摘要:
为研究黄土的崩解特性，探讨黄土崩解机理，以黑方台马兰黄土为研究对象，通过自制的黄土崩解装置，对该地区原状黄土进行了一系列的室内崩解试验。选择影响黄土崩解的土样尺寸、初始含水率、水温、酸碱度、盐度5种因素，采用控制变量法逐一进行崩解测试，记录崩解的整个过程，绘制崩解曲线，求出对应的崩解速率，进行拟合，得到崩解速率与各变量间的关系。试验发现，该黄土的崩解过程可以划分为浸湿、软化和塌落3个阶段，前两个阶段持续的时间较短且崩解很弱，崩解主要集中在第3个阶段。由各组崩解曲线得出黄土的崩解速率与水温呈正相关，与土样尺寸、初始含水率呈负相关；pH值介于5.5~6.5以及9.5~10.5时，黄土的崩解速率较高；而盐度对黄土的崩解速率影响不大。此外，黄土的崩解特征与自身的结构、颗粒成分、胶结物等密切相关。
关键词:
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崩解特性
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影响因素
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含水率
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水温
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酸碱度
Abstract:
To study the disintegration characteristics and mechanisms of loess, this paper examines the Malan loess of Heifangtai by using the self-developed disintegration instrument. A series of disintegration experiments with undisturbed loess are conducted. Six probable impact factors of disintegration are selected, including pore diameter, sample size, initial moisture content, water temperature, pH value and salinity. The experiments are carried out by using the variable-controlling approach, the whole process of disintegration is recorded, the curve of disintegration is drawn, and each corresponding disintegration velocity is calculated. Finally, the correlation between the disintegration velocity and the impact factors is obtained by fitting the experimental data. The experiment results also show that the disintegration procedure of the loess can be divided into three stages, including the water absorption stage, softening stage and collapsing stage. The duration of the first two stages is very short, and disintegration is weak at this time because it occurs mainly in the third stage. According to these curve of disintegration, it is found that the disintegration velocity is positively correlated with the pore diameter and water temperature but is negatively correlated with the sample size and initial moisture content, and the corresponding value of R2 are 0.897 3, 0.854 4, 0.950.3 and 0.970.9 When the initial moisture content is under 10%, the disintegration velocity changes in small ranges, when the initial moisture content is between 10% and 20%, the disintegration velocity decreases sharply with increasing moisture content, and when the initial moisture content is greater than 20% and gets close to saturation, the disintegration velocity is gradually close to a stable value. When pH is between 5. 5 and 6.5 or 9.5 and 10.5, the disintegration velocity is high. The effect degree of salinity is small. In addition, the disintegration is related to soil structure, grain size composition, cement, and so on.
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