Undrained Shear Behaviour of Fly Ash-Geosynthetic System with Woven and Non-woven Geotextile

The use of geosynthetic reinforced soil structures in various geotechnical engineering applications is increased in recent times. Conventionally, free-draining materials such as coarse to medium sands are used as reinforced fill material. However, the availability of sands are decreasing rapidly, and that raised certain economical and environmental issues. Fly ash is a good alternative to the sand as reinforced fill material. It is a by-product generated due to coal combustion and contains silt-sized hollow spherical particles having very low specific gravity. In the current research, an attempt has been made to evaluate the shear behaviour of the fly ash-geosynthetic system under undrained triaxial conditions. A series of undrained triaxial compression tests were performed on 100�mm diameter and 200�mm height specimens of fly ash having zero to four layers of woven and non-woven geotextiles at 100, 200 and 300�kPa confining pressures. The peak deviatoric stress was enhanced with the insertion of geotextile layers due to an increase in effective confining pressure within the specimen, generated by the mobilisation of large tensile forces at fly ash-geotextile interfaces. The rise in shear strength was more prominent in the case of woven geotextile as compared to non-woven due to its high stiffness and high load carrying capacity. The post-peak softening response was reduced, and the hardening response was increased as the number of geotextile layers increased. The values of shear strength parameters (c and ?) had been increased from unreinforced to four layers of geotextile-fly ash system except for a single layer system. � 2021 Elsevier B.V., All rights reserved.