1610
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Fig. 5 compares the maximum crest displacement of the dam
section without (solid lines) or with (dashed lines) provision of
Geosynthetics. It can be noted that with provision of
Geosynthetics the displacement of the crest is almost reduced to
one third. The reason for this drastic reduction in crest
displacement (with provision of Geosynthetics as a seepage
barrier) owns to the fact that dam body is not experiencing the
excess pore pressure during dynamic loading.
4.2.2
Acceleration – time history of earthquake data
Dynamic numerical analysis of the earthen dam section
(without and with provision of Geosynthetics) is performed
utilizing the acceleration-time history record of the available
26
th
January 2001 Bhuj earthquake data (Iyenger and Raghu
Kanth, 2006) as well as five other major earthquakes, i.e., El
Centro, North ridge, Petrolia, TAFT, Loma Prieta that occurred
in the past (total six). By doing so it was possible to examine
the stability of the dam section under different levels of
amplitudes, frequency and time duration. Detailed information
about the characteristics of these major earthquakes is available
in Srivastava (2010). For detailed discussion on the method of
analysis under earthquake loading condition, reader may refer to
the reference manual of the software tool.
Table 1 summarizes the maximum crest displacement of
the dam section under different circumstances. It can be noted
that provision of Geosynthetics, when used as a seepage barrier,
greatly reduces the deformation of the crest.
Table 1 Comparison of maximum x-crest displacement of dam
section under different earthquake loading
Famous
EQ
Maximum x-crest displacement
Without
Geosynthetics
With
Geosynthetics
Bhuj
EQ
0.187
0.056
EL Centro
0.232
0.087
North Ridge
0.764
0.232
Petrolia
0.880
0.209
TAFT
EQ
0.302
0.120
Loma Prieta
EQ
0.548
0.194
5 CONCLUSIONS
Use of Geosynthetics as seepage barrier not only control the
seepage losses but also enhances the stability of the dam section
under static as well as dynamic conditions. Under static
condition the factor of safety is increased 1.45 times and under
dynamic loadings deformation of the crest of the dam section
reduces to almost 3 times and the crest acceleration is reduced
to 2.5 times.
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Figure 5 Comparison of maximum crest displacement of
the dam section without and with provision of
Geosynthetics