细粒含量和相对密度对饱和珊瑚砂体应变发展特性影响试验

Experimental Study on the Characteristics of Volumetric Strain Generation in Saturated Coral Sand:Effect of Fines Content and Density

随着珊瑚岛礁基础设施建设的不断发展,其工程应用的安全性已成为学术界重点关注的问题。通过系列排水循环三轴试验,探究细粒含量F_(c)和相对密度D_(r)对饱和珊瑚砂变形特性的影响。试验表明:F_(c)和D_(r)均会显著影响累积体应变ε_(vd,ir)^(N)(N为加载过程中的循环次数)和动弹性模量E_(d,N)的发展。当0%≤F_(c)≤30%时,不同工况下试样变形的发展模式依据安定性理论可描述为塑性安定行为。稳态累积体应变ε^(s)_(vd,ir)随F_(c)的增大而增大,随D_(r)的增大而减小;ε^(N)_(vd,ir)的发展速率随F_(c)的增大而增大。此外,F_(c)的增大会导致初始动剪切模量E_(d,l)和稳态动弹性模量E_(d,s)产生一定幅度衰减,引入无量纲参数相对动弹性模量E_(r),发现E_(r)的增长速率随F_(c)的增大而增大,但几乎不受D_(r)的影响。基于二元介质理论引入等效骨架孔隙比e^(*)_(sk),鉴于稳态累积体应变ε^(s)_(vd,ir)、E_(d,l)和E_(d,s)均与e^(*)_(sk)存在相关性,建立饱和珊瑚砂ε^(N)_(vd,ir)/ε^(s)_(vd,ir)和E_(r)与e^(*)_(sk)相关的预测模型,结合文献中数据进一步验证模型的适用性。

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(F_(c))and the relative density(D_(r))on the deformation properties of saturated coral sand has been explored through a series of drained cyclic triaxial tests.An important finding is that F_(c) and D_(r) considerably affect the development of cumulative volumetric strain(,ε^(N)_(vd,ir))and dynamic elastic modulus(E_(d,N)).When F_(c) 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(,ε^(N)_(vd,ir))increases with the F_(c) and decreases with D_(r).Furthermore,the development rate of increases with the F_(c).Another notable finding is that the increase in the F_(c) leads to a certain decay in the initial dynamical shear modulus(Ed,1)and the steady-state dynamical elastic modulus(E_(d,s)).The relative dynamic elastic modulus(E_(r))is a dimensionless parameter introduced to characterize the development of E_(d,N) with N.It is found that the growth rate of E_(r) increases with the F_(c) while being independent of D_(r).The equivalent skeleton void ratio()is introduced based on the binary medium theory.It is observed that there is a power-function growth trend in (N)_(vd,ir)/ε^(s)_(vd,ir)with the increase in,while Ed,1 and Ed,s decrease linearly with the increase in e^(*)_(sk).A predictive model between,ε^(N)_(vd,ir)/ε^(s)_(vd,ir),E_(r),and e^(*)_(sk)is established,and its applicability is verified based on data from the literature.