| 基于Menger海绵模型的煤矸石粉改良膨胀土微结构特征 |
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| 引用本文： | 王明磊,张雁,殷潇潇.基于Menger海绵模型的煤矸石粉改良膨胀土微结构特征[J].农业工程学报,2020,36(23):124-130. |
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| 作者姓名： | 王明磊 张雁 殷潇潇 |
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| 作者单位： | 内蒙古农业大学能源与交通工程学院,呼和浩特 010018;内蒙古农业大学能源与交通工程学院,呼和浩特 010018;城发投资集团有限公司,青岛 266555 |
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| 基金项目： | 国家自然科学基金项目（51669025） |
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| 摘 要： | 为解决膨胀土对工程结构以及农业生态环境的危害,进行煤矸石粉改良膨胀土的试验研究。对煤矸石粉掺量为0、3%、6%、9%的膨胀土土样进行压汞试验,测得微观孔隙特征值;选取Menger海绵模型建立孔隙分分形模型,计算土体孔隙分形维数,探究土体孔隙分形维数与孔隙特征参数以及煤矸石粉掺量变化的关系。结果表明：随着煤矸石粉掺量增加,土中大孔隙所占的含量较素膨胀减少61.5%,孔隙类型从团粒间孔隙转化为颗粒间孔隙;煤矸石粉的掺入改变了土体的孔隙结构特征,煤矸石粉与膨胀土发生胶结反应,孔隙连通性降低,使得总孔隙体积、孔隙率、孔隙平均孔径、孔隙临界孔径等孔隙特征参数呈减小趋势;基于分形理论分析孔隙分形维数,分形维数随煤矸石粉掺量的增加而增加,且与孔隙特征参数呈显著相关性。孔隙分形维数反应了孔隙特征参数以及孔隙发育程度,为土的孔隙表征提供方法借鉴。
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| 关 键 词： | 膨胀土 孔隙度 煤矸石 Menger海绵模型 分形 压汞法 |
| 收稿时间： | 2020/9/25 0:00:00 |
| 修稿时间： | 2020/11/17 0:00:00 |
Microstructure characteristics of expansive soil with coal gangue based on Menger sponge model |
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| Wang Minglei,Zhang Yan,Yin Xiaoxiao.Microstructure characteristics of expansive soil with coal gangue based on Menger sponge model[J].Transactions of the Chinese Society of Agricultural Engineering,2020,36(23):124-130. |
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| Authors: | Wang Minglei Zhang Yan Yin Xiaoxiao |
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| Institution: | 1. College of Energy and Transportation Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China;; 1. College of Energy and Transportation Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; 2. Chengfa Investment Group, Qingdao 266555, China |
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| Abstract: | Expansive soil is a type of highly plastic clay, where the volumetric expansion upon water absorption (hygroscopic expansion), while the shrinkage upon water loss. This property can be detrimental to the soil structure, resulting in a series of civil engineering problems, such as soil surface cracking, subgrade settlement, and road surface uplift. Alternatively, coal gangue is a kind of rock waste discharged from coal mining, washing, and processing during coal production. Serious influences have occurred in the social, environmental, and economic respects. An eco-friendly way to save energy is to effectively reuse the coal gangue as a substitute resource. This study aims to improve the properties of expansive soil using the coal gangue, in order to alleviate the damage of expansive soil in engineering, thereby to explore the porosity characters of improved expansive soil with coal gangue. A Menger sponge model was selected to characterize the fractal dimension of pores, in order to guide the development of curing agent, and thereby control the pore structure of expansive soil via the fractal characteristics. A mercury injection test was performed on the samples of expansive soil with the content of coal gangue of 0, 3%, 6% and 9%, respectively. Prior to the mercury injection test, compaction specimens were fabricated from the state of extraction saturation to vacuum saturation state. The gas pressure of pores was approximate to zero in the sample of improved expansive soil for the dilatometer in mercury injection apparatus. A low-pressure mercury injection was first used to analyze the soil samples. The dilatometer was then taken out to weigh the mass on a high precision balance. A mercury pressure analysis was carried out on the soil samples until the pressure gradually decreased to atmospheric pressure. The results show that the mercury injection can be divided into the process of mercury injection and removal. When the pressure was small, there was the large equivalent diameter of pores corresponding to the pressure, where mercury can only enter the large pores in the soil sample, resulting the small cumulative amount of mercury injection. The pore diameter gradually decreased as the pressure increased, where mercury can enter the smaller pores in the soil, and thereby the accumulated amount of mercury gradually increased. With the increase in the content of coal gangue powder, the accumulative content of mercury in the improved soil significantly decreased, where the most obvious content were 6% and 9%. Large micropores decreased by 61.5% in the expansion content of macropores. There was a trend of decrease in the total volume of pores, the critical aperture porosity, average pore diameter, and pore porosity index. Pore types were transformed from the pores between the aggregates to the pores between particles, indicating an obviously enhanced effect in the addition of coal gangue to the expansive soil. In order to study the relationship between the pore fractal dimension and pore characteristics, a Menger sponge model was used to characterize the fractal dimension of pores in the improved soil, where the values varied from 2.59-2.87. A dependent law was obtained between the fractal dimension of pores and the characteristic parameters of pores in multiple linear regressions. In "F" and "t" test of regression model, it was found that the porosity and critical pore size had a significant influence on the fractal dimension of pores. The fractal dimension of pores increased in the improved expansive soil with the increase in powder content of coal gangue. The large fractal dimension indicated that there was an orderly arrangement of pores and shape characteristics in the improved soil. The fractal dimension of pores can be used to visually represent the measurement data of pore structure, further to verify the pore characteristic parameters, and pore development degree, serving as an indirect indicator of the heterogeneity and complexity of soil. |
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| Keywords: | expansive soils porosity coal gangue MENGER sponge model fractal mercury intrusion |
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