Stabilizing Constructed Masonry Dams by Means of Cement Injections

The title of this paper carries the implication of many difficulties, which to a gratifying degree were surmounted in the process described. In scope the work embraced three principal gravity dams of rubble masonry, faced with ashlar, aggregating 14 000 ft in length and ranging from 30 ft to 190 ft in height. These structures, situated in the Western Ghauts of India, about sixty miles inland from Bombay, at 2 200 ft above sea level, have been in use since about 1917 for the storage of water for hydro-electric development under the available head of 1 700 ft. In recent years the increase of seepage through and under the dams gave rise to some apprehension as to their continued stability, and the remedy of cement injections was prescribed by a committee of consulting engineers.

Accordingly, the paper describes the methods and results of the borings and the injection of 64 000 bbl of Portland cement into 380 000 lin ft of drill holes in the three dams, working under full reservoir conditions. Incidentally, observation of the process during 2½ yr seems pertinent to the currently moot questions of gravity dam design, particularly as to the uplift and sliding influences, and as to reliance upon the usual assumptions of a monolithic structure.