冻融循环对黄土二次湿陷特性的影响研究

在黄土地区公路路基建设中, 通常会采用预湿陷等办法来对湿陷性黄土进行处理以达到工程要求.但是在季节冻土区, 处理过的黄土路基却在运营几年后, 仍发生大量的不均匀沉降、 塌陷等病害.为分析冻融循环作用对黄土二次湿陷的影响, 采用室内试验方法, 使大体积黄土样品先完成一次湿陷, 再进行冻融循环和黄土二次湿陷.试验结果表明: 重塑黄土与原状黄土的二次湿陷系数随着冻融循环次数的增加趋向于同一个特定值; 重塑黄土和原状黄土的二次湿陷系数皆大于0.015, 说明二者皆满足湿陷条件, 在冻融条件下具有二次湿陷性.

Research on the Secondary Collapse Properties of Loess under Freeze-Thaw Cycle

In the construction of subgrade in loess areas, some methods like pre-collapse are always taken to make the subgrade more stable. However, in seasonal frozen soil areas, there are some loess subgrades having disease, such as vast uneven settlement or collapse, after running a few years. In order to study and analyze the reason how the freeze-thaw cycle influence the secondary collapse of loess, experiments were done in the laboratory. First, loess specimen was collapsed in a big volume, and then the specimen experienced freeze-thaw cycles and finally experienced second collapse. It is found from these experiments that the intact loess and the remolded loess's coefficients of secondary collapse come to a same value gradually with freeze-thaw cycle increasing; both the intact loess and the remolded loess's coefficients of secondary collapsibility are larger than 0.015, which is the standard to identify whether the loess has the ability to collapse, so both the intact loess and the remolded loess have the ability of secondary collapse under freeze-thaw cycle.