工程科学与技术 (Nov 2024)
Experimental Study on the Characteristics of Volumetric Strain Generation in Saturated Coral Sand: Effect of Fines Content and Density
Abstract
With the ongoing construction of military and civilian infrastructure, the safety of infrastructure in Nansha Reef and offshore marine areas in the South China Sea has become a major concern. 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 Fc and Dr considerably affect the development of cumulative volumetric strain ($ \varepsilon_{\text{vd},\text{ir}}^N $) and dynamic elastic modulus (Ed,N). When Fc is less than the threshold fines content, the developmental pattern of specimen deformation can be described using the stability theory as a plastic stability behavior. Steady-state cumulative volumetric strain ($ \varepsilon_{\text{vd},\text{ir}}^{\mathrm{s}} $) increases with the Fc and decreases with Dr. Furthermore, the development rate of $ \varepsilon_{\text{vd},\text{ir}}^N $ increases with the Fc. Another notable finding is that the increase in the Fc leads to a certain decay in the initial dynamical shear modulus (Ed,1) and the steady-state dynamical elastic modulus (Ed,s). The relative dynamic elastic modulus (Er) is a dimensionless parameter introduced to characterize the development of Ed,N with N. It is found that the growth rate of Er increases with the Fc while being independent of Dr. The equivalent skeleton void ratio ($e_{{\text{sk}}}^*$) is introduced based on the binary medium theory. It is observed that there is a power-function growth trend in $ \varepsilon_{\text{vd},\text{ir}}^{\mathrm{s}} $with the increase in $e_{{\text{sk}}}^*$, while Ed,1 and Ed,s decrease linearly with the increase in $e_{{\text{sk}}}^*$. A predictive model between $ \varepsilon_{\text{vd},\text{ir}}^N/\varepsilon_{\text{vd},\text{ir}}^{\mathrm{s}} $, Er, and $e_{{\text{sk}}}^*$ is established, and its applicability is verified based on data from the literature.
