In recent years, vibratory pile drivers have gained popularity with contractors due to the increased productivity that can be realized with their use. The driving time can be reduced by a factor of 10to 20 over that of an impact-driven pile. This gain in productivityis very attractive and profitable, but questions exist as to whether vibratory driving has an effect on a pile's axial capacity when compared with an impact-driven pile. This paper presents and discussesthe results of a study of three pile testing programs that make direct coparison between vibratory- and impact-driven piles. One of these testing programs has never before been reported in the literature. From the study of these testing programs, it was found that the vibratory-driven piles had a significant reduction in axial capacity when compared with the impact-driven piles. This reduction in capacity of the vibratory-driven piles was due to a lower tip resistance. This paper appears in transportation research record no. 1277, Modern geotechnical methods: instrumentation and vibratory hammers 1990.
Samenvatting