湖北郧阳膨胀土滑坡成因机制分析——以黄家槽滑坡为例

Analysis of Genesis Mechanism of Expansive Soil Landslide in Yunyang, Hubei—Taking Huangjiacao Landslide as an Example

近年来,每逢暴雨季节,地质灾害频发,尤以堆积体失稳为主,此类型的滑坡大多发生于城镇地区,造成的危害极大,膨胀土滑坡为其中一个典型。本文对湖北郧阳区黄家槽滑坡这一典型来分析研究膨胀土滑坡的形成机制,这对膨胀土地区的滑坡预防和治理有着重大的意义。通过大比例工程地质测绘及工程钻探、力学试验等方法手段对黄家槽滑坡的失稳过程进行研究得出:黄家槽滑坡覆盖层土体具有弱膨胀性,具有浅层性、平缓性、季节性。在人工开挖的基础上形成了大量的人工切坡,使得膨胀土质的边坡临空,在持续的强降雨作用下由于膨胀土特有的多裂隙性质,使得雨水易渗入,土体遇水产生胀缩软化,物理性质改变强度大大降低,地下水位的上升在基覆界面处会形成饱和带,使整个坡体的应力发生改变,抗滑力大大降低,从而沿基覆界面(滑面)发生蠕动变形,随着持续的降雨,其变形会随之增大,促使整个坡体失稳。

In recent years, geological hazards frequently occur in the heavy rain season, especially the instability of sedimentary bodies. Most of the types of landslides occur in urban areas, causing great harm. Expansive soil landslides are one of the typical examples. This paper analyzes the formation mechanism of the expansive soil landslide based on the typical Huangjiacao landslide in Yunyang District, Hubei, which has great significance for the prevention and treatment of landslides in the expansive soil area. The research on the instability process of Huangjiacao landslide based on a large proportion of engineering geological mapping, engineering drilling, and mechanical tests shows that the soil of Huangjiacao landslide is weakly expansive, shallow, gentle, seasonal. Due to the formation of a large number of artificial slopes on the basis of artificial excavation, the expansive soil slope is facing the sky. Under the continuous heavy rainfall, due to the multi-fissure nature of the expansive soil, rainwater is easy to infiltrate and the soil is in contact with water. Expansion and contraction softening, physical strength changes greatly reduce the intensity, the rise of the groundwater level will form a saturation zone at the interface of the foundation, change the stress of the entire slope, greatly reduce the anti-sliding force, and thus along the interface of the foundation (sliding surface), creeping deformation occurs, and the deformation will increase with the continuous rainfall, which promotes the instability of the entire slope.