人工制备黄土湿陷性影响因素及微观机理研究

基于模型试验相似理论和Monte Carlo原理,选用石英粉、砂、膨润土、石膏和工业盐,采用空中试验自由下落法制备人工湿陷性黄土。对不同含水量和压实度的土样进行土工试验、能谱仪元素分析和电镜扫描测试。试验结果表明:该人工黄土的元素组成与天然湿陷性黄土具有一致性;人工制备黄土的湿陷性随着初始含水量的增加呈先增大后减小的趋势,随着压实度的增大线性减小,湿陷规律与天然湿陷性黄土相似;该人工黄土具有易受应力状态和浸水影响的结构性。随着压实度和含水量的增大,颗粒的各向异性、面积比和等效直径增大,而扁圆度和充填比减小。土的湿陷系数与各向异性、扁圆度、面积比等微结构参数存在着良好的相关关系。从微观角度合理地解释了该人工黄土相似材料的湿陷性机理,与天然黄土湿陷规律有较高的契合度。

Research on the Collapsibility Influencing Factors and Micro-mechanism of Artificial loess

Based on the similarity theory of model test and the principle of Monte Carlo,quartz powder,sand,bentonite,gypsum and industrial salt were chosen to prepare artificial collapsible loess with air fall method.Soil samples with different water contents and compaction degrees were taken to conduct geotechnical test,EDS test and electron microscope scanning test.Test results prove that the artificial loess has a high coherence with nature collapsible loess in the view of elemental composition;with the increase of initial moisture content,collapsibility coefficient increases first and then decreases,and collapsibility coefficient decreases linearly with the increase of compaction degree,which shows that collapsible behavior is similar with that of nature collapsible loess;The artificial loess has the structure which is sensitive to be influenced by the stress state and water immersion.with the increase of compaction degree and moisture content,particle anisotropy,area ratio and equivalent diameter increase,while particle oblate degree and fill ratio decrease.There is a good relationship between coefficient of collapsibility and microstructure parameters such as anisotropy,oblate degree and area ratio.Frown the microscopic point of view,collapsible mechanics of the artificial collapsible loess is elaborated reasonably,which has compatible degree with the collapsible law of natural loess.