Instrumentation and Monitoring of a Steel-Reinforced MSE Wall

Abstract

A two-span bridge, supported by steel H-piles and mechanically stabilized earth (MSE) bridge abutments, was constructed as part of a new interchange on I-65 in Whitestown, Indiana. The east and west MSE walls consist of precast concrete facing panels, ribbed steel strips, and coarse-grained backfill soil. A section near the middle of the east MSE wall was selected for instrumentation and performance monitoring. The instrumented wall section is 5.7 m tall and consists of four panels with seven levels of reinforcement. A variety of sensors, including earth pressure cells, strain gauges, inclinometers, and crackmeters were used to measure the magnitude and evolution of several quantities, such as the vertical stresses at the base of the leveling pad and within the backfill soil, the lateral earth pressure on the back of the wall facing, the tensile loads in the reinforcement, the lateral deflection of the wall facing, the contraction of the panel joints, and the settlement of the MSE wall foundation. The data was collected continuously, both during and after wall construction, using multiplexers and dataloggers powered by solar panels. The results indicate that the vertical stresses measured at the base of the leveling pad are greater than those measured along the base of the reinforced fill as well as those calculated based on the self-weight of the wall facing. The values of key parameters used in MSE wall design were determined from the instrumentation results and compared with those obtained using design methods available in the literature.