Determinação da capacidade de carga de estacas raiz a partir de parâmetros de campo

Abstract

In the stage of execution of the foundations of buildings, it is usually carried out the process of evaluation of performance of the foundation, which consists in the application of specific methods to evaluate the load capacity of the foundation element. For root piles, the control is generally performed on the basis of performing static load tests. The main objective of this work is to propose an empirical model for predicting the load capacity of root piles. This model is based on an executive monitoring process in which some variables related to the execution of the piles are monitored during the excavation and later used for the calibration and validation of the empirical formulation. For this, seven piles were analyzed in four distinct building sites in the city of Fortaleza. Static load tests were performed on all seven piles monitored. The sites were previously selected and have subsoils with a variable geotechnical profile. Each pile was monitored during its execution and variables such as speed of excavation and rotation of the rotator were collected, which later were related to the lateral and tip load capacity of the piles. The reference value for the load capacity was obtained from the results of the load tests using the Van der Veen (1953) method. Then, the multiple linear regression technique was used to obtain a relation between the load capacity and the independent variables that were monitored during execution. Two kinds of models were created: a linear model and a power model. The obtained expression presented good results in the steps of calibration and validation, generating values concordant with the reference values of the load capacity of the piles. The power model was more adequate, since the equation obtained presented correct physical sense between the variables. For comparison purposes, the main semi-empirical methods of the literature were also applied in predicting the load carrying capacity of the cuttings. Among those, the method of Lizzi (1982) was the one that presented more consistent estimates with the reference values. With the accomplishment of this work it was possible to show that the proposed methodology can be an alternative for the executive control of root piles.