Numerical analysis of a geo-tube subjected to seismic soil liquefaction

Geo-tubes are geosynthetic tubular containers, of various length and diameter, which are filled by pumping a fluid mixture of water and soil: the permeability of the geosynthetic allows water to drain rapidly so that at the end of the installation a solid nucleus is obtained. Considering that geo-tubes have been widely used as submerged elements, for example for shoreline protection, and that the filling material is a low density loose soil, hydraulically deposited, they may be subjected to liquefaction during seismic events. In order to investigate the behavior of a single submerged geo-tube when subjected to soil liquefaction, a numerical analysis is presented. The El Centro earthquake was considered and, under this solicitation, a rapid buildup of the pore pressure in the filling soil was observed. Consequently, since the first seconds of the seismic event, a decrease of the effective vertical stress took place up to values close to zero, showing the capability of the model to replicate a condition of soil liquefaction. At this stage, a general increase of the tensile force in the geosynthetic was noted, up to values that are significantly higher than those experienced in the static phase.