Ground Improvement Reinforcement Mechanisms Determined for the Mw7.8 Muisne, Ecuador, Earthquake

摘要

The 2016 Muisne, Ecuador, earthquake caused widespread soil liquefaction and structural damage as affected sites were subject to peak ground accelerations of greater than 0.4 g. Liquefaction was observed in the silty sand foundation soils adjacent to the recently constructed Briceno Bridge embankment site as evidenced by sand boils and liquefaction ejecta. However, the nearly 1 km long Briceno embankment, whose foundation materials were reinforced by relatively widely spaced rammed aggregate pier ground improvement elements, exhibited only minor damage after shaking. Post-earthquake data indicated that the ground improvement works provided densification of the SM foundation soils. This densification was not sufficient, however, to fully explain the stability of the embankment, an achievement that necessitates the presence of other stabilization mechanisms. This paper is of particular significance because it presents proposed stabilization methods that reach beyond densification in difficult to densify soils such as silty sands and sandy silts.