Application of cement grouting for stabilization of coarse materials

In a rare engineering experience throughout the world, we successfully stabilized relatively coarse materials of drain using cement grouting. The grouting work was performed at the Karkheh earth dam, southwest Iran, and was part of the efforts to extend the dam's 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 cut-off wall wall was trenching and execution of plastic-concrete wall through the relatively coarse materials of drain in the dam body. Due to high permeability of drain, the work was associated with the possible risk of excessive slurry loss which could result in the collapse of the trench. In order to achieve an appropriate grouting plan and to determine the mix ratio for the grouting material, a full-scale test platform consisting of actual drain materials was constructed and underwent various tests. Results of the testing program revealed that a grouting plan with at least 2 grouting rows and a Water/Cement mix ratio of 1/(1.5-2) can successfully stabilize the drain materials. After finalizing the technical characteristics of the grouting work, the method was applied on the drain materials of the Karkheh dam body. The results were satisfactory and the drain materials were stabilized successfully so that the cut-off wall was executed without any technical problem.