Surprising Soil Behaviour: Is It Really!!!

Abstract

Several instances of unexpected soil behavior, which either conventional or advanced forms of soil mechanics could not be explained are termed as ‘Surprising’. Several cases of unexpected behavior, more particularly heave in fine grained soils are due to contamination of foundation soil. An attempt is also made to understand and explain the mechanism of heave based on extensive laboratory and field studies on contamination of soils with strong acid and alkali solutions. Also the heave in lime stabilized soil in the presence of sulphate after long periods of interaction has been relooked with recent work. The mechanism and characteristics of occurrence of this type of heave in both swelling and non-swelling soils, which is different from conventional swell in expansive soil, is not understood. Conventional remedial approaches to control the heave would fail. Particular attention is paid to draw a special testing plan and analyzing the results from more fundamental principles. It was brought out that changes in the mineralogy of the soil which occur over geological ages (rock cycle) are triggered and occur in relatively shorter period due to interaction with strong acid or alkaline solutions. The associated changes in soil behaviour are explained based on mineralogical alterations, fabric and physic-chemical environment. Very often, more than formation of swelling minerals formed, the free energy released by mineral transformations controls the induced heave in soils. Some of these considerations are also important to overcome the problems in natural soils and initiate appropriate remedial measures.