COMBINED EFFECT OF EMBEDMENT DEPTH AND DIAMETER ON PULL OUT STRENGTH OF MODELED PILE

Abstract

Piles are used in civil construction work from the prehistoric times. They are used for supporting structures having large height, for example chimneys, transmission towers, high potential electrical poles and many more. All the above stated structures faces very high tensile uplift force and other forces which may cause extraction of the structure from the soil, hence pile or group of piles are designed to counter these force and to stabilize the structure, moreover pile/group of piles become indispensable support member when the soil is unstable and exceptionally large loads are involved. Resistance to high tensile uplift is given by the friction between the surrounding soil and the pile along with pile weight. Such piles (which counter uplift) are termed as uplift piles, anchor piles or tension piles, their computed uplift resistance is equivalent to that of friction piles. Uplift resistance is been developed by the uplift piles, from the skin friction generated along with the length of embedment. Uplift piles are driven in such a way that an inflated area is there at the base which expands to bulb like structure. Pile weight is included in this procedure of uplift capacity excluding the point bearing. In this study, theoretical as well as practical evaluation has been done in order to determine the pile’s ultimate uplift capacity when the same were embedded in sand. Different parameters were taken into consideration the soil properties and pile parameters like diameter, length, surface characteristics. In order to work out the uplifting capacity or pull out strength of piles embedded in sand, various charts has been generated. Description of analysis results of modeled pile laid into soil is presented in the study. In order to know the influence of various parameters like size of pile (diameter), embedment depth, comparison tests were done. Pile uplift capacity or pull out strength is not only the function of (depends on) denseness but

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it varies with method of laying of pile into the soil i.e. method of installation, depth up to which pile is embedded into the soil, material and size of pile, roughness etc. It is already known that uplift capacity/pull out strength of pile is only summation of frictional resistance and pile weight, on the other hand frictional resistance reaches a constant value after attaining critical depth.