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A new chemical grouting method has been developed for conglomerate formations based on the experimental studies. Due to the lack of chemical grouting experience of conglomerate formations, the testing programs were performed to evaluate the performance of chemical grouting in the water sealing of part of conglomerate foundation of Karkheh earth dam using a combination of field and laboratory tests. First, the chemical grouts alone were examined with regard to viscosity-time behavior, gelation time, temperature-influence, stability, and deformability. These laboratory tests, led to the selection of the final chemical grout which was a solution of sodium silicate, water, and ethyl acetate as reactant. The second step tested grout-soil interaction: The injectability and permeability reduction of the selected chemical grout was examined in field injection tests. In this step two field tests were performed including shallow test holes without hydrostatic pressure and full scale tests under dam real hydrostatic pressure head. Based on these two field injection tests, performed in the conglomerate foundation of Karkheh dam, a new chemical grouting method for conglomerate formations is proposed and satisfactory results led to the recommendation of this method for eventually successful application.

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The effects of cementation and the physical properties of grains on the shear behavior of grouted sands are investigated in this

paper. The consolidated-undrained triaxial shear behavior of three grouted carbonate sands with different physical properties,

including particle size distribution, particle shape and void ratio, was studied. Two sands were obtained from the north shores

of the Persian Gulf, south of Iran, called Hormoz and Kish islands sands, and one sand was obtained from the south beaches

of England and called Rock beach sand. The selected sands were grouted using a chemical grout of sodium silicate and tested

after one month of curing. Test results showed that the effect of bonding on the shear behavior and strength depends on the bond

strength and confining pressure. In addition, the shear behavior, yield strength and shear strength of grouted sands under

constant conditions, including the initial relative density, bonds strength, confining pressure and loading, were affected by the

physical properties of the sands. Furthermore, the parameters of the Mohr-Coulomb shear strength failure envelope, including

the cohesion and internal friction angle of grouted sands under constant conditions, were affected by the physical properties

and structure of the soils.

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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 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.