Laboratory Investigation of Earth Walls Simultaneously Reinforced by Strips and Random Reinforcement

The performance of reinforced earth structures depends, among other factors, on the shear strength of the backfill material used in construction. The shear strength can be enhanced by the use of random reinforcement. This paper presents the result of laboratory investigations concerning the effects of several types of random reinforcement on soil strength and, in particular, on the performance of reinforced earth model walls. Six series of experiments were conducted, in which a medium sand randomly reinforced by various metal particles was used as a backfill material for construction of 32 model walls. In construction of the walls standard reinforcement (horizontal metal strips attached to facing units) was used as well. The results obtained from shear box tests and from observation of model wall failures indicate that the presence of random reinforcement could lead to a significant increase in the critical height of model walls. An increase of up to 13% was observed as a result of adding only 0.5% of random reinforcement to the sand used for the construction of model walls. It was also found that fiber-like shapes of random reinforcement particles give a more significant increase in the soil strength and critical height of walls than other shapes tested. It might be reasonably expected that a small quantity of similar random reinforcement used in full-scale constructions could lead to a significant increase of their design height or, alternatively, to a decrease in volume of standard reinforcement needed.