Strengthening of rock-fill zones of high dams by slushing

Abstract

1. Thanks to their high initial density (porosity less than 20% even if the filler is in the loose state), slushed rock fills have favorable properties in comparison with nonslushed rock fills, independently of the method of filling the voids. 2. Independently of the strength of the original material in the soil skeleton and of the coefficient of coarseness variation of the soil filler, the residual deformations of slushed rock fills usually do not exceed 3% of the value of the vertical pressure. 3. Creep deformations of rock—sand and rock—gravel materials are practically nonexistent even for very high pressures (60–100 kg/cm2); this is of great importance for the prediction of the settlements and horizontal displacements of strengthened rock-fill zones in large dams during the period of operation. 4. The shearing strength of the tested samples, which increased by not less than 10%, is indicative of the increased strength of the slushed rock-fill zones, and shows the possibility of developing several more compact profiles of dams by reducing the number of intermediate berms on the external slopes. 5. When it is necessary to strengthen high-porosity rock fills in regions where there is a sufficient quantity of only gravel—pebble soils, and the construction of the shells is not connected with the need for carrying out the work under severe climatic conditions, successful use can be made also of the method of hydraulic-giant slushing of the voids in thin inclined layers, after preliminary semiproduction tests, for example, for construction of cofferdams.