Studies on Embankment Foundations with Soft Soil Reinforced with Prestressed Geosynthetic Encapsulated in Thin Layer of Granular Soil

Abstract

AbstractThis paper investigates the behavior of an embankment resting on soft clay reinforced with prestressed geogrid encapsulated in thin layer of granular soil. Over-excavation and replacement by geosynthetic reinforced granular soil is an effective technique to improve the load-settlement behavior of embankments resting on soft soil. The effectiveness of geosynthetic reinforcement embedded in clayey soil is very less due to poor interfacial strength and buildup of pore water pressure. But now the availability of granular soil is very less and it makes the reinforced soil technique uneconomical. It is also well established that geosynthetics demonstrate their beneficial effects only after considerable settlements. Thus, there is a need for a technique which will improve the bearing capacity without excessive settlement of reinforced granular soil. One technique yet to be comprehensively studied is prestressing the geosynthetic and encapsulating it in a thin layer of sand when used as reinforcement in clays. A series of finite element analyses are carried out using the FE software PLAXIS 2D to investigate the influence of prestressing the geogrid and encapsulating it in thin layer of sand on the load-settlement behavior of embankment foundations. The influence of prestress on the interaction between geogrid and granular soil is investigated by carrying out large-scale direct shear tests. It is observed that the load-settlement behavior and the interaction between geosynthetic and granular soil can be significantly improved by prestressing the geosynthetic reinforcement.KeywordsGeosyntheticsFinite element analysesEmbankmentPrestressBearing capacity