中文摘要：

基于线性规则波浪作用下有限厚度海床动力响应的解析解,证明了非饱和、各向异性海床中一点土体单元上由主应力轴旋转所引起的应力路径应为非标准椭圆形而不是传统认知的圆形,并推导了量化该非标准椭圆形应力路径大小和形状的3个特征参数。通过27组不排水条件下的循环主应力轴旋转试验,讨论了轴向偏差应力和剪应力的幅值及初始相位差对饱和砂土动强度的影响。试验结果表明轴向偏差应力对动强度的影响高于剪应力的影响,同时初始相位差对动强度的影响显著。随着初始相位差的增大,破坏周次的对数基本呈线性减小,进而得出了非标准椭圆形和标准椭圆形两种应力路径下砂土动强度的关系。研究成果克服了传统圆形应力路径下土体动强度特性难以直接用于分析有限厚度海床稳定性的不足,可为近海海洋工程设计提供技术支持。

英文摘要：

Based on the analytical solutions for wave-induced soil response in an unsaturated hydraulically anisotropic seabed of finite thickness, a nonstandard elliptical, i.e., non-circular, rotation stress path is proven to be a more common state in a soil element due to the linear regular wave loads. Three characteristic parameters that determine the size and shape of the nonstandard elliptical rotation path are deduced. Using twenty-seven groups of undrained cyclic principal stress rotation tests, the effects of the amplitude and the initial phase difference of the normal stress difference and shear stress on the cyclic strength of saturated sand are studied. The experimental results show that the normal stress difference plays a more important role in the cyclic strength than the shear stress, and the influences of the initial phase difference on the cyclic strength are significant. The logarithmic failure cycles show an approximately linear decrease with the increasing initial phase difference, and therefore the relation of dynamic strength under two kinds of elliptical rotation stress paths, i.e., nonstandard and standard, is derived. This experimental research overcomes the drawback that the shear characteristics of sand for the traditional circular rotation stress path cannot be directly used to analyze the stability of a finite seabed, and the conclusion may provide a technical support for the design of coastal and offshore engineering.