Trial Chemical Grouting in Filter Materials at the Karkheh Dam Site, Iran

A sodium silicate-based chemical grout was used in the Karkheh dam site in order to examine the performance of the chemical grouting technique for stabilization of the dam's filter material. Karkheh, an embankment dam with the reservoir capacity of about 7.4 billion cubic meter at the maximum water level, is the largest dam in Iran. The grouting works performed at the dam site, were part of the prerequisites for development of the dam's complementary cut-off wall. Since the dam was completed, the execution of the new cut-off wall from the dam crest was inevitable. Hence, one of the main difficulties associated with the development of the new wall was trenching and execution of plastic concrete wall through filter materials of the dam body. To resolve this technical problem, the method of chemical grouting was employed. However, the process was so challenging since little research work has been devoted to the application of grouting technique in filter. Wide testing program including full scale tests were performed to obtain optimized mix design and grouting program. A full scale platform consisting actual filter materials was constructed and undergone various tests. Results of the testing program revealed that a chemical grout consisting of sodium silicate, water, and ethyl acetate with proper mix ratio can successfully stabilize the filter of the dam body.