Behavior of Laterally Loaded Step Tapered • Bored Piles in Calcareous Cemented Sand

Abstract

The behavior of laterally loaded step tapered bored piles in calcareous cemented sand is studied. Effect of enlarged length on ultimate lateral capacity and deflection at pile head is investigated. Ten lateral load tests on straight and step tapered bored piles were carried out at a site in Kuwait. The straight piles were 0.2 m and 0.3 m in diameter. The step tapered piles are 0.3 m in diameter along the upper 10%, 20%, and 40% segment changing to 0.2 m for the lower section. The test results are compared with analytical predictions via linear and nonlinear approaches. This study shows that use of step tapered piles is highly efficient in design against lateral loads. Enlarging the upper pile section beyond a length of about 7 times the larger diameter (40% of its length) has little effect on increasing the ultimate lateral capacity. Pile head defection decreases substantially" as the pile is strengthened over the upper length of 3 times or more the larger diameter. Linear subgrade reaction theory gives predications which are not in agreement with the nonlinear pile response, whereas nonlinear analysis based on p-y curves employing the measured soil strength parameters yields load-defection response close to measurements. A significant zone of bending moments is evident in the upper segment of ten times the larger diameter.