摘要
通过黏土和砂土的一系列动三轴试验,研究土体永久变形中地震动的有效荷载问题,提出了黏土和砂土应变门槛值与有效荷载幅值下限值的关系,给出了有效荷载幅值的计算公式和有效荷载的推荐值。结果表明,真实地震荷载下土的变形发展与等幅正弦荷载有明显不同,应变发展时程的形态主要受地震动的形态控制。应变门槛值与有效幅值下限值呈非线性关系,应力幅值下限值比应变门槛值大,且在较小的应变门槛值情况下需要比率差别更大的有效幅值才能产生相应的应变。以使土体产生超过总应变10%增量的应力值作为有效荷载幅值,砂土情况下幅值应大于峰值的四分之一,黏土情况下幅值应大于峰值的三分之一。
The effective loads of ground motions for the permanent deformation of soils have been investigated by dynamic triaxial tests on clay and sand, and the relationship between the strain threshold value and the lower limit of the effective amplitude are presented herein. Also, the corresponding calculating formula and the recommended value of effective amplitude are given. The test results indicate that the deformation developments in soils are different for seismic loads and uniform loads. The time history of strain development is mainly controlled by the form of seismic ground motions. The relationship between the strain threshold value and the lower limit of the effective amplitude is nonlinear and the threshold value is larger than the lower limit. In case of small strain threshold value, the effective amplitude of large increasing rate is needed to generate the corresponding strain. The stress generating strain increment of more than 10% of the total strain is taken as the effective amplitude, thus the effective amplitudes need to be larger than one-forth or one-third of the peak amplitudes for sand and clay respectively.
出处
《地震工程与工程振动》
CSCD
北大核心
2009年第5期170-178,共9页
Earthquake Engineering and Engineering Dynamics
基金
中国地震局工程力学研究所基本科研业务费专项(2006B03)
国家重点基础研究发展计划(973计划
2007CB714201)
国家自然科学基金项目(9071501750778165)
关键词
动三轴试验
土体变形
有效荷载
应变门槛值
dynamic triaxial tests
soil deformation
effective loading
strain threshold value
