| 卢氏膨胀岩在干湿循环作用下的胀缩特性研究 |
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| 引用本文： | 张善凯,冷先伦,盛谦,李彪,周永强.卢氏膨胀岩在干湿循环作用下的胀缩特性研究[J].岩土力学,2019,40(11):4279-4288. |
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| 作者姓名： | 张善凯 冷先伦 盛谦 李彪 周永强 |
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| 作者单位： | 1. 中国科学院武汉岩土力学研究所 湖北省环境岩土工程重点实验室，湖北 武汉 430071；
2. 中国科学院大学，北京 100049；3. 山东大学 土建与水利学院，山东 济南 250061 |
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| 基金项目： | 国家重点研发计划项目（No.2018YFC0809400，No.2017YFF0108705，No.2017YFF0108706）；国家自然科学基金资助项目（No.11472292，No.51679232）；陕西省交通运输厅2016年度交通科研项目（16-18K）。 |
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| 摘 要： | 为研究卢氏膨胀岩的胀缩特性，开展了干湿循环作用下膨胀岩的胀缩特性试验研究，并在膨胀岩经历干湿循环后利用扫描电子显微镜（SEM）和氮吸附试验（NA），从微观的角度分析了膨胀岩吸水膨胀失水收缩的现象，并解释了胀缩特性改变的原因。研究结果表明：卢氏膨胀岩膨胀率随干湿循环次数增加而增大，绝对膨胀率增加25%；收缩曲线出现明显的“收缩拐点”，一般在收缩总时间的20%时出现，这时膨胀岩失水状态由自由水的散失转变为结合水的散失；在膨胀岩第1次胀缩过程中出现裂缝，裂缝为贯通状；在之后的胀缩过程中出现的裂缝较浅且随干湿循环次数的增加裂缝发育逐渐稳定；在干湿循环次数达到6～8次后，卢氏膨胀岩胀缩率达到稳定值，绝对膨胀率稳定在17%，绝对收缩率稳定在9%；微观方面随干湿循环次数的增加，膨胀岩的微观结构中黏土颗粒聚集形态由紧密状态转变为松散状态。此外，试样的孔隙特征随干湿循环次数的增加表现出孔隙总体积逐渐增大、孔径逐渐减小、比表面积逐渐增大的规律。
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| 关 键 词： | 膨胀岩 干湿循环 胀缩特性 微观结构 孔隙分布 |
| 收稿时间： | 2018-09-19 |
Swelling and shrinkage characteristics study of Lushi expansive rock under dry and wet circulation |
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| ZHANG Shan-kai,LENG Xian-lun,SHENG Qian,LI Biao,ZHOU Yong-qiang.Swelling and shrinkage characteristics study of Lushi expansive rock under dry and wet circulation[J].Rock and Soil Mechanics,2019,40(11):4279-4288. |
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| Authors: | ZHANG Shan-kai LENG Xian-lun SHENG Qian LI Biao ZHOU Yong-qiang |
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| Institution: | 1. Hubei Key Laboratory of Geo-Environmental Engineering, Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences, Wuhan, Hubei 430071, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. School of Civil Engineering, Shandong University, Jinan, Shandong 250061, China |
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| Abstract: | To investigate the expansion and shrinkage characteristics of the Lushi expansion rock, experimental study on the expansive rock expansion and contraction characteristics under dry-wet cycle was carried out. After experiencing dry and wet cycles, the expansive rock was analyzed by scanning electron microscopy (SEM) and nitrogen adsorption experiment (NA). The phenomenon of swelling and water shrinkage of expansive rock was analyzed from the microscopic point of view, and the reason for the change of expansion and contraction characteristics was explained. The results show that the expansion rate of expansive rock increases with the increase of dry and wet circulation, and the absolute expansion rate increases by 25%. The contraction curve shows an evident contraction inflection point, which usually occurs at 20% of the total shrinkage time. At this time, the water loss state of the expansion rock changes from the free water loss to the combined water loss. Cracks appear during the first expansion and contraction of the expansive rock, which are transfixion. In the later expansion and contraction process, the cracks appeared shallower gradually stabilized with the increase of dry and wet circulation. After the number of cycles reached 6-8, the expansion and shrinkage rate of Lushi expansion rock reached a stable value, with the absolute expansion rate stable at 17% and the absolute contraction rate stable at 9%. As the number of dry and wet cycles increased, the aggregation of clay particles in the microstructure of expansive rock changed from compact state to loosen. In addition, the pore characteristics of the sample show that total pore volume gradually increases, the pore diameter gradually decreases, and the specific surface area gradually increases with the increase of the number of dry and wet cycles. |
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| Keywords: | swelling rock wetting-drying cycle swell-shrink characteristic microstructure pore distribution |
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