31-01-2012, 12:26 PM
Seismic Stability of Soil Nail Walls
Seismic Stability of Soil Nail Walls.pdf (Size: 843.53 KB / Downloads: 55)
E-1-Background
Vucetic et al (1997) analyzed the stability of soil nail excavation that were shaken by the
1989 Loma Prieta Earthquake. In brief, the performance of nine different grouted soilnailed
excavations in the San Francisco Bay area during the October 17, 1989 Loma
Prieta earthquake was analyzed on the basis of post-earthquake visual inspections,
subsequent stability analyses and dynamic centrifuge model tests. None of the
excavation showed any signs of movements or significant distress, even though one of
them was located in the vicinity of the earthquake epicenter which experienced strong
shaking and important seismic-related damage to other structures.
E-2-Seismic Soil Nail Stability Evaluation
As implied by the foregoing discussion, a rational procedure to evaluate seismic response
of permanent soil nail walls is by the evaluation of seismic induced deformations just as
is the case for slope stability. The minimum acceptable deformation is judged to be 0.5
percent of the height of the wall or 0.5 inch whichever is larger unless the physical
constraints of the project dictate smaller deformations.
E-3 Discussion
The nine wall configurations as reported by Vucetic et al are summarized on Figure E-4.
The analysis results tabulated in Table 1 for eight of walls shown on Figure E-4 were
plotted and interpolated and extrapolated to compute yield acceleration as a function of
initial computed factor of safety. The results are plotted on Figure E-5. As shown on
Figure E-5, Ky increase with increasing initial static factor of safety in a relatively narrow
range for 7 of the 8 walls.