Abstract Lacustrine soils from the former Texcoco Lake within the Basin of Mexico, some 14 km north of Mexico City, have unique geotechnical properties. These materials have been thoroughly studied in the past, and yet, very few investigations have addressed the issue of the anisotropy of their shear stiffness modulus at very small strain levels (G0). Stiffness anisotropy, even at very small deformations, may significantly influence the response of the soil in a variety of cases and applications including soil-structure interaction problems under static and dynamic conditions. In this study, a large-size oedometer equipped with bender elements was used to measure the shear wave velocities along different paths as an indirect assessment of G0. The initial or inherent anisotropy of the materials was evaluated with these measurements. The experimental results revealed that the stress-induced anisotropy was not significant; hence, the shear stiffness modulus was seen to depend mainly on the initial anisotropy. An inverse correlation between the yield stress (σ’y) (or over-consolidation ratio, OCR) and the initial anisotropy was found, whereas a direct correlation between the liquidity index and the initial anisotropy was also disclosed.

中文翻译：

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配备弯曲元件的大型固结仪中湖相土壤的各向异性

摘要 位于墨西哥城以北约 14 公里的墨西哥盆地前特斯科科湖的湖相土壤具有独特的岩土工程特性。过去对这些材料进行了彻底的研究，然而，很少有研究解决在非常小的应变水平 (G0) 下它们的剪切刚度模量的各向异性问题。刚度各向异性，即使在非常小的变形下，也可能显着影响土壤在各种情况和应用中的响应，包括静态和动态条件下的土壤-结构相互作用问题。在这项研究中，配备有弯曲元件的大型固结仪用于测量沿不同路径的剪切波速度，作为 G0 的间接评估。通过这些测量评估材料的初始或固有各向异性。实验结果表明，应力引起的各向异性不显着；因此，剪切刚度模量主要取决于初始各向异性。发现屈服应力 (σ'y)（或超固结率，OCR）与初始各向异性之间呈负相关，同时还披露了流动性指数与初始各向异性之间的直接相关性。