Abstract:
Seepage control in earthen dam and embankment is one of the most challenging
issues in Geotechnical Engineering. An effective measure to reduce and control the
seepage in the context of alluvial soil characteristics in Bangladesh may be
permeation grouting, whereby, seepage of permeant-fluid in horizontal direction is the
common phenomenon rather than that of vertical direction. As such, it is desirable to
emphasize horizontal controlling of seepage. The main objective of this study was to
examine the phenomenon of permeation grouting due to horizontal infiltration of
grouts and to measure the strength performance of grouted soil.
In this study, a test program was conducted using a specially prepared permeameter
and water-bentonite grout suspension. A series of tests was carried out in order to
determine the appropriate grout suspension for an effective control of seepage through
pores of granular soil medium. Tests were carried out for both horizontal and vertical
directions of flow of grout suspension. Besides, direct shear tests were conducted to
investigate the strength properties of sandy soil sample. In a view to assess
permeation characteristics during the grout operation, different parameters like
injection time to stop grout flow, injected grout weight, penetration distance for
various bentonite concentration were measured and the time dependent flow rate
variation was also monitored. Appropriate range of bentonite concentration and the
optimum doze within the range was investigated.
The experimental study showed that the appropriate range of bentonite concentration
for the sandy soil sample is 1% to 3% considering the grouting parameters like
injection time, injected grout weight, penetration distance etc. It is found that as per
laboratory tests, 2.5% grout concentration may be considered as the optimum doze of
grouting. Direct shear tests on the grouted soil sample provided very little indicative
results of increasing shear strength by bentonite grouting operation.
