Exhumed Geogrid-Reinforced Retaining Wall
Dov Leshchinsky1; Baris Imamoglu2; Christopher L. Meehan3
1Professor, University of Delaware, Dept. of Civil and Environmental Engineering, 301 DuPont Hall, Newark, DE 19716, U.S.A.
E-mail:
dov@udel.edu (corresponding author)
2Civil Associate, Michael Baker Jr., Inc., 300 American Metro Blvd.,
Hamilton, NJ 08619, U.S.A.
(Formerly, Graduate Student, University of Delaware, Dept. of Civil and Environmental
Engineering, 301 DuPont Hall, Newark,
DE 19716, U.S.A.)
E-mail:
baris@udel.edu
3Assistant Professor, University of Delaware, Dept. of Civil and Environmental Engineering, 301 DuPont Hall, Newark, DE 19716, U.S.A.
E-mail:
cmeehan@udel.edu
Journal of Geotechnical and Geoenvironmental Engineering, 2010, Volume 136, Number 10, pp. 1311-1323
Abstract
An instrumented geogrid-reinforced wall constructed on a highly compressible foundation was deconstructed 16 months after
its completion, providing a unique opportunity to exhume and examine the instrumented geogrids that were used to construct the wall. The
objectives of this post mortem study were: (1) to inspect the condition of the strain gauges that were attached to the geogrid layers before
construction and to verify the reliability of their output; (2) to develop a procedure in which the residual plastic strains along exhumed
geogrid panels could be determined; and (3) to assess the in situ strain and force distribution along geogrid panels based on the measured
residual strains from the exhumed geogrids. After exhumation, it was observed that many of the attached strain gauges failed due to full
or partial debonding from the geogrid, thus rendering outputs which potentially underestimated the actual strain. Combining aperture
measurements of virgin and exhumed geogrids, all from the same manufacturing lots, enabled the assessment of residual strains following
stress relaxation. Laboratory simulation of loading and unloading, including creep and relaxation, yielded a relationship between the
measured residual strains and the in situ strain and force distribution; i.e., the residual strain fingerprint provided insight into the behavior
of the geogrids within the wall prior to its deconstruction. The mobilized maximum tensile strains in the geogrid panels along the height
of the wall were roughly uniform, in the range 4 +/- 1%. These findings imply that if the same type of reinforcement had been used
throughout the height of the wall, the mobilized force along the height would have been relatively uniform. The back-calculated maximum
force in the geogrids indicated that the factor of safety on the long-term strengths of the geogrids ranged from about 1.4 on the
stronger/stiffer geogrid to about 1.8 on the weaker/softer geogrid.
Keywords
Creep; Geogrid; Reinforced wall; Strain gauge; Stress relaxation
Reference
Leshchinsky, D., Imamoglu, B., and Meehan, C. L. (2010). “Exhumed Geogrid-Reinforced Retaining Wall.” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 136(10), 1311-1323. (doi:10.1061/(ASCE)GT.1943-5606.0000354)
