冻融作用对黑土力学性质的影响研究

反复的冻融循环会通过改变土壤黏聚力、内摩擦角等土壤力学性质而使其侵蚀加剧。探讨了冻融循环作用对土壤黏聚力及内摩擦角的影响,从冻融机理上分析了冻融作用对土壤抗蚀性的影响机制。以黑土为试验对象,考虑冻融循环周期和土壤含水率2个影响因素,通过室内冻融试验研究了黑土黏聚力c和内摩擦角ψ的变化规律。结果表明,冻融作用对黑土黏聚力影响较大,而对内摩擦角影响较小。随着冻融循环次数的增加,同一含水率下,黑土黏聚力c呈减小趋势,3次冻融循环以后,c值趋于稳定。在冻融循环次数一定时,随着土壤含水率的增加,黑土黏聚力c呈先减小后增大的趋势。在冻结温度一定时,1次冻融循环对土壤黏聚力c的扰乱较大,其后扰动程度则基本不变。与土壤黏聚力不同,土壤内摩擦角在整个冻融循环过程中没有明显变化。

Effects of Freeze-Thaw Cycle on Mechanical Properties of Black Soil

Repeated freeze-thaw cycles cause changes in soil cohesion and internal friction angle,increasing the erodibility of the soil.This study discussed the variations of soil bulk cohesion and internal friction angle in the freeze-thaw cycles and analyzed the freeze-thaw effects on soil anti erodibility. The black soil was selected as the study object.The changing trend of cohesion and internal friction angle of the soil were invest-igated through indoor freeze-thaw experiments with consideration of different freezing cycles and various soil moisture contents. The results show that freeze-thaw cycles affected greatly the soil cohesion and slightly the internal friction angle. With increasing numbers of freeze-thaw cycles, soil cohesion decreased and then achieved a stable state after three freeze-thaw cycles.With the increase of soil moisture,soil cohesion reduced and then increased in individual freeze-thaw cycles. At same freeze-thaw temperature, soil cohesion was affected greatly in the first freeze-thaw cycle, and very little in the following cycles. In contrast to soil cohesion, internal friction angle did not change significantly in the whole process of freeze-thaw cycles.