Geotechnical investigations into the characteristics of cracking and damage analysis of low rise buildings due to shrink-swell potential of Expansive soils

Abstract

Expansive soils which occur in arid and semi-arid climate regions of the world cause serious problems on Civil Engineering lightly loaded structures. In recent years, the focus of research lies in understanding the influence of Geotechnical characteristics of such problematic soils. Expansive soils cause damage to houses, other buildings, roads, pipelines, and other structures which is more than twice the damage from floods, hurricanes and earthquakes. Only a few studies have been described in the Indian context. Ten low rise buildings from different locations 1 to 10 are selected for Geotechnical investigations and analysis at Pondicherry region of East coast India. Three soil samples from each location under different ground conditions are collected and tested The characteristics studied are initial moisture Content, Dry Density, Liquid Limit and plasticity Index, shrinkage limit, free swell index, natural moisture content, compression index, liquidity index (LI), consistency index (Ic) activity, specific gravity, and cation exchange capacity. The ratio of Plastic Limit to Liquid Limit of the soil varied from 0.49 to 0.71indicating the characteristic of high plastic clay at depth varying from 1m to 3 m. The author attempts to describe criticality of physical defects in the building system using multi criteria decision analysis approach considering two case studies. The cracks are analysed with respect to crack width, crack orientation, and crack intensity into a relative physical condition with the building systems as alternatives. This technique could be used in monitoring the progression of cracks in the building elements. Preliminary investigation includes visual inspection of cracks, structural damages followed by a detailed assessment of damages along with Non-Destructive Test (NDT). Visual inspection and non-destructive tests indicate the distress found in the case studies can be categorized as partial and complete impairment due to soil behaviour and poor construction materials used in the buildings.