Abstract: Coarse grained soils have been widely used in engineering construction because of the advantages of high shear strength, easy compactability, small deformation and so on. There is still few research on dynamic properties of coarse grained soils, and theoretical research lagged behind the practices. In engineering designs, coarse grained soils were usually regarded as nonliquefiable soils. However, reports of after-earthquake surveys both in China and abroad show that coarse grained soils were serious liquefied. Therefore, under a given earthquake shaking, coarse grained soils with loose to moderate density have much potential to be liquefied. In this study, a Cyclic-mobility constitutive model, which can describe the cyclic-mobility and liquefaction characteristics of soils, was employed to discover the dynamic characteristics of coarse grained soils. On the basis of model parameters calibration, the different influencing factors which affecting dynamic properties of coarse grained soils were further studied, such as the friction between loading plates and specimen, gravitational force of specimen, cyclic shear ratio, confining pressure and loading frequency. The results show that Cyclic-mobility constitutive model can well reproduce the stress-strain characteristics of coarse grained soils under undrained triaxial test, gravitational field and the friction between loading plates and specimen have some effects on the laboratory element test results of coarse grained soils. Under lower confining pressure or higher cyclic shear stress ratio, the phenomenon of larger dynamic strain and the uneven distribution of dynamic strain inside samples will be more obvious. The distributions of volumetric strain inside samples are similar under lower loading frequencies, however, the combined action of high loading frequency and cyclic shear stress ratio will cause large damage on the sample. In the triaxial test, when studying the dynamic response of soil elements at different locations by triaxial test, attention should be paid to the arrangement of strain sensors, and the results should be considered comprehensively and corrected appropriatel.

Key words: coarse grained soils, dynamic characteristics, numerical simulation, cyclic-mobility constitutive model