Dynamic deformation characteristics of saturated coral sand incorporating fines content under drained conditions

Abstract

The effect of the fine content (FC) and the relative density (Dr) on the deformation properties of saturated coral sand has been explored through a series of drained cyclic triaxial tests. An important finding is that both FC and Dr significantly affect the development of cumulative volumetric strain (εvd,irN) and dynamic elastic modulus (Ed,N). Steady state cumulative volumetric strain (εvd,irs) increases with FC and decreases with Dr. When FC increases from 0 % to 30 %, the increment in εvd,irs is about 0.69 %, 0.41 %, 0.16 % under Dr=30 %, 45 %, 70 %, respectively. Furthermore, the development rate of εvd,irN increased with FC. Another significant finding is that the increase of the FC leads to a certain decay of the initial dynamical shear modulus (Ed,1) and the steady state dynamical elastic modulus (Ed,s). When FC increases from 0 % to 30 %, the reduction in Ed,1 is about 16.38 MPa, 12.39 MPa, 10.31 MPa and the reduction in Ed,s is about 6.96 MPa, 5.44 MPa, 3.24 MPa under Dr = 30 %, 45 %, 70 %, respectively. A dimensionless parameter, the relative dynamic elastic modulus (Er), is introduced to characterize the development of Ed,N with N. It is found that the growth rate of Er increased with FC, but it is independent on Dr. The equivalent skeleton void ratio (esk*) was introduced based on the binary medium theory. It is found that εvd,irs shows a power-function growth trend with an increase in esk*, while Ed,1 and Ed,s decrease linearly with the increase of esk*. A predictive model between εvd,irN/εvd,irs, Er, and esk* was established, and the applicability of the model was verified based on data from the literature.

Keywords

• Coral sand
• Fine content
• Density relative
• Cumulative volumetric strain
• Dynamic elastic modulus