STUDY ON IMPERMEABLE CONSTRUCTION METHODS USING BENTONITE MIXED SOIL IN RESERVOIRS

Abstract

The use of bentonite is one of the solutions to compensate for the lack of clay used in the impermeable layer of reservoirs. We conducted mixing tests of bentonite-mixed soil and confirmed that the addition of bentonite to the base soil improved the imperviousness. Moreover, it was confirmed that the imperviousness of the bentonite-mixed soil was correlated with the swelling power of the bentonite, the amount of bentonite added, and the density. A reservoir was constructed using a bentonite mixture soil of the determined mix as the impermeable layer. The “vertical impervious wall method” and the “thin layer step cut method” were used for the impermeable construction method installed in the embankment. Observation wells were installed downstream of each embankment, and water levels were measured continuously after construction. The infiltration lines for each impermeable construction methods were predicted from the water level data. It was confirmed that the position of infiltration line was sufficiently lowered by the impermeable layer using bentonite-mixed soil in both methods.