基质吸力对非饱和粉质砂土抗剪强度的影响
来源期刊：中南大学学报(自然科学版)2012年第10期
论文作者：董倩 侯龙 赵宝云
文章页码：4017 - 4021
关键词：非饱和土；水-土特征曲线；基质吸力；抗剪强度；水-气交界面
Key words：unsaturated soil; soil-water characteristic curve; matric suction effect; shear strength; gas-liquid interface
摘 要：从宏观吸力控制型直剪试验和微观土体颗粒结构分析两方面入手，在压力板仪试验分析非饱和粉质砂土 水-土特性的基础上，采用不同吸力条件下的直剪试验和2种不同含水量土样结构的微观扫描研究，分析非饱和粉质砂土抗剪强度和基质吸力之间的关系。研究结果表明：与黏性土不同，当粉质砂土含水量逐渐降低时，土体基质吸力对土体抗剪强度的贡献效果并不是一直增加，而是存在一个“峰值效应”，这种现象的出现是由于粉质砂土微观结构的组成特点以及随含水率减小所含水分的存在形式不断改变这两方面因素，致使基质吸力作用面积不断变化造成的。另外，土体的应力环境也会影响吸力对土体强度贡献的大小。
Abstract: Based on the analysis of the soil-water characteristic of unsaturated silty sand through pressure plate instrument test, the suction control direct shear tests under different suction conditions of unsaturated silty sand were studied. And then, the microscopic structures of two kinds of soil samples with different water contents were scanned to analyze the relationship between the matric suction and the shear strength of unsaturated silty sand. The results show that unsaturated silty sand is different from unsaturated clayey soil. When water content gradually reduces, the soil shear strength of unsaturated silty sand is not always increased with the increase of matric suction, but there is a “peak effect”. The appearance of “peak effect” is due to the fact that unsaturated silty sand has its own microstructure characteristics, and that with the decrease of the moisture content, the existence form of moisture changes gradually. The two factors cause the effect area of matric suction to change constantly, and then influence shear strength of unsaturated silty sand to appear “peak effect”. In addition, the stress environment also can influence contribution degree of matric suction to the shear strength of unsaturated silty sand.
董倩1,2，侯龙2,3，赵宝云1,2
(1. 重庆科技学院 建筑工程学院，重庆，401331；
2. 重庆大学 土木工程学院，重庆，400045；
3. 美国科罗拉多矿业大学 土木与环境工程学部，美国 戈尔登，80401)
摘 要：从宏观吸力控制型直剪试验和微观土体颗粒结构分析两方面入手，在压力板仪试验分析非饱和粉质砂土 水-土特性的基础上，采用不同吸力条件下的直剪试验和2种不同含水量土样结构的微观扫描研究，分析非饱和粉质砂土抗剪强度和基质吸力之间的关系。研究结果表明：与黏性土不同，当粉质砂土含水量逐渐降低时，土体基质吸力对土体抗剪强度的贡献效果并不是一直增加，而是存在一个“峰值效应”，这种现象的出现是由于粉质砂土微观结构的组成特点以及随含水率减小所含水分的存在形式不断改变这两方面因素，致使基质吸力作用面积不断变化造成的。另外，土体的应力环境也会影响吸力对土体强度贡献的大小。
关键词：非饱和土；水-土特征曲线；基质吸力；抗剪强度；水-气交界面
DONG Qian1,2, HOU Long2,3, ZHAO Bao-yun1,2
(1. Department of Civil Engineering and Architecture,
Chongqing University of Science and Technology, Chongqing 401331, China;
2. Department of Civil Engineering, Chongqing University, Chongqing 400045, China;
3. Faculty of Civil and Environmental Engineering, Colorado School of Mines, Golden 80401, USA)
Abstract:Based on the analysis of the soil-water characteristic of unsaturated silty sand through pressure plate instrument test, the suction control direct shear tests under different suction conditions of unsaturated silty sand were studied. And then, the microscopic structures of two kinds of soil samples with different water contents were scanned to analyze the relationship between the matric suction and the shear strength of unsaturated silty sand. The results show that unsaturated silty sand is different from unsaturated clayey soil. When water content gradually reduces, the soil shear strength of unsaturated silty sand is not always increased with the increase of matric suction, but there is a “peak effect”. The appearance of “peak effect” is due to the fact that unsaturated silty sand has its own microstructure characteristics, and that with the decrease of the moisture content, the existence form of moisture changes gradually. The two factors cause the effect area of matric suction to change constantly, and then influence shear strength of unsaturated silty sand to appear “peak effect”. In addition, the stress environment also can influence contribution degree of matric suction to the shear strength of unsaturated silty sand.
Key words:unsaturated soil; soil-water characteristic curve; matric suction effect; shear strength; gas-liquid interface
