BEHAVIOUR OF ECCENTRICALLY AND OBLIQUELY LOADED FOOTINGS ON REINFORCED FLY ASH

Abstract

The present investigation deals with the behaviour of eccentrically and obliquely loaded footings resting on reinforced fly ash. Shallow foundation is very common type of foundation provided for many structures. These foundations, in general, are subjected to eccentric-oblique loads. For proportioning of such foundations, ultimate bearing capacity, settlement and tilt are the main criteria. Coal based thermal power stations generates electricity on one hand which is essential for our development, on the other hand these power stations also produce massive quantities of coal ash mainly in form of fly ash which could pose serious environmental and other related problems. Disposal of fly ash is a major problem as the land is a scarce resource in our country. Utilization of fly ash solves two problems with one effort, elimination of a solid waste problem on one hand and provision of a much needed construction material on the other hand. Fly ash can be utilized in many areas like, embankments, building foundations etc. To construct the foundations on fly ash, it is necessary to study the behaviour of these foundations under eccentric-oblique loads. The objective of the dissertation is to study the behaviour of eccentrically and obliquely loaded footings on reinforced fly ash and to develop the non-dimensional charts to evaluate the bearing capacity, settlement and tilt of the footings. A 10 cm square footing is taken for the experiments and is tested on fly ash both in Optimum Moisture Content condition and Submerged conditions in case of unreinforced fly ash and reinforced fly ash. As the fly is a material of low bearing capacity it is necessary to reinforce it. Geogrid (Netlon CE-121) is used to reinforce the fly ash. The size of the reinforcement is kept as 2 times the size of the square footing. The geogrid is placed below the footing at 0.25 times the size of the footing. A specially designed loading device is used for the application of eccentric-oblique loads. The load on the footing is applied at the eccentricities of 0, 0.1, 0.2 and the inclination iii with vertical is kept as 0, 10°, 20°. The pressure-settlement and pressure-tilt curves for different load combinations are plotted and the ultimate bearing capacity, settlement and tilt are obtained both in case of unreinforced and reinforced fly ash. Further, from this data the non-dimensional charts are developed to evaluate the ultimate bearing capacity, settlement and ,tilt of footings. The ultimate bearing capacity values of the present study are compared with the corresponding values of the previous investigators.