| 动渗耦合作用下软黏土渗透系数演化机制分析 |
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| 引用本文： | 雷华阳,许英刚,蒋明镜,刘旭,缪姜燕.动渗耦合作用下软黏土渗透系数演化机制分析[J].岩土力学,2022,43(10):2665-2674. |
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| 作者姓名： | 雷华阳 许英刚 蒋明镜 刘旭 缪姜燕 |
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| 作者单位： | 1. 天津大学 土木工程系，天津 300350；2. 天津大学 天津市土木工程结构及新材料重点实验室，天津 300350；
3. 天津大学 中国地震局地震工程综合模拟与城乡抗震韧性重点实验室，天津 300350 |
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| 基金项目： | 国家自然科学基金（No. 52078334）；国家自然科学基金重大项目（No. 51890911）。 |
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| 摘 要： | 针对天津地区滨海软黏土，开展了一系列动渗耦合三轴试验，系统分析了长期循环作用下软黏土渗透系数的变化规律。结合扫描电镜（SEM）和压汞试验（MIP）对不同变形阶段软黏土的微观结构特征进行分析，阐述了渗透系数的演化规律及机制。研究表明：在动渗耦合作用下，软黏土渗透系数呈现三阶段变化特征；渗透系数随渗流力呈现先增大后减小的变化规律，随动应力和频率呈现先减小后增大的特征。微观试验表明，渗透系数的演化是微结构孔隙大小、形态、分布特征渐进调整的宏观体现：加载初期，颗粒间的架空超大孔隙（孔隙直径D>2.5 μm）大幅压缩，孔隙形态变化不大，渗透系数呈线性衰减；加载中期，大颗粒破碎生成的小颗粒密布填充于大颗粒间，生成大量“密小而曲折”的小孔隙（0.05 μm<D<0.1 μm），渗透系数呈现缓慢下降；加载末期，结构致密稳定，渗透系数基本不变。对于非稳定变形，颗粒团（聚）体间重新生成“条带”状孔隙，渗透系数反弹增大。该研究成果可为流固耦合分析中渗透系数的确定提供理论依据。
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| 关 键 词： | 软黏土 动渗耦合 渗透系数 扫描电镜（SEM） 压汞试验（MIP） 演化机制 |
| 收稿时间： | 2021-12-15 |
| 修稿时间： | 2022-06-21 |
Evolution mechanism of permeability of soft clay under coupled
cyclic-seepage loads |
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| LEI Hua-yang,XU Ying-gang,JIANG Ming-jing,LIU Xu,MIAO Jiang-yan.Evolution mechanism of permeability of soft clay under coupled
cyclic-seepage loads[J].Rock and Soil Mechanics,2022,43(10):2665-2674. |
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| Authors: | LEI Hua-yang XU Ying-gang JIANG Ming-jing LIU Xu MIAO Jiang-yan |
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| Institution: | 1. Department of Civil Engineering, Tianjin University, Tianjin 300350, China;
2. Tianjin Key Laboratory of Civil Engineering Structures and New Materials, Tianjin University, Tianjin 300350, China;
3. Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience, China Earthquake Administration, Tianjin University, Tianjin 300350, China |
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| Abstract: | A series of triaxial tests was carried out
under coupled cyclic-seepage loads for Tianjin coastal soft clay, and the
variation of permeability in different loading stages was analyzed
systematically. Combined with SEM and MIP, the evolution mechanism of
permeability was elaborated. The results showed that under the coupling
cyclic-seepage loads, the permeability of soft clay present three variation
stages. With seepage loads increasing, the permeability increased initially and
then decreased, but just reverse for increase of critical dynamic stress ratio.
The evolution of permeability was caused by the adjustment of micro-features of
pore shape, size, and distribution: for initial vibration, large compression of
super large pores (D>2.5 μm) between particles occurred and pore shape varied
little, leading to the linear reduction of permeability; at the medium loading
stage, the large particles were broken, and the newly formed small particles
were densely filled between the large particles, inducing a large number of “compact
and zigzag” small pores (0.05 μm <D<0.1
μm),
which led to the slow decrease of permeability; at later loading stage, the
structure was compact and stable, and permeability was basically unchanged. For
the unstable deformation, the “strips” like macropores were re-formed between
the particle clusters (aggregates), and the permeability increased. The results
can provide a theoretical basis for the determination of the permeability in
the fluid-solid coupling analysis. |
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| Keywords: | soft clay cyclic-seepage coupling permeability scanning electron microscope (SEM) mercury intrusion porosimetry (MIP) evolution mechanism |
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