Title: Performance of a Bridge Abutment on Mechanically Stabilized Backfill
Author(s): Nien-Yin Chang, Zeh Zon Lee, Hien M. Nghiem, Shing C. Wang, Yail J. Kim, and Aziz Khan
Publication: Symposium Paper
Appears on pages(s): 129-152
Keywords: bridge abutment, concrete abutment sill, field instrumentation, finite element analysis, geotextile reinforced soil (GRS), Integrated Bridge System (IBS), mechanically stabilized backfill (MSB), soil-structure interaction, earth pressure, settlement
Increasingly contemporary bridge abutments are supported on mechanically stabilized backfill (MSB) or geotextile reinforced soil (GRS) mass to enhance smooth ridership when vehicles transitioned from embankment to bridge deck with facing concrete blocks, rigid concrete panels or steel sheet piles to retain backfill. The bridge dead load and live load flow from bridge deck and girders to abutment sill, MSB (or GRS) mass, geo-textile, earth retaining structures and subgrade underlying MSB through interface interaction. Evaluation of the MSB abutment performance requires clear understanding of load transfer through interface interaction among neighboring materials. The replacement of the I-70 Twin Bridge in Aurora, Colorado made possible the implementation of a comprehensive instrumentation program to monitor the performance of abutment. Clean crushed rocks with minus
2-inch (50-mm) grain size, angular grains and less than 10% fines were used as backfill. Instrument monitor results
were used in the calibration of two selected computer codes. Finite element analysis results using both LS-DYNA and SSI2D were found to be in good agreement with the field instrument monitoring results. Earth pressures behind steel sheet pile façade, lateral deformation at top of sheet piles and geo-fabric tensile loads were found small at the time when this article was written; abutment settlements and lateral movement were less than one inch (25 mm).