Narrow Shored Reinforced Earth Wall with Friction-Based Reinforcing Strip Connection As an Innovative Solution to Expand Urban Highways

The increasing trend of widening urban highways in the U.S. has created the need for a hybrid type of retaining wall which allows new narrow MSE-type walls to be constructed in front of existing MSE structures or other types of retaining walls. The width of such narrow reinforcement zones are typically less than 70% of the wall height, as is typically required for conventional MSE retaining walls. The paper discusses a project where an innovative, flexible and friction-based connection, referred to as a "Sandwich Connection", was utilized to achieve the required internal and external stability of the combined wall system. The project required a new wall to be constructed in front of an existing MSE wall with aspect ratio significantly less than the typical 0.7H. The selected connection system was first modeled using numerical analyses developed with input from field cases in South Africa. Findings from the modeling and field studies showed that the introduction of overlapping reinforcements substantially reduces the horizontal stresses within the MSE volume, which lower the tensile forces within the reinforcing strip elements.