Abstract

Marine sandy soils may liquefy under wave loading and/or seismic loading. Current research shows that the presence of fines can significantly affect the liquefaction potential of sandy soils. Thus, a quantitative evaluation of the effect of fines on the undrained behavior of sandy soils can provide useful information on soil liquefaction that can advance the design of foundations of coastal structures. However, little is known about how the grain size of nonplastic fines affects the mechanical behavior of sandy soils. In this study, a series of strain-controlled monotonic undrained triaxial compression tests and critical-state constitutive modeling are carried out on a medium dense saturated sandy soil for various fines contents (FCs), mean grain sizes ($d_{50}^{\mathrm{f}}$ s) of nonplastic fines, and initial effective confining pressures. The results show that the peak deviatoric stress decreases significantly with decreasing $d_{50}^{\mathrm{f}},$ especially for high FCs. The equivalent granular state parameter (ψ*) at the phase transformation can be used to characterize the effect of fines on the dilatancy of sandy soils in constitutive modeling. Additionally, the initial value of ψ*(${\psi }_0^{*}$) serves as physical index for characterizing the influence of fines on the undrained instability state of sandy soils.

摘要

海洋砂质土壤在波浪载荷和/或地震载荷下可能会液化。目前的研究表明，细粒的存在会显着影响沙质土壤的液化潜力。因此，对细粒对沙质土壤不排水行为的影响的定量评估可以提供有关土壤液化的有用信息，可以推进沿海结构地基的设计。然而，关于非塑性细粒的粒度如何影响砂质土壤的力学行为知之甚少。在本研究中，对不同细粒含量 ( FC s)、平均粒度 ($d_{50}^{\mathrm{F}}$s) 非塑性细粒和初始有效围压。结果表明，峰值偏应力随着减小而显着减小。$d_{50}^{\mathrm{F}},$特别是对于高FC s。相变时的等效颗粒状态参数 ( ψ *) 可用于表征细粒对本构模型中砂土剪胀的影响。此外，ψ *(${\psi }_0^{*}$) 作为表征细粒对沙质土壤不排水不稳定状态影响的物理指标。