Seismic response of basal geogrid reinforced embankments supported over floating and end bearing piles

Abstract

Embankments, roads and bridges are very important components of infrastructure. It is equally important that these structures are also able to resist earthquake forces and be functional at all times. Since the bridge rests on rigid deep foundations and the approaching embankments to the bridge on both sides could be resting on weak and compressible soil, the bridge and embankment junction always experiences differential settlement problems. To overcome these settlements, construction of approach embankments supported by pile foundations with basal geogrid reinforcement is a viable solution. Lot of studies are available in literature on the analysis of these geogrid reinforced pile supported embankments subjected to static loading conditions. Very few studies are available on geogrid reinforced pile supported embankments (GRPE’s) subjected to seismic excitations. Hence in the present study, 3-dimensional finite element analysis of 3 m high embankment made of pulverized fuel ash having crest width of 20 m and side slope of 1V:1.5H resting on 28 m thick soft marine clay subjected to seismic loading is considered. The soft marine clay is provided with 300 mm diameter RC piles having 22 m, 24 m, 26 m(Floating piles) and 28 m (End bearing piles) lengths arranged in a square grid pattern with centre to centre spacing of three times the diameter of the pile. Geogrid with tensile modulus of 2500 kN/m is considered as basal reinforcement. Maximum vertical and horizontal displacements along the embankment, settlement reduction ratio, differential settlements at crest, vertical and horizontal displacements at toe are evaluated. The embankment resting over end bearing pile stabilized soft marine clay experiences less settlements, less toe horizontal displacements, less differential settlements, larger settlement reduction ratio than the embankment resting over floating pile stabilized soft marine clay. © 2019 Associazione Geotecnica Italiana, Rome, Italy.