Study of Load & Settlement Behaviour of Expansive Soil Reinforced with Granular Pile Using Natural Aggregates

Abstract

Expansive soil such as Black Cotton soil is problematic from geotechnical point of view as it is unstable volumetrically with the variation of seasonal moisture making it sensitive to deformation. Its strength decreases, compressibility increases on wetting, it possesses very small shear strength. There are several geotechnical improvement techniques available expansive soil strata, but the use of granular piles is becoming popular in India as it improves the strength parameters, such as increases load bearing capacity, reduces settlement, takes wide spread loads and improves the rate of consolidation. In this study, experimental investigations have been done to judge the load and settlement behaviour of Black Cotton soil when reinforced with geotextile encased granular pile by varying the percentage of natural aggregates, fly ash and lime at varying L/d (length & diameter) ratio of 1.5, 2, 2,5 3 and 3.5. The soil sample was prepared taking a mould of 150mm diameter, 175mm height and granular pile of diameter 50mm. The test results showed significant reduction in settlement on installation of geotextile encased granular pile when compared to untreated soil sample. The ultimate load increased & settlement reduced with increase in percentage of fly ash & lime with each increase of L/d ratio as well.