Many static methods and dynamic formulae are available in the published literature, for predicting the pile capacities. So also, the procedures for evaluating the ultimate capacities based on the load test data. All these methods and procedures, instead of providing unique answer, give different load values. Thus placing the designer in a dilemma with respect to the method that is to be adopted.Most of experimental suggestions are based on the results of small size piles driven in sandy deposits. But none of these suggestions try to dwell upon their limitations.In the present study an attempt has been made to analyse the behaviour of isolated piles, based on series of field tests, conducted on bored piles with enlarged base in a uniform deposit of silty sand.The performance mechanism of isolated piles have been studied. Also suggestions for estimating their capacities based on load tests and static methods have been provided. The predicted load-settlement behaviour by the elastic theory approach does not agree with the observed one.

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Model test results for determination of uplift capacity of square and rectangular foundations in clay have been presented. The model foundations were made out of 3.18 mm thick aluminum plates. The length-to-width ratio of the plates used in the tests varied from one to five. The experimentally determined net uplifting loads have been presented in terms of breakout factors (Vesic, 1971). The variation of the critical embedment ratio and breakout factors for shallow and deep foundation conditions have been analyzed. The uplift capacity of the square plates obtained from the present test program have been compared with the model test results of other investigators conducted on circular plates.

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Comprehensive tests were performed to obtain hysteretic dampings of normally consolidated reconstituted sands with use of a resonant-column apparatus and a static torsional shear device. It is shown that there is a simple relationship between the ratio of shear modulus to the shear modulus at very small strain level and damping ratio for sands tested. This relationship is not affected considerably by void ratio and confining pressure for shear strain amplitude from 10^-6 to 10^-2. For a given value of G/{G}_γ=10^-6; the ratio of shear modulus to that at γ=10^-6, the values of damping ratio of clean sands tested are slightly larger than those of other reconstituted natural sands. For these two kinds of sand, average curves representing the relationship between damping ratio and G/{G}_γ=10^-6 are shown.These curves can be used for design purposes to evaluate damping ratio of sands from the value of G/{G}_r=10^-6.

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