| 饱和软土三轴剪切特性与微观结构关系试验 |
| |
| 引用本文： | 刘勇健,杨鑫,罗岚,李彰明,梁仕华,方昊圆.饱和软土三轴剪切特性与微观结构关系试验[J].中国公路学报,2019,32(7):15-22. |
| |
| 作者姓名： | 刘勇健 杨鑫 罗岚 李彰明 梁仕华 方昊圆 |
| |
| 作者单位： | 广东工业大学 岩土工程研究所, 广东 广州 510006 |
| |
| 基金项目： | 国家自然科学基金项目（51178122）；广东省自然科学基金项目（2016A030313692）；广州市科技计划项目（201607010319） |
| |
| 摘 要： | 天然土体均具有一定的物质组成和内部结构，因而表现出不同的工程特性。为探求软土在剪切变形过程中微观结构的演化规律，研究土体的宏观物理力学性质与微观结构之间的相互关系，对珠江三角洲饱和软土进行真三轴剪切试验和核磁共振试验，获取不同剪切速率条件下不同应变阶段的软土力学响应特征和孔隙微观结构参数。试验结果表明：三轴试验前后软土的孔径均主要集中在1～20 μm区间，经三轴剪切试验后软土的微观结构及其参数均发生了不同程度的变化，如平均孔隙半径减小，孔隙率降低，含水率减少。在剪切过程中，软土的剪切变形存在一个应变阈值（竖向应变4%～5%），当竖向应变小于应变阈值时，软土的小孔隙的百分数随应变增大而减小，中、大孔隙百分数随应变增加而增加；当竖向应变大于阈值后，孔隙分布随应变的变化趋势则反之。软土的微观结构形态及其微观结构参数变化受剪切速率和土的应变值这2个因素影响较明显；孔隙形状参数（S/V）随土的应力状态（广义剪应力q和应变εs）有规律变化。此外，从微观结构层次和分子动力学角度揭示了软土剪切力学行为，软土剪切过程实质是土微（细）观结构不断自我调整的过程，土体的受力变形在微观上主要表现为孔隙大小和形状的变化。
|
| 关 键 词： | 道路工程 饱和软土 核磁共振试验 剪切特性 微观结构 |
| 收稿时间： | 2018-06-06 |
Experimental Research on Relationship Between Triaxial Shear Properties and Microstructure of Saturated Soft Soil |
| |
| LIU Yong-jian,YANG Xin,LUO Lan,LI Zhang-ming,LIANG Shi-hua,FANG Hao-yuan.Experimental Research on Relationship Between Triaxial Shear Properties and Microstructure of Saturated Soft Soil[J].China Journal of Highway and Transport,2019,32(7):15-22. |
| |
| Authors: | LIU Yong-jian YANG Xin LUO Lan LI Zhang-ming LIANG Shi-hua FANG Hao-yuan |
| |
| Affiliation: | Institute of Geotechnical Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China |
| |
| Abstract: | Natural soils have their material composition and internal structure; thus,they have different engineering properties. In order to reveal the evolution of soil microstructure in the deformation process, analyze the relationship between macro characteristics and microstructure of soft soil. Using the true triaxial shear test and nuclear magnetic resonance test, the mechanical response and microstructure characteristics of saturated soft soil in the Pearl River Delta were obtained at different shear rates and different strain stages. The results show that the pore size of soft soil is mainly concentrated in the range of 1 μm to 20 μm before and after the triaxial experiment, The microstructure was adjusted to different degrees after the triaxial shear test, such as the decrease in the average pore radius, porosity, and water content. A vertical strain threshold existed (approximately 4%-5%) during the shear process, that means, when the vertical strain is less than the threshold of strain, the distribution of small pores decreases with the increasing of strain and percentage of the medium pores and large pores increase with the increasing of strain. When the vertical strain is larger than the threshold, the opposite trend is true.The microstructural shape and parameters of soft soil were affected by two factors:shear rate and soil strain. The pore shape parameter (S/V) varied with the generalized shear stress q and generalized shear strain εs, which indicates the intrinsic correlation between microstructure and stress (strain).The results also show that the internal mechanism of the shear mechanical behavior of soft soil from the view of microstructure and molecular dynamics, and the deformation of soil is mainly reflected in the variations of pore size and shape at the micro level. |
| |
| Keywords: | road engineering saturated soft soil nuclear magnetic resonance test shear characteristics microstructure |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《中国公路学报》浏览原始摘要信息 |
|
点击此处可从《中国公路学报》下载全文 |
|
