Effect of the grain-size composition and method of compaction on the density of coarse rubble in a talus

Conclusions

• 1. The density of coarse-grained material in a talus is governed by the grain-size composition and method of compaction; a quantitative estimate of the effects of these factors is made by means of the coefficient of relative density r and the degree of compaction \gn.

• 2. A representation of the grain-size curves of real coarse-grained material and laboratory mixtures of rubble in relative units (Fig. 2) is the basis for making models; the scale of the model is determined by the ratio of the grain sizes of the individual fractions of the natural material and the rubble in the model mixtures.The use of models enables us to determine the main physicomechanical parameters of the mixtures, which govern the choice of a rational method of obtaining the material with the required grain-size composition, the assignement of optimum grain-size composition from the condition of obtaining the greatest talus density in the dam, the choice of a rational method of laying and compacting the material, the control of the density of the material laid in the body of the dam, and finally, estimation of the grain-size composition of all the coarse-grained material worked in the hydroelectric station with the aim of use in useful fillings.

• 3. In selecting a method of compacting coarse-grained materials with rational grain-size composition giving high talus density, it is recommended that account should be taken of the possibility of additional compaction due to consolidation of the structure and the action of passing transport during laying of the material in thinlayers.