考虑结构性的冻融作用对黄土湿陷系数的影响

结构性是黄土的基本属性，黄土的湿陷特性与其结构性之间有着必然的联系。针对冻融作用对不同结构性黄土湿陷性的影响，以水泥作为模拟土颗粒间的联结材料制备了人工结构性土，开展了不同水泥含量的人工结构性土与相应的原状土、重塑土的湿陷试验，分析了结构性、冻融作用、初始含水率、湿重度及荷载大小对湿陷系数的影响规律。试验结果表明：冻融前后，人工结构性黄土的湿陷系数均比原状土、重塑土的湿陷系数小，且随着水泥含量的增加，湿陷系数有所减小；冻融之后，各土样的湿陷系数几乎均有所增加，但增加的程度和土样初始结构、含水率、干密度（压实系数）及竖向荷载关系密切，尤其当含水率接近最优含水率和土样为重塑土或水泥含量较低的人工结构性土时，冻融后湿陷系数增大幅度显著。在标准荷载200 kPa下，冻融前后原状土、重塑土的湿陷系数与其湿重度之间基本呈较好的线性负相关关系，而人工结构性黄土湿陷系数与湿重度之间并不呈线性关系；竖向荷载为50 kPa时，重塑黄土和5%水泥含量黄土的湿陷系数与冻融次数之间存在着较好的对数关系。以水泥作为土颗粒间联结材料，制备的人工结构性土是否能很好地代替原状土反映结构性黄土的湿陷特性，还需更进一步深入研究。

The influence of freeze-thaw action on loess collapsibility coefficient considering soil structure

Structural characteristic is a basic property of loess, and there is a connection between loess collapsibility and its structure. This paper aims at studying how freeze-thaw action affects loess collapsibility with different structural characteristics. A series of collapsibility experiments was performed on artificially structured loess, undisturbed loess and remolded loess, with the use of cement as connection medium among soil particles to prepare artificially structured loess samples. Experimental results show that the collapsibility coefficient of artificially structured loess is less than that of the undisturbed loess and remolded loess before and after freezing-thawing process. The collapsibility coefficient decreases with the increase of cement content. After freezing-thawing, the collapsibility coefficients of most loess samples increase. Especially, for remolded loess and artificially structured loess with low cement content, the increase of collapsibility coefficient is more evident when the water content is close to the optimum water content. Moreover, the increase of collapsibility coefficient is also closely related to the initial structure, water content, dry density and vertical load. Regarding undisturbed loess and remolded loess, a significant negative linear correlation is found between the collapsibility coefficient and unit weight under standard load, 200 kPa. However, for artificially structured loess, it is not the case. Furthermore, for remolded loess and artificially structured loess with 5% cement content, there is a good logarithmic relationship between the collapsibility coefficient and number of freeze-thaw circle under a load of 50 kPa. Also, further research is needed to study whether the original loess can be replaced by artificially structured loess mixed with cement to reflect the collapsibility of structural loess.