Evolution of anisotropic stiffness and damping ratio of soft clay by bidirectional step-amplitude cyclic triaxial tests

IF 5.7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Acta Geotechnica Pub Date : 2025-05-21 DOI:10.1007/s11440-025-02620-z

Zhong-Liang Zhang, Zhen-Dong Cui, Wen-Xiang Yan

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Abstract

Soft clay is the primary soil type encountered in engineering construction in the eastern coastal regions of China. The deformation characteristics of soft clay are closely related to its inherent stiffness. Under the action of long-term geostatic stress and external load, the dynamic behavior and characteristics of soil in vertical and horizontal directions are different, i.e., anisotropy. In this study, the dynamic parameters of saturated soft clay samples were investigated through bidirectional dynamic step-amplitude cyclic triaxial experiments. The anisotropic stiffness evolution of soft clay over a wide strain range was analyzed, and the effects of different consolidation states on the development of dynamic shear modulus and damping ratio were also examined. Under the same confining pressure, the soft clay samples subjected to axial step-amplitude cyclic loading exhibited higher ultimate dynamic stress values in backbone curves compared to those under radial step-amplitude cyclic loading, while the obtained shear modulus showed the opposite trend. The anisotropic stiffness ratio of soft clay samples tended to increase with increasing confining pressure, with an average value of 1.25 in the range of 100–300 kPa. The shear modulus of the samples increased with increasing confining pressure and consolidation stress ratio but decreased with increasing overconsolidation ratio (OCR).

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双向阶幅循环三轴试验研究软粘土各向异性刚度和阻尼比的演化规律

软土是中国东部沿海地区工程建设中遇到的主要土型。软黏土的变形特性与其固有刚度密切相关。在长期地静力和外荷载作用下，土的动力行为和特征在垂直方向和水平方向上是不同的，即各向异性。通过双向动态阶幅循环三轴试验，研究了饱和软粘土试样的动态参数。分析了软土在大应变范围内的各向异性刚度演化规律，研究了不同固结状态对软土动剪模量和阻尼比发展的影响。在相同围压下，轴向阶跃幅值循环加载的软粘土试样在骨干曲线上的极限动应力值高于径向阶跃幅值循环加载的软粘土试样，而得到的剪切模量则相反。软粘土各向异性刚度比随围压的增加呈增大趋势，在100 ~ 300 kPa范围内平均值为1.25。剪切模量随围压和固结应力比的增大而增大，随超固结比的增大而减小。

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来源期刊

Acta Geotechnica ENGINEERING, GEOLOGICAL-

CiteScore

9.90

自引率

17.50%

发文量

297

审稿时长

4 months

期刊介绍： Acta Geotechnica is an international journal devoted to the publication and dissemination of basic and applied research in geoengineering – an interdisciplinary field dealing with geomaterials such as soils and rocks. Coverage emphasizes the interplay between geomechanical models and their engineering applications. The journal presents original research papers on fundamental concepts in geomechanics and their novel applications in geoengineering based on experimental, analytical and/or numerical approaches. The main purpose of the journal is to foster understanding of the fundamental mechanisms behind the phenomena and processes in geomaterials, from kilometer-scale problems as they occur in geoscience, and down to the nano-scale, with their potential impact on geoengineering. The journal strives to report and archive progress in the field in a timely manner, presenting research papers, review articles, short notes and letters to the editors.