Ozgur L. Ertugrul

Reduction of Lateral Earth Forces Acting on Rigid Nonyielding Retaining Walls by EPS Geofoam Inclusions

Expanded polystyrene (EPS) geofoam panels of low stiffness installed vertically against the rigid nonyielding retaining structure provide additional deformations in the backfill. This behavior will lead to the mobilization of a greater portion of the soil strength, thus decreasing the lateral earth thrust acting on the rigid retaining wall. This study addresses the effect of geofoam compressible inclusion on lateral earth thrust acting on a rigid nonyielding retaining wall by small-scale model tests and numerical analyses. The finite-element code used in the numerical modeling is validated against the stress measurements on a 0.7-m-high wall model. Significant reduction is observed in the lateral earth pressures attributable to deformations concentrated at the lower half of retained soil mass. The effects of compressible inclusion thickness, relative stiffness of the EPS geofoam, and strength parameters of the backfill on lateral earth thrust acting on rigid nonyielding walls are investigated by a series ...

Geomechanics of a snowmelt-induced slope failure in glacial till

An integrated approach involving field, laboratory and numerical investigations was undertaken to study the progressive deformation mechanism of a slope in glacial till above the Town of Alta, Utah that experienced catastrophic failure due to rapid snowmelt in June 2010. Detailed geometry of the slope surface and of the exposed sliding surface obtained from global positioning system surveying together with strength and stress–strain parameters derived from laboratory triaxial tests on undisturbed samples of glacial till collected from the landslide site were employed with finite-element modeling to examine the effects of an increase in snowmelt-induced perched water table on the yielding behavior of the slope prior to catastrophic failure. The numerical results indicate gradual development of a plastic yield zone along the sliding surface with progressive rise in the perched water table above the toe of the slide mass, which was spreading out throughout the slide mass at the stage corresponding to the onset of catastrophic slope failure. The evolution of the slope safety factor obtained from limit-equilibrium stability analyses in relation to the development of the finite-element computed yield zone along the sliding surface is also discussed.

Reduction of Lateral Earth Forces on Yielding Flexible Retaining Walls by EPS Geofoam Inclusions

In the light of recent research showing that expanded polystyrene (EPS) geofoam inclusions possess the ability to reduce lateral earth forces on rigid nonyielding retaining walls, this study investigates the potential application of geofoam as a compressible inclusion behind yielding flexible retaining walls. In this context, results of static physical tests on a 0.7m high cantilever retaining wall with dry cohesionless backfill were addressed. In the physical modeling study, wall deflections and lateral earth pressures were monitored to investigate the effect of EPS geofoam inclusion on the behavior of cantilever wall models. It was found that an increase in wall flexibility resulted in a decrease in the load reduction efficiency of the geofoam inclusion since the active stress conditions may already be achieved in the retained soil mass due to lateral wall deflections. However, the geofoam inclusion still provides an additional reduction of lateral force and flexural deflections of the cantilevered flexible walls due to the arching effect induced in the retained soil mass by the lateral compression of the geofoam panel occurring predominately in the lower mid-height of the wall stem.