للكاتب
By: Ahmed M. El-Tuhami
Civil Engineering Dept.,
Faculty of Engineering, Al-Azhar University
ABSTRACT:
The present study aims at examining the validity of reinforcing Rammed Aggregate
Piers RAP (which is a technique that has proved to be successful to strengthen soft soil)
with Geogrid shell. This technique depends on providing the soft soil layer with highly
compacted aggregate piers all over the foundation area. However there are different modes
of failure that are associated with this technique including shearing within the reinforced
layer and bulging of the pier. An experimental study has been carried out on a model pier
reinforcing a soft clay layer and statically loaded until failure for unshelled and Geogrid
shelled piers with different shelling lengths. Numerical analyses were conducted using
Plaxis Finite Element code (version 7.2) with Axisymetric modeling techniques. Test results
indicated that shelling of granular piers with Geogrid shell down to a depth of 5 times pier
diameter secures the pier against bulging failure as long as the Geogrid sheet is safe against
tension failure. Shelling of granular piers with a Geogrid shell significantly improves the
bearing capacity of granular piers, hence allowing this technique be used for soft clay
deposits stabilization.