Evaluation of failure and deformation in alluvial clay deposits during earthquake

地震期间冲积粘土沉积物破坏和变形的评估

基本信息

批准号：
06650545
负责人：
HYODO Masayuki
金额：
$ 1.28万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650545/
关键词：
earthquake clay initial shear stress dynamic strength pore pressure residual deformation dynamic stability analysis 塑性指数過圧密比

项目摘要

Although there exists relatively clear guide line on the liquefaction behavior of sands, a similar knowledge base for clays under cyclic loading needs to be developed, particularly for in-situ conditions. For the purpose of this research program thin walled clay samples have been taken from Hiroshima, Yokohama, Kumamoto, Ooita and Saga. The properties of the clays depend not only on characteristics such as their plasticity but also their sedimentary origins, fabric and stress path. A series of cyclic triaxial tests has been performed at varying plasticity indeces, overconsolidation ratios and confining pressures on undisturbed samples. These have heen compared with a further series of tests on remolded clays. As a result we have developed an empirical equation relating cyclic shear strength to the plasticity index, overburden pressure, consolidation yielding stress and overconsolidation ratio.Additionally, a series of undrained cyclic triaxial compression tests has been performed on a high plasticity marine clay. Testing was performed using various combinations of initial static and subsequent cyclic shear stress on isotropically and anisotropically consolidated specimens. The cyclic shear strength was considered first, and then, the accumulated shear strain was investigated related to the effective stress ratio at the peak cyclic stress. Based on the experimental results, a semi-empirical model is proposed for evaluating the development of pore pressure and residual shear strain during cyclic loading. The model successfully explains the behavior of clay subjected to various magnitudes of initial static and subsequent cyclic shear stresses.

尽管关于砂的液化行为存在相对明确的指导方针，但需要开发循环荷载下粘土的类似知识库，特别是对于现场条件。出于本研究计划的目的，从广岛、横滨、熊本、大分和佐贺采集了薄壁粘土样品。粘土的特性不仅取决于其可塑性等特征，还取决于其沉积起源、结构和应力路径。在不同的塑性系数、超固结比和未扰动样品的围压下进行了一系列循环三轴试验。这些已与重塑粘土的进一步系列测试进行了比较。因此，我们建立了一个将循环剪切强度与塑性指数、上覆压力、固结屈服应力和超固结比联系起来的经验方程。此外，还对高塑性海相粘土进行了一系列不排水循环三轴压缩试验。使用初始静态和随后的循环剪切应力的各种组合对各向同性和各向异性固结样本进行测试。首先考虑循环剪切强度，然后研究累积剪切应变与峰值循环应力处的有效应力比的关系。基于实验结果，提出了一个半经验模型来评估循环加载过程中孔隙压力和残余剪应变的发展。该模型成功地解释了粘土在承受各种强度的初始静态应力和随后的循环剪切应力时的行为。