膨胀土是由粘粒的亲水性矿物成分组成的一种高塑性粘土,在我国北方地区,这种土质在夏季与冬季有着不同的物理力学特性,往往没有引起人们的足够重视,给已建的房屋造成不同程度的危害。在冬季,膨胀土具有冻土的物理特性,由于夏季雨水较多,水分贮存在土粘粒里面,在大气的影响下,根据水分迁移机理,水分向上冻结成锋面,聚集成冰夹层。随着冰晶体的逐渐扩大,引起土体冻层膨胀而产生冻胀力,地基土体隆起。冻胀力产生的过程,就是有效压力消失,代以膨胀力的内力 Expansive soil is a kind of highly plastic clay composed of hydrophilic mineral components of clay. In northern China, this soil has different physical and mechanical properties in summer and winter, and it often fails to attract people’s attention. The houses cause different degrees of harm. In winter, expansive soils have the physical characteristics of frozen soils. Because there is more rainwater in the summer, the water is stored in the clay particles. Under the influence of the atmosphere, according to the water migration mechanism, the water freezes up to the front and gathers into the ice sandwich. As the ice crystals gradually expand, the frozen layer of the soil expands and the frost heave force is generated, and the foundation soil swells. The process of frost heaving force is the disappearance of effective pressure and the internal force of expansion force