Mechanically Stabilized Earth Pressures against Unyielding Surfaces Using Inextensible Reinforcement

This article presents experimental data on the earth pressures that develop between mechanically stabilized earth (MSE) wall panels that are tied together in an unyielding condition. Prior to design and construction, an extensive literature review was conducted to ensure the MSE wall adhered to the local standard specifications for road and bridge construction, current design codes, and the construction sequencing specified by the wall panel manufacturer. The Strong Wall at the University of Florida’s Structures and Materials Laboratory was utilized to construct a model full-scale MSE wall using inextensible reinforcement, with 140 locations continuously monitored. The MSE wall was divided into two different relative compaction zones, 95% and 103% of the reinforced soil’s optimum dry density, to investigate a range of friction angles that can develop during conventional construction. To achieve the necessary aspect ratio of 0.3 specified by practitioners for use in real-world applications, a reaction frame was incrementally loaded on top of the reinforced backfill to simulate additional wall height and overburden stress. Earth pressure coefficients were found for each compacted soil lift and incremental load from the reaction frame for both states of soil density. A force equilibrium analysis was conducted to ensure all forces within the experimental setup were accounted for to validate the results. From the derived earth pressure coefficients, it was observed that earth pressures moved from a passive condition to an active or at-rest condition as the soil-height increased above each reinforcement level. It was concluded that increased lateral stress develops from the compaction effort in an unyielding condition, which is not accounted for using conventional MSE design methods. Consequently, an equation was developed that incorporates a variable friction angle ($\phi$) based on the compaction effort for an unyielding condition that closely followed the trends of the measured results.