4 slope Stabilization With EPS Geofoam

4.6         Summary

·         The factor of safety of slopes can be increased using geofoam stabilization for both static and dynamic conditions.

·         A number of parameters including the amount and the distribution of foam blocks, soil characteristics, geometry of slope affect the factor of safety of a geofoam stabilized slope.

·         The effect of amount and distribution of foam on the factor of safety are controlled by the type of soil.

·         Using geofoam blocks in cohesionless soil slopes, where shallow failure surface occurs, will not affect the factor of safety at all.

·         Modeling geofoam blocks as cohesive soil with a very high cohesion value using the limiting equilibrium analysis is same as modeling geofoam blocks as elastic material using finite difference analysis.

·         For cohesive soil, the failure surface of geofoam-stabilized slopes is deep, either surrounding the whole amount of foam or forming on the slope side of the foam.

·         For geofoam stabilized cohesive soil where failure surface tends to develop only on one side of the foam, increasing the amount and the distribution of foam will increase the factor of safety of the slope until the slip surface occurs. Any further amount of foam will not increase the factor of safety of the slope.

·         For geofoam stabilized cohesive soil slopes in which the failure surface develops on one side of the foam and ends on the other side of the foam, increasing the amount of foam increases the factor of safety up to a certain amount. Beyond this point, the slip surface starts to form only on one side of the slope. Any further amount of foam will not increase the factor of safety of the slope.

·         For cohesive soil with an amount of friction particles, the failure surface of geofoam-stabilized slopes is shallow and develops on the slope side of the foam. Any increase in the amount of the foam in this case does not affect the factor of safety.

·         In general, the more the amount of foam, the more the factor of safety as long as the slip surface does not develop on the slope side of the foam.

·         For the same amount of foam, the closer is the foam to the slope side the higher is the factor of safety, as long as the failure surface does not develop on the foam slope side.

·         For the same amount of foam, the closer is the distribution of the foam to the circular shape (i.e. with two inclined edges) the higher is the factor of safety, so long as the failure surface does not develop on the slope side of the foam.

·         Parameters affecting the factor of safety of geofoam-stabilized slopes under static loading will affect the factor of safety under dynamic loading.

·         Geofoam stabilization leads to a steeper slope whose factor of safety is higher. A steep slope also increases the usable space.