The objectives of the reported work were (a) to identify the failure surfaces developing in geosynthetically reinforced steep slopesand (b) to compare the observed critical results with those predicted by a limit equilibrium analysis. Failure surfaces were induced through all reinforcing strips (i.E., Internal failure) by the backfill self-weight in 60-, 75-, and 90-degree small-scale slopes. The backfill material consisted of an assembly of steel pins, which exhibited a constant internal angle of friction of 37.4 Degrees under stresses in the models. Its performance corresponded to plane strain conditions, and its uniform geometry enabled one to construct slopes repeatedly with ease and to nearly perfect specifications. The reinforcement material used was aluminum foil having a tensile modulus and elongation at failure that are typical of values specified for geosynthetics in design. All slip surfaces initiated at the lowest reinforcement layer and rapidly propagated upward. For 90-degree slopes, the slip surface appeared to be nearly planar, whereas for flatter slopes, it was curved. The test results were compared with predictions by a rigorous limit equilibrium analysis that uses a log spiral failure surface. The analysis indicates that this surface degenerates toa plane for 90-degree slopes. When the reinforcement's tensile force is assumed to be orthogonal to the radius vector defining it rather than to remain horizontal as installed, the predictions of the analysis correspond better to the test results in terms of both trace of slip surface and collapse height. Generally, it appears that the limit equilibrium analysis reasonably predicts the critical conditions for cohesionless slopes reinforced with extensible inclusions. This paper appears in transportation research record no. 1330, Behaviorof jointed rock masses and reinforced soil structures 1991
Abstract