the equivalent characteristics for the soil-column massif, this study made it possible to characterize the effect of the installation method of the columns on the settlements, the void ratioe of kaolin, the equivalent void ratio eeq of the massif soil-column and on the compressibility parameters of the massif (equivalent compression index Cceq and swelling index Cseq), by comparing the results obtained with those of the unreinforced soils that constitute the reference case. The results obtained showed that the techniques used for the installation of columns have significant effects on the behaviour of reinforced massifs.