MECHANICAL PROPERTIES OF ROCKFILL

Definitions are presented of parameters that describe quantitatively the solid phase of a granular mass. These parameters are used in the evaluation of contact forces. The theoretical aspects are examined of the forces between grains as a function of effective stress and the parameters that describe the grain skeleton. The analysis and measurement is described of particle breakage, which is a function of the contact forces and the crushing strength of the particles. The devices developed to investigate the shear strength and stress-strain characteristics of rockfills and the techniques for preparation of specimens are described, as well as the measurement of shear strength of rockfill in the triaxial and plane-strain apparatus. The effects of grain breakage and characteristics of the grain skeleton, and the type of test are discussed. Consideration is given to the theory of failure, and the evaluation of the frictional resistance of a granular soil and development of a general criterion for failure are set forth. The measurement of stress-strain characteristics by means of one-dimensional and triaxial compression tests, and analysis of the time settlement curves by oedometer tests are described. Stress-strain relationships based on the study of contact forces and the determination of the frictional resistance are presented. Conclusions and recommendations for selecting rockfill material and estimating their properties is also presented.