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中南大学学报(自然科学版)

Journal of Central South University

第46卷    第6期    总第250期    2015年6月

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文章编号:1672-7207(2015)06-2309-08
波浪荷载作用下原状软黏土动力特性和基于能量方法的孔压研究
杨彦豪1, 2,周建1, 2,温晓贵1, 2,严佳佳1, 2,曹洋1, 2

(1. 浙江大学 滨海和城市岩土工程研究中心,浙江 杭州,310058;
2. 浙江大学 软土与环境土工教育部重点实验室,浙江 杭州,310058
)

摘 要: 针对杭州原状软黏土,利用浙江大学5 Hz空心圆柱扭剪仪进行等向固结条件下的主应力轴旋转试验以研究波浪荷载作用下软黏土的动力特性。探讨不同频率和循环应力比条件下土体的应变发展、模量衰减等动力特性。采用能量方法,研究频率和循环应力比对孔隙水压力与损耗能关系的影响,并对不同条件下土体的崩塌能进行对比分析。研究结果表明:在主应力轴旋转条件下,原状软黏土存在一个门槛循环应力比,当循环应力比小于该值时,应变只在较小范围内发展,土体模量呈“急剧—平稳”的衰减规律;当循环应力比大于该值时,应变曲线会因土体达到结构崩塌而出现1个激增点,此时土体模量呈“急剧—平稳—急剧”的衰减规律,并且频率越低或循环应力比越大,应变发展及模量衰减速度越快,达到结构崩塌所需要的循环次数越少。频率和循环应力比对原状软黏土的孔压与损耗能关系及崩塌能均有影响,且频率越低或循环应力比越大,孔压随损耗能发展越快,结构崩塌时的崩塌能也越小。频率和循环应力比是通过改变损耗能中两部分能量所占的比例来实现对孔压与损耗能关系及崩塌能的影响。

 

关键字: 主应力轴旋转;原状软黏土;频率;循环应力比;损耗能量;孔压;崩塌能

Dynamic characteristics of isotropically consolidated intact soft clay and study of pore water pressure based on energy method under wave loading
YANG Yanhao1, 2, ZHOU Jian1, 2, WEN Xiaogui1, 2, YAN Jiajia1, 2, CAO Yang1, 2

1. Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China
2. Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China

Abstract:A series of tests with principal stress rotation were carried out on 5 Hz ZJU-HCA to investigate the dynamic characteristics of isotropically consolidated Hangzhou intact soft clay under wave loading. The dynamic characteristics such as the development of strain and degradation of modulus were studied under different frequencies or cyclic stress ratios. Furthermore, the relationship between pore water pressure and the dissipated energy as well as the collapse energy were analyzed based on energy method. The result show that under principal stress rotation, there exists a threshold cyclic stress ratio in the intact soft clay. When the cyclic stress ratio is smaller than the threshold value, the strains only develop in a small range and the modulus of the soft clay attenuates in a sharp-steady mode; when it is larger than the threshed value, there is an abrupt point in the strain verse cyclic number line due to the structural collapse of soil. Meanwhile the modulus decreases in a sharp-steady-sharp way, and the lower the frequency or the larger the cyclic stress ratio is, the faster the strains develop and the modulus degenerates, the fewer cyclic numbers required to achieve the structural collapse. Frequency and cyclic stress ratio have some influence on the relationship between pore water pressure and dissipated energy as well as the collapse energy, that is, the lower the frequency or the larger the cyclic stress ratio, the faster the pore water pressure develops with dissipated energy, and the less the collapse energy. The frequency and cyclic stress ratio affect the relationship between pore water pressure and dissipation energy as well as the collapse energy through changing the percentage of the two parts energy.

 

Key words: principal stress rotation; intact clay; frequency; cyclic stress ratio; dissipated energy; pore water pressure; collapse energy

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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