2611
Technical Committee 211 /
Comité technique 211
Figure 3.slopes12-meter, reinforced with sandwich technique
5 HOW TO MODEL
First defining the model geometry and thenrequired parameters
are considered for different scenarios of various materials.
Given the importance of the boundary conditions on the both
sidesthe slope is anchored inthe horizontal direction (x) and in
downwardslope horizontal and vertical directions (x, y) are
anchored. Then geotextiles with distances equal to 1.5 m with
the same length have been modeled. And following given the
characteristics of the geotextiles, the suitable interaction
parameters are involved between soil and geotextile. Then thin
layers of sand with equal 30 cm thickness are considered to
simulate the effect of sandwich technique inreinforcement
process on the border between the reinforcement element and
the clay soil (geotextile),given the different distances between
the layers.
6 THE RESULTS OF NUMERICAL MODELING
After modeling and static analysis using software it evaluates
and compares the factor of stability safety in slopes for different
heights and different modes of reinforcement as follows.
6.1
Results of static analysis on slopes with different heights
According to the analysis results, finite differences of
reinforced clay slopes are shown as 6, 9, 12, 15 m, factors of
safety in different states of reinforcement as computed (figures
4 and 5) and includes three modes 1- clay Model (C), 2 - clay
with geotextile (CG), 3 - Sandwich Technique (CGS)
According to the output of numerical modeling analysis and
the results shown in the above graphs, adding layers of sand on
both sides of geotextiles(sandwich technique) increases
significantly factors of safety at different height (6,9,12,15 m).
In Figure 6 this technique has a greater impact on stability of
clay slopes in above heights and further increases the factor of
stability safety.
Figure 4. Comparison of factors of safety in 9 m slope
Figure 5. Comparison of factors of safety in 12m slope for
geotextiledistances intervals in both 1 and 1.5 meter
stability safety.
Figure 6. Comparison factors of safety of slop different heights in
various states of reinforcement
7 CONCLUSION
- Analyses showed that the sandwich technique is an effective
method of stabilizing clay slopes for engineers and results of the
numerical analysis carried out in vitro studies are consistent
with the sandwich technique.
- Sandwich techniqueis used in clay soils where have the poor
and weak interaction with the geotextiles.
- given the acceptable development of a factor of safety using
the sandwich technique we can make or design slopes with
more height and slope in the engineering projects.
- sandwich technique in the more heights has more impact in the
factor of safety increase , because of confining pressure increase
and consequently getting better interaction condition between
sand and geotextile .
- The factor of stability safety will be increased, increasing
noumber of reinforced layers in the sandwich technique.
