Centrifuge model studies on anchored geosynthetic slopes for coastal shore protection

This paper evaluates performance of anchored geosynthetic systems (AGS) on stability of slopes under seepage condition using a centrifuge modeling technique. A series of centrifuge tests were carried out at 50 g on unreinforced and AGS slope models, using a centrifuge container equipped with seepage flow simulator. AGS slope models were tested by varying slope inclination, number of anchors and keeping inclination of anchors as constant. The water was allowed to seep through the model slopes during flight at 50 g. Ground anchors were modeled as drilled pre-tensioned anchors using sand epoxy mixture, polyester strand and a plastic tube. An anchor inclination of 15° with the horizontal was adopted for AGS slopes. A layer of geocomposite was used for modeling geosynthetic component of anchored geosynthetic systems. All models were instrumented to measure surface settlements and pore water pressure within the slope at onset of seepage during centrifuge test. A digital image analysis technique was adopted to trace displacement vectors of plastic markers embedded toward the front elevation of the model and plastic markers glued to facing during model construction. Analysis and interpretation of centrifuge model test results indicate that the stability and deformation behavior of slopes, under seepage conditions, can be substantially improved using anchored geosynthetic systems. With an increase in slope inclination and reduction in number of anchors, surface settlements and face movements were observed to increase substantially. Further, stability analysis results on the unreinforced and AGS slope models were found to be in good agreement with those of physically observed centrifuge test results.