| 循环应力比和振动频率对盐渍土微观结构影响分析 |
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| 引用本文： | 赵福堂,常立君,张吾渝.循环应力比和振动频率对盐渍土微观结构影响分析[J].冰川冻土,2020,42(3):854-864. |
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| 作者姓名： | 赵福堂 常立君 张吾渝 |
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| 作者单位： | 青海大学 土木工程学院，青海 西宁 810016 |
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| 基金项目： | 青海省科技厅项目(2017-ZJ-791);国家自然科学基金项目(51768060);青海省创新服务平台建设专项(2018-ZJ-T01) |
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| 摘 要： | 以青海省察尔汗地区盐渍土为研究对象， 借助扫描电子显微镜（SEM）设备和颗粒孔隙及裂隙图像识别与分析系统（PCAS）， 应用图像分割原理和分形理论， 对交通循环荷载作用下的盐渍土微观结构进行研究， 探讨不同循环应力比和不同振动频率下孔隙分布特征及其微观机制。结果表明： 循环应力比R由0.375增加到0.75， 临界破坏动应变由2.32%增高到3.17%， 动载循环次数相应减少； 振动频率f由0.5 Hz增加到2.0 Hz， 临界破坏动应变由2.82%减小到2.48%， 动载循环次数相应增多； 盐渍土孔隙参数随循环应力比的增大， 孔隙尺度分维值Dv 增长了0.12， 概率熵Hm 减小了0.017， 孔隙的形态分形维数D减小了0.27， 平均形状系数F增加了0.14， 变化规律较明显； 随振动频率的增大， Dv 增长了0.014， Hm 减小了0.002， D变化了0.06， F变化了0.003， 变化规律不明显； 在动荷载作用下， 试样的孔隙空间排列与宏观上的褶皱鼓状变形具有一致性。通过未加载试样与加载后试样的微观结构参数变化对比， 从循环应力比和振动频率对盐渍土微观孔隙特征的影响到宏观变形的相互作用机制进行了系统分析。
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| 关 键 词： | 盐渍土 微观孔隙 电镜扫描 动三轴试验 循环应力 振动频率 |
| 收稿时间： | 2019-04-14 |
| 修稿时间： | 2020-01-13 |
Analysis on the influence of cyclic stress ratio and vibration frequency on microstructure of saline soil |
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| Futang ZHAO,Lijun CHANG,Wuyu ZHANG.Analysis on the influence of cyclic stress ratio and vibration frequency on microstructure of saline soil[J].Journal of Glaciology and Geocryology,2020,42(3):854-864. |
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| Authors: | Futang ZHAO Lijun CHANG Wuyu ZHANG |
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| Institution: | School of Civil Engineering，Qinghai University，Xining 810016，China |
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| Abstract: | Taking saline soil in the Qarhan area as the research object， using Scanning Electron Microscope （SEM） equipment and particle pore and crack image recognition and analysis system （PCAS）， microscopic quantitative identification and structural analysis are carried out. Applying image segmentation principle and fractal theory to study the microstructure of saline soil under traffic cyclic loading， the characteristics of pore distribution and its microscopic mechanism under different cyclic stress ratios and different frequencies are discussed. The results show that the cyclic stress ratio R increases from 0.375 to 0.75， the critical failure dynamic strain increases from 2.32% to 3.17%， and the number of dynamic load cycles decreases accordingly. The vibration frequency f increases from 0.5 Hz to 2.0 Hz， the critical failure dynamic strain reduces from 2.82% to 2.48%， and the number of dynamic load cycles increases correspondingly. The microscopic parameters of saline soil increase with the cyclic stress ratio， fractal dimension value of pore scale Dv increases by 0.12， probability entropy Hm decreases by 0.017， fractal of the morphology of pores D decreases by 0.27， average shape coefficient F increases by 0.14； the microscopic parameters increase with the vibration frequency， Dv increases by 0.014， Hm decreases by 0.002， D changes by 0.06， average shape coefficient F changes by 0.003. Under dynamic loading， the pore space arrangement of sample is consistent with the fold and drum deformation of the macroscopic soil. Based on the comparison of microstructure parameters about the unloaded sample and loaded sample， the interaction mechanism between cyclic stress ratio and vibration frequency on the saline soil microscopic pore characteristics and macroscopic deformation has systematically analyzed. |
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| Keywords: | saline soil micro-pore structure Scanning Electron Microscope （SEM） dynamic tri-axial test cyclic stress vibration frequency |
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