Abstract The stress-strain-strength response of soils is of significant interest to development and calibration of realistic constitutive models that can be used in numerical simulation of geotechnical engineering problems. An extensive characterization of Ottawa F65 sand along with various monotonic and cyclic tests conducted during the course of the Liquefaction Experiments and Analysis Projects (LEAP) are presented here. The specimens in these tests were prepared using a meticulous sample preparation technique to facilitate their consistency and repeatability. Monotonic drained and undrained triaxial tests shed light on the steady-state (critical state) of Ottawa sand, while stress-controlled and strain-controlled cyclic triaxial and direct simple shear tests provide key information on the cyclic stress-strain behavior and liquefaction strength of this soil. The triaxial tests identify the liquefaction strength of the soil at different densities, while the direct simple shear tests evaluate the effect of overburden pressure on the cyclic response. The results of these experiments are also compared to the experimental results available in the literature. The data obtained from the cyclic triaxial and direct simple shear tests were further analyzed by plotting the computed shear modulus degradation and damping curves. The results show how the soil stiffness degrades as cyclic shear stress is applied for soil at different densities and confining stresses. It can be seen that the rate of shear modulus degradation increases with the increase of confining stress and decreases with the increase of soil density. The damping curves consistently show an increasing in damping ratio until a shear strain of about 0.05%, followed by a plateau at about 20–25% damping ratio for shear strain between 0.05 and 0.5%, and ending with a decrease in damping until reaching a final damping ratio of about 10%.

中文翻译：

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渥太华F65砂的应力应变行为及液化强度特性

摘要 土壤的应力-应变-强度响应对于可用于岩土工程问题数值模拟的真实本构模型的开发和校准具有重要意义。此处介绍了渥太华 F65 砂的广泛表征以及在液化实验和分析项目 (LEAP) 过程中进行的各种单调和循环测试。这些测试中的样品是使用细致的样品制备技术制备的，以促进其一致性和可重复性。单调排水和不排水三轴试验揭示了渥太华砂的稳态（临界状态），而应力控制和应变控制的循环三轴和直接简单剪切试验提供了有关该土壤循环应力-应变行为和液化强度的关键信息。三轴试验确定不同密度下土壤的液化强度，而直接简单剪切试验评估上覆压力对循环响应的影响。这些实验的结果也与文献中可用的实验结果进行了比较。通过绘制计算出的剪切模量退化和阻尼曲线，进一步分析了从循环三轴和直接简单剪切试验中获得的数据。结果表明，当对不同密度和围压的土壤施加循环剪应力时，土壤刚度是如何降低的。可以看出，剪切模量退化率随着围压的增加而增大，随着土体密度的增加而减小。阻尼曲线始终显示阻尼比增加，直到剪切应变约为 0.05%，然后在 0.05% 和 0.5% 之间的剪切应变的阻尼比达到约 20-25% 时达到平稳状态，并以阻尼下降结束，直到达到最终阻尼比约为 10%。