Vertical and horizontal displacement of model piles in dry soil with horizontal excitation

Abstract

A series of laboratory tests was conducted to measure the vertical and horizontal displacement responses of pile foundations when subjected to dynamic loads. Eight tests were conducted on a single pile in dry soil at a relative density (RD) of 30% (loose) or 50% (medium); 66 tests on groups of piles with different spacings and patterns in dry soil at RD 30% and 50% were also performed. All the tests were carried out at operating frequencies of 0.5, 1 and 2 Hz under horizontal shaking and all considered one embedment ratio (L/d = 30). The tests were grouped in terms of the number of piles (two, three and four piles in row and line patterns) and three pile spacing ratios (s/d = 3, 4 and 5). The vibration box used in this work was able to simulate accurately earthquake motion induced on foundations and pile groups. An increase in shaking frequency led to a reduction in the oscillation of wave propagation values recorded due to densification of the soil during shaking. The pile spacing was found to be an important parameter that affects the time–frequency characteristics of displacement at the pile top. With an increasing in the pile spacing ratio s/d, the internal forces were slightly reduced.