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PREDICTION OF THE PERFORMANCE OF A GEOGRID-REINFORCED
SLOPE FOUNDED ON SOLID WASTE
JORGE G. ZORNBERG and EDWARD KAVAZANJIAN JR.
ABSTRACT :
An investigation was undertaken to evaluate the integrity of a geogrid-reinforced
steep slope subjected to significant differential settlements and
seismic loading. The reinforced soil structure under investigation was
constructed in 1987 in order to enhance the stability of steep landfill
slopes at the Operating Industries, Inc. (OII) Superfund site, a
hazardous waste site in southern California. The site is in an area of
high seismicity. The 4.60 m high, 460 m long geogrid-reinforced
structure was founded, along most of its length, on concrete piers
located towards the front of the structure. However, as the back of the
reinforced slope was founded on waste, the structure experienced more
than 600 mm of differential settlements ten years after its
construction. A geogrid experimental testing program was implemented to
evaluate the performance of the reinforcements when loaded rapidly after
a period of constant load. A finite element numerical simulation was
performed to assess the integrity of the geogrid reinforcements when
subjected to 30 years of additional differential settlements followed by
the design earthquake. The maximum geogrid strains predicted for a
sequence of expected static and extreme seismic loadings were found to
be well below the geogrid allowable strain values, indicating that the
integrity of the structure should be maintained even when subjected to
large differential settlements and severe earthquake loads. The
numerical results show that the critical reinforced zone (i.e., the
reinforcement layers that are strained the most) that corresponds to
different loading mechanisms (construction, differential settlement,
seismic loading) occurs at different elevations within the reinforced
soil structure.
Key words: soil reinforcement, landfills, geosynthetics, geogrids,
case histories, differential settlements, finite element analysis,
seismic design, steep slope (IGC: B3, E6, H2).
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