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| 基于SEM分析的湖相软土固结变形特性研究 |
| Study on consolidation deformation characteristics of lacustrine soft soil based on SEM analysis |
| 投稿时间：2018-12-07 修订日期：2019-01-18 |
| DOI： |
| 中文关键词: 软土 固结 GDS 微观结构 分形理论 |
| 英文关键词: Soft soil Consolidation GDS Microstructure Fractal theory |
| 基金项目:江西省水工程安全与资源高效利用工程研究中心开放基金项目（OF201603）；江西省科技重点研发计划项目(20077BBG70046)；国家自然科学基金应急管理项目(4164102）,南昌工程学院第十六届挑战杯项目。 |
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| 中文摘要: |
| 鄱阳湖区软土具有河湖交互沉积的湖相软土“千层饼”特征，其固结特性与土体颗粒结构密切相关，采用扫描电子显微镜（SEM）和PCAS软件可以定量研究固结过程中微观结构的动态变化，分析两者之间的相关性。通过不同固结压力的GDS固结不排水试验，开展固结试样的SEM扫描和定量分析。结果表明：在低固结压力时，湖相软土主固结和次固结分界点不明显，随着固结压力的增加，湖相软土的主固结比增大，次固结占比减少；当固结压力较小时，湖相软土的微观结构主要呈絮状等不规则形状，当固结压力增大到400kPa以后，软土颗粒结构变为蜂窝状等均一性比较高的结构，土体的可压缩性减小。随着固结压力的增大，孔隙由不定向排列向定向化排列转变。当固结压力≤400kPa时，随着固结压力的增大，孔隙度分维值降雨曲线斜率较大，降低速率较快，概率熵在0.96以上；当固结压力＞400kPa时，随着固结压力的增大，孔隙度分维值变化曲线斜率放缓，降低速率减慢，概率熵快速降低；固结压力越大，平均形状系数越高，分形维数越低，在固结压力≤400kPa时，平均形状系数增加较快，而分形维数降速较快；当固结压力＞400kPa时，随着固结压力的增大，平均形状系数和分形维数基本不变；固结压力与孔隙度分维值、概率熵、平均形状系数和分形维数的相关系数均大于0.81，具高度相关性。 |
| 英文摘要: |
| The soft soil in Poyang lake area has the characteristics of "thousand-layer cake" of lacustrine soft soil deposited by river and lake interactions, and its consolidation characteristics are closely related to the soil particle structure. The quantitatively study of the dynamic changes of microstructure during the consolidation process was analyzed by scanning electron microscope (SEM) and PCAS software. SEM scanning and quantitative analysis of consolidation samples were carried out through GDS consolidation undrained tests with different consolidation pressures. The results show that the boundary points of primary consolidation and secondary consolidation of lacustrine soft soil are not obvious at low consolidation pressure. When the consolidation pressure is small, the microstructure of lacustrine soft soil is mainly flocculent and other irregular shapes. When the consolidation pressure increases to 400kPa, the granular structure of soft soil becomes honeycomb and other structures with high uniformity, and the compressibility of soil decreases. With the increase of consolidation pressure, the pores change from non-directional arrangement to directional arrangement. When the consolidation pressure is less than 400kPa, as the consolidation pressure increases, the slope of the fractal dimension of porosity rainfall curve is larger and the reduction rate is faster, and the probability entropy is above 0.96. When the consolidation pressure is > 400kPa, with the increase of the consolidation pressure, the slope of the fractal dimension value change curve of porosity slows down, the rate of decrease slows down, and the probability entropy decreases rapidly. The higher the consolidation pressure is, the higher the average shape coefficient is, and the lower the fractal dimension is. When the consolidation pressure is less than or equal to 400kPa, the average shape coefficient increases faster, while the fractal dimension decreases faster. When the consolidation pressure is > 400kPa, the average shape coefficient and fractal dimension are basically unchanged with the increase of the consolidation pressure. The correlation coefficients between consolidation pressure and fractal dimension value of porosity, probability entropy, average shape coefficient and fractal dimension are all greater than 0.81, showing a high correlation. |
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