Dynamic Behavior of Cemented Sand and Gravel Material Under Graded Cyclic Loading

In order to study the dynamic characteristics of cemented sand and gravel (CSG) material, a series of tests utilized a dynamic triaxial instrument under cyclic loading were conducted to investigate the mechanical properties and the laws of stress, dynamic modulus and damping ratio with strain evolution, and hereby a new mathematical model of the full dynamic stress-strain curve was founded, the evolution laws for dynamic modulus, damping ratio and dynamic strain were derived from the laws of energy conservation. The results indicated that the CSG material exhibited apparent elasto-plasticity, the compressive strength increase with the increase of confining pressure, the overall enveloping curves were divided into elastic, yield, and failure stages, which can be described by segmental mathematical model. The damage model of specimens was shear failure and had an angle of 48 degrees similar to 53 degrees. There are two stain thresholds for fatigue damage of CSG material under cyclic loading, the thresholds are dividing points of the evolution laws of dynamic modulus and damping ratio, the relationship curves between dynamic modulus and strain were divided 3 phases by the dividing points; and the curves between damping ratio and strain were characterized by U shape and were divided 3 phases by the dividing points.'