Shaking Table Tests of Embankment Models Reinforced with Geotextiles - Reinforced Soil Engineering: Advances in Research and Practice - page 398

Table 6 Settlement After Loading

Case Crest (gravel) DV1 Crest (sand) DV1 Berm Berm

1 (unreinforced) 92 38 68 26

2 (sheet) 45 127 45 10

3 (Geogrid) 36 28 24 37

We can from the above information that in the model tests, sheeting had
very little reinforcing effect, while geogrids were able to reduce the deformation
throughout the embankment to a considerable degree. Although it is difficult to
quantify the reinforcement effects in an actual dike based on the model
experiment, we can at least say that, quantitatively speaking, there should be a
large reinforcement effect.
For structures which might undergo liquefaction due to saturation of the
embankment and foundation, we can conclude that geogrids would be a
significant way to increase strength. Since a large amount of money was required
to conduct the large-scale shaking table tests, only Case 2 was considered here,
but from the results of the small model experiment in 3.1.1, we can see that
geogrids played a major role in reinforcing the upper section of the dam.
Therefore, even if we reduce the number of geogrids in Case 2 by half, we should
still be able to expect some strengthening effect. Under actual conditions, this can
help reduce costs (due to fewer geogrids being used), which in turn should help to
bring this method into practical use.
Next, the effects of seismic resistance of geogrids used in an embankment
were investigated in a shaking table test that used a model dike. The results
indicated that geogrids were effective in seismically strengthening structures
whose embankments (sometimes including foundations) were vulnerable to
liquefaction. Furthermore, reinforcement can be especially effective if it is
focused on saturated sections.

4 COMPARISON OF REINFORCED EMBANKMENT MODEL
TESTS WITH GEOGRID AND SOIL IMPROVEMENT

The Nihonkai-Chubu earthquake of 1983 caused damage to about 200 earth
dams, while the Hyogo-Nambu earthquake damaged about 1300 dams. Among
the dams that were most damaged (collapsed or severely incapacitated), some
earth dams probably ruptured due to liquefaction, and their foundations were
restored after the earthquake using cement-type materials. This section examines
two earth dam models that were employed to compare the seismic strengthening