Mechanically Stabilized Earth Walls with Intersecting Horizontal Obstruction

Abstract

This study is a numerical exploration of the performance of mechanically stabilized earth (MSE) walls with intersecting horizontal obstructions. Utility pipes may intersect the MSE wall at different depths, within the reinforced soil, or under the wall’s foundation. The interaction between utility pipes and MSE walls is investigated, particularly focusing on the effect on wall stability and reinforcement. The finite-element analysis software Plaxis 2D is used to simulate an actual MSE wall from the Indiana Department of Transportation (INDOT); a circular pipe runs parallel to the wall. Cases considered include the MSE wall and pipes running parallel, perpendicular, and at an angle to the wall. The influence of pipe location on the factor of safety, axial force, and reinforcement displacement is examined, as well as slip and soil yielding around the pipe. The results show that pipes significantly affect the axial force and displacement of nearby reinforcements, with pipes running parallel to a wall increasing the axial force by up to 50% compared with a wall without obstructions. However, the pipe does not affect the internal stability of the wall (if each reinforcement has an adequate factor of safety). Furthermore, pipes alter the stress distribution within the reinforced soil. Interestingly, pipes positioned perpendicular or skewed to the wall may reduce reinforcement demand by acting as large frictional surfaces. The influence of the pipe on reinforcement demand extends to about 2–2.5× the pipe diameter. These findings highlight the necessity for consistent guidelines on utility pipe placement inside MSE walls.