非等向固结条件下含砾粒珊瑚土动力液化特性试验研究

    Cyclic liquefaction behavior of coral sand-gravel soil under anisotropic consolidation conditions

    • 摘要: 实际珊瑚岛礁工程中,吹填材料多为含砾粒的宽级配砂砾性土,且通常处于非等向固结应力状态。为研究含砾粒珊瑚土在不同固结条件下的动力液化响应,开展了一系列不排水动三轴-弯曲元联合试验。结果表明,相比于等向固结试样所呈现的循环活动性响应,非等向固结珊瑚土的动力液化破坏多由残余变形累积导致,且初始静偏应力的存在不同程度上减缓了孔压累积趋势,进而提高了土体的抗液化强度。此外,不同初始静偏应力和有效围压条件下,珊瑚土归一化最大剪切模量与抗液化强度之间存在近似唯一的关系,表明基于最大剪切模量或剪切波速的抗液化能力评价方法对珊瑚土具有较好的适用性。

       

      Abstract: The wide-graded coral sand-gravel soil is commonly used as filling or foundation materials in onshore and offshore engineering projects and often under anisotropic stress conditions. A series of undrained cyclic loading tests are conducted using a testing system combined with triaxial apparatus and bender element to investigate the cyclic liquefaction response of coral soil under various consolidation conditions. The results indicate that compared to the isotropically consolidated specimens that exhibit cyclic mobility response, the anisotropically consolidated coral soil usually fails due to the excessive accumulation of residual deformation. Moreover, the presence of the initial static deviatoric stress slows down the pore pressure buildup, thereby increasing the resistance of soils to cyclic liquefaction. An approximately unique relationship is observed between the normalized maximum shear modulus and the liquefaction resistance of coral soil with varying static deviatoric stresses and effective confining pressures, suggesting that the evaluation methods based on the maximum shear modulus or shear wave velocity are highly suitable for assessing the liquefaction potential of coral soil.

       

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