Evaluation of load support capacity of remoulded fine and coarse textured soils as affected by wetting and drying cycles

Abstract

Soils of south of Iran used for sugarcane production are frequently exposed to wetting and drying cycles under flood irrigation. The effects of this process on estimation of the load support capacity (pre-compaction stress; σpc) of two soils using plate sinkage test (PST) and confined compression test (CCT) were studied. Large reconstructed specimens of topsoils were subjected to 5 wetting and drying cycles. The specimens, with/without wetting and drying cycles, were then compressed under two pre-loads (100 and 200 kPa) at two water contents (0.9 PL and 1.1 PL, where PL is plastic limit). The centre section of the preloaded soil specimens was firstly submitted to a 50 mm PST; then immediately one cylindrical sample was cored for CCT. The results indicated that for both soils, without wetting and drying cycles, σpc estimated from PST did not show any significant difference with the values of preload. This method can, therefore, be used to determine the load support capacity for tilled soils. However, wetting and drying cycles caused a significant over-estimation of σpc by PST. Thus, the concept of pre-compaction stress does not account for the effects of changes in soil structure due to wetting and drying.