Full-scale field studies of the dynamic response of piles embedded in partially frozen soils

Abstract

The influence of a frozen soil layer on the dynamic response of full-scale concrete piles subjected to strong horizontal excitation was studied. The study undertaken compares the field observations against the theoretical predictions and provides an insight into the role of the yielded zone (boundary zone) in theoretically matching the field observations. The field measurements are used to postulate empirical relationships that can be used under practical conditions to estimate the magnitude of soil separation around piles embedded in cohesive soils as a function of the maximum vibration amplitude. The tests performed indicate that the presence of a frozen soil layer, even at a modest thickness of less than 0.5 m, can significantly influence the dynamic response of piles; the horizontal stiffness of the pile was increased by one order of magnitude, and its resonant frequency was increased by a factor of four compared to the situation with no frozen soil layer. The qualitative and quantitative findings from this study are considered to have practical applications in the design of piles under similar conditions as well as in providing a field validation of the theoretical solutions that have been developed for analyzing the dynamic response of piles. Key words: dynamics, vibration, piles, full-scale tests, frozen soil, modelling, resonance, soil separation, soil yielding.