BEHAVIOUR OF REINFORCED BLACK COTTON SOIL

Abstract

Well-built and maintained highways/railway tracks play major role in the development of any nation. The subgrade soil is an integral part of these structures as it provides the support to the pavement. The subgrade soil and its properties are important in the design of pavement structure. Most state highways in central part of India (e.g. Maharashtra, M.P) have problems of foundation due to the presence of highly compressive clayey soil (mostly black cotton soil). In present study, an attempt has been made to investigate the settlement and shear strength behaviour of black cotton soil procured from Navibag, Bhopal, (M.P), reinforced with layers of Woven /Non-woven jute geotextile (JGT), Non-woven geotextile and coarse sand drain placed at centre in horizontal layer and in fonn of vertical drain. Results show that compression index values decrease by about 8 %, 16.5% and 25% with Non-woven JOT, Woven JGTand Non-woven geotextile respectively when compared with virgin black cotton soil. Further it is seen that by addition of 10 mm vertical coarse sand drain in the centre, compression index values decrease by about 35.6 %, 36.5% and 37.65 % with Nonwoven JGT, woven JGT and Non-woven geotextile respectively in comparison with virgin black cotton soil. When compression index is compared with only 10mm vertical coarse sand drain and 4 mm horizontal coarse sand drain, it is seen that it decreases by about 36.76 % and 20 % respectively as compared to virgin soil. It is observed that shear strength increases by about 13 %, 9%, 1.5 % and less than 1% with Non-woven geotextile, woven JGT, vertical coarse sand and horizontal coarse sand drain respectively when compared with virgin black cotton soil.