Horizontal infiltration of grouts and its effect on shear strength of sandy oil

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.