An analysis of stress-strain behaviour and wetting effects on quarried rock shells
The analysis of stressstrain behaviour and the effects of submergence on quarried rock shells, used mainly in dams but also in road construction, is of major importance from both economic and safe...
Effect of stress conditions on collapse deformation behavior of a rockfill material
A set of saturated and dry-saturated large-scale triaxial tests were conducted in order to explore the effects of stress conditions on the saturation-induced collapse deformation behavior of a rockfill material. Specimens were tested in different confining pressures and for dry-saturated tests the specimens were submerged in various shear stress levels. The results indicate that in all of the dry-saturated tests a sudden reduction in the volume of the specimens was observed during the submerging process. The ratio of the minimum axial strength of a submerged specimen (at the end of the saturation process) to the shear strength of the specimen before saturation is defined as the coefficient of stress recovery, Csr. Results of the dry-saturated tests showed that this ratio increases as the confining pressure increases and decreases by increasing the shear stress level. According to the results of dry-saturated tests the values of internal friction angle reduction caused by saturation (Δϕc), the ratio of the elasticity modulus of the material after saturation to its elasticity modulus in dry condition, i.e., Ewet/Edry, and also the saturation induced sudden volumetric strain (εvc) decrease as the confining pressure increases. However the shear stress level does not have any meaningful effect on the variation of Dfc, Ewet/Edry and (εvc).
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.