Monitoring the Performance of a Steel-Reinforced Mixed MSE Abutment Wall during and after Construction

This paper presents a case study of the performance of a pile-supported, mechanically stabilized earth (MSE) bridge abutment in Whitestown, Indiana, both during construction and while in service. A zone near the middle of the east MSE abutment wall (Bent 3) was instrumented with earth pressure cells, strain gauges, inclinometers, and crackmeters to investigate the transfer of dead and live loads from the bridge to the foundation elements (pile cap and piles), and to assess the performance of the MSE abutment wall under these loading conditions. The results indicate that the vertical stress measured at the base of the leveling pad was greater than that calculated based on the self-weight of the wall facing by a factor of 2–3 during bridge construction. The measured dead loads carried by the instrumented piles were compared with the estimated dead loads used in the design of the MSE abutment. No significant changes were observed in the response of the MSE abutment wall after the bridge was constructed and opened to traffic. A live load test was performed by parking 12 triaxle trucks at different locations along the approach to the instrumented MSE abutment and on the bridge deck near the abutment. Most (≈91%) of the live load in the instrumented zone of the pile cap was carried by the piles, and the remaining 9% of the live load was carried by the fill material in contact with the pile cap.