Sealing Leakage of Earth Dam by Concrete Diaphragm

Some seriously cracked and leaked earth dams in China have been successfully strengthened by the cast-in-situ concrete diaphragm at or near the dam axis through the dam embankment. The diaphragm is enabled to seal the leakage through concentrated seepage path in the earthfill resulted from the large voids or the cracks in cohesive earthfill as well as the leakage through the alluvium in dam foundation. The effectiveness of this strengthening method depends on the correct determination of the major seepage channels. Serious longitudinal cracks have occurred in some dams during excavating the slurry trenches and pouring concrete into them owing to the hydraulic fracturing effect of the drilling fluid and liquid concrete. After some modification of the construction technique the strengthening work was carried out smoothly. The cracks were closed after completion of construction work and the contact between the earthfill and diaphragm was satisfactory