摘要
堆积体边坡动力响应特性复杂,影响因素众多。已有的大型动三轴试验结果表明,含水状态对堆积体的动剪切模量比与阻尼比有重要影响。针对含水状态这一因素,开展了2组不同含水率的1:12比尺的大型振动台堆积体边坡模型试验,对比分析了其在连续地震荷载序列作用下的加速度响应特性与坡顶位移发展趋势。试验结果表明:2组边坡模型均表现出第一阶自振频率随着加载序列递减、阻尼比随着加载序列增大的现象,但含水率为6.6%时,边坡第1阶自振频率与阻尼比均大于含水率为0.7%的堆积体边坡。堆积体边坡含水率为6.6%时的输入地震动峰值加速度(PGA)放大系数大于堆积体边坡含水率为0.7%时的工况。2组模型坡顶水平响应加速度的傅里叶频谱特征相似,均表现出输入地震波的特征频率越接近模型第1阶自振频率,坡顶水平加速度放大效应越明显,而且从低频侧接近第1阶自振频率的响应比从高频侧接近的要显著。含水率为6.6%的堆积体边坡在多级地震荷载作用下的坡顶永久位移均大于含水率为0.7%的边坡,堆积体边坡含水率为6.6%,坡顶永久位移对输入地震波的频谱特性更敏感。研究结论有助于增强不同含水状态对堆积体边坡动力响应规律影响的认识。
Dynamic response of deposit slopes is complex with multiple influencing factors. The large-scale dynamic triaxial tests reveal that moisture content affects greatly on dynamic shear modulus and damping ratio of deposit. As such, two groups of large-scale shaking table model with scale of 1：12 of deposit slopes are tested with different moisture contents. Comparisons of acceleration and crest displacements distribution of 2 deposit slopes under multiple sequential ground motions show that, in either 2 models with different moisture conditions, the first order natural frequencies of model slopes decrease with the increasing loading sequence, while the corresponding damping ratios increase with its increasing. The slope model with 6.6% moisture content has larger numbers of first order natural frequency, damping ratio and peak ground acceleration（PGA） amplification coefficients than the numbers for model with 0.7% moisture content. The Fourier spectrum of slope crest accelerations of these 2 models are similar. The amplification effect of crest acceleration enhances evidently when the predominant frequencies of input seismic waves approach to the first order natural frequencies of the deposit slope. the input frequencies of seismic waves approaching the first order natural frequency from the lower frequencies side of slope amplifies PGA significantly than from the higher frequencies side. The permanent displacements of deposit slope crest with 6.6% moisture content are larger than that of 0.7% moisture content slope. In addition, the crest permanent displacements with higher moisture content are more sensitive to the spectra characteristics of input seismic waves.
作者
孙志亮
孔令伟
郭爱国
SUN Zhi-liang;KONG Ling-wei;GUO Ai-guo(State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第7期2433-2441,2460,共10页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.41372314
No.41702348)~~
关键词
堆积体边坡
含水状态
振动台模型试验
加速度响应
永久位移
deposit slope
moisture condition
shaking table model test
acceleration response
permanent displacement
