Abstract:
Collapsible soils are the most widely distributed and costly of geologic hazards. These soils are subjected to change in volume and settlement in response to wetting and drying, often resulted in severe damage to structures. Collapsing soils are generally characterized by sudden and large volume decrease at constant stress when inundated with water. These are very sensitive to changes its porosity and water content. Suffusion i.e. grain movement in a ground layer from one horizon to another during wetting up is one of the main causes of collapse. Man- made fills, which were compacted at the optimum water content, may also develop a collapsible or metastable-structure at low density. A sound understanding of the mechanical behaviour of this type of material is thus required so that the engineer can devise safe and cost-effective solutions to these problems. A geotechnical engineer needs to be able to identify readily the soils that could collapse and to determine the amount of collapse that may occur. Most compacted soils have collapsible soil behaviours when, subjected to wetting or loading. Collapse potential increases with decrease in compaction water content, high void ratio and low dry density. The main theme of this study is to know the influence of variations in compaction dry density, initial water content, inundation stress, and void ratio on the collapse behaviour of the soil. Also, to determine the collapse behaviour of soils under wetting conditions by using oedometer test and control of collapse behaviour of soil.
Keywords: Collapsible soils, Water content, dry density, Oedometer test, Metastable structure.