| Abstract: | In this research program, a new constitutive model which combines the Drucker-Prager model and Duncan's model was developed and used in a finite element analysis to model load tests on spread footings on sand. Strain distribution under the footing was analyzed and a method, based on the concept of the strain influence factor, was developed to predict the load settlement curves. Unfortunately this method requires parameters that cannot be measured reliably in situ and is, therefore, of limited interest. To make up for this deficiency, pressuremeter tests were then studied with the same constitutive model. The analogy between the load settlement curves and the pressuremeter curves was used to develop a method of prediction based entirely on pressuremeter results. The method consists of running several pressuremeter tests at different depths. These pressuremeter curves are then normalized and averaged by special procedures to obtained a single averaged pressuremeter curve. This single curve is then multiplied by a correction factor Γ to generate a normalized load settlement curve which is then easily transformed into the actual load settlement curve. This new method is so far restricted to the case of a vertical centered load acting on a square spread footing resting on flat ground. In addition, by using the results of a creep test included in the pressuremeter curve, not only can the initial load settlement curve be predicted, but also the load settlement curve at any time after application of a given load. Very little experimental data exists in the literature to compare with the proposed method. The geometry and the embedment of the experimental footings described in the technical literature are not similar to those modeled in this work. However, a comparison of the theoretical results with the experimental results is satisfactory and validates the proposed method. Recommendations for further work are included. |
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