Swelling properties of clays, a major risk factor for the infrastructure projects

Abstract

Swelling and shrinking properties refers to significant positive or negative variations of volumes due to absorbtion or dessication of water in fine soils under natural or anthropic regime of moisture. These physical phenomena are worldwide spread and had important engineering consequences with associates cost of damages of several billion annually in all climate areas. In spite of the fact that these geotechnical properties are studied for more than eight decades, the particularities of these peculiar relations between water, mineral composition and geomechanical behavior are still unrevealed entirely. In Romania, swell/shrink soils are reported in all regions at different depths, but rarely related to geotechnical engineering accidents such as slope slides or road failures. This work presents some obvious relations between the hydrogeological structure, the presence of “large swell/shrink soils”, their mineralogical composition and geomechanical properties and the ubiquitous landslides on Peri Carpathians Hills. Large infrastructure projects offer the opportunities to put into evidence the swelling properties of Upper Pliocene-Lower Pleistocene deposits, which supports the Holocene alluvial deposits of Argeş River. Analyzed samples allow us to define some basic correlations between plasticity index, colloidal fraction, dry density, swelling pressures or free swelling and mineralogical composition.