EVALUATION OF PRECONSOLIDATION PRESSURE EFFECT IN COMPACTED FILLS

Abstract

Low-lying areas and Marshy land are often required to be developed as sites for construction of residential buildings. To avoid flooding of the area and place foundations at an appropriate level, formation level of such sites is required to be raised through compacted fills Further, in situations where top soil is weak, it may be replaced by stronger compacted fill to improve bearing capacity and limit settlement of foundations fills may also be required to level undulating ground. Literature reports many cases where compacted fillc have formed an essential part of construction activity. In ancient time monument, building other construction activity had been made. This structure develop precosolidation pressure, this phenomenon have immense positive contribution as far as stability aspect is concerned. Literature, journal said that, this preconsolidation pressure reduces settlement, improve bearing capacity of soil and also have positive effect on stability. Therefore, researchers, designer adopt this phenomenon for construction activities. In general low lying areas, marshy land have low bearing capacity, so it is-until- or" for construction activities. Now, filling this area by land filling material layer by layer by compaction after that consolidation naturally develop precosolidation pressure in additive way and serve the basic purpose for construction. Increasing demand of electricity compel engineer to install thermal power plant and naturally it produce flyash and bottom ash as rejected material. It is but obvious that this material is major factor of concern. For environmentalist as well as authority for its i i i disposal. In metropolitan cities, natural material like soil, sand etc. is not easily available and in real sense flyash and bottom ash can be used as fills. So utilisation of this material as fills and low lying area and swampy land can be made fit for construction purpose. In nut-shell we can say that our major mission has been served. Literature indicate that flyash and bottom ash are produced in 80:20 proportion. For effective utilisation of these ashes, there is a need to establish the relative performance of fly ash, bottom ash and their combinations for structural fill applications. Sand is the other commonly used material as structural fill. It is a common practice in India that river sand available at a nearby location is used as fill material: The river sand, available in wet condition, is not amenable to high degree of compaction due to the bulking of sand grains. A detailed review of literature pertaining to the above aspects indicates that : (i) Suitability of coal ash has been established till now on the basis of index and engineering properties. Some applications of ash as structural fill have also been reported. However, knowledge base on relative performance of flyash, bottom ash and their combinations under load in various possible fill conditions, including submerged condition of fill of the above materials is lacking. (ii) Compacted ash bed are subjected to capillary stress due to contact moisture and preconslidation stress due to compaction process. These stress affect the compressibility of the fill material and reduce settlement.