Coeficiente de reação vertical em estacas: efeito em blocos sobre três estacas alinhadas

Abstract

When there is a need to use a group of piles to support the loads in a foundation, several geometry options for the pile cap are available to the designer. For solutions with three piles, there are options of triangular blocks or aligned in a straight axis. In the latter case, one of the piles is centralized, demanding checks on the distribution of stresses, which depends on the relationship between the pile cap stiffness and the coefficient of subgrade reaction of the piles. This paper is a case study, which evaluates the influence of the vertical reaction coefficient of the piles in the load distribution of a pile cap with three piles in line. To do so, semi-empirical pile design methods were used to arrive at the allowable load values for four types of piles, in two diameters, applied in three boreholes of an SPT survey campaign performed in Toledo, in order to quantify their respective settlements. With the loads and settlements, the vertical reaction coefficients were calculated and compared to the fixed value recommended in the literature. It was verified that the fixed value proposed in the literature is conservative for piles with greater length and diameter, which results in a concentration of stresses in the central pile, but in small magnitude, without causing risks to the safety of the foundation.