黑方台地区崩塌灾害发育类型和发育机制分析

以甘肃省永靖县黑方台地区实地调查为基础,通过野外勘察黄土崩塌变形破坏特征及总结地质现象,并结合数据统计分析进行研究,得出黑方台地区崩塌地质灾害的分布特点,并且发现凸型和阶梯型坡面更容易发生崩塌灾害。崩塌发育因素可分为2方面,一方面是自然因素,包括地形地貌,地层构造和水文地质条件;另一方面是人为因素,主要是人类工程活动。天然条件下,斜坡在自重或其他因素作用下,后缘黄土垂直节理或裂隙受拉张作用力开始破裂,并向深部扩展,随着水流下渗,逐渐形成贯通面,潜在崩塌体中心外移,最终形成崩塌。黑方台地区崩塌灾害按崩塌物质成分分为黄土崩塌和基岩崩塌2类,按崩塌发生的主控因素分为自然型崩塌、人为型崩塌和人为—自然复合型崩塌3类,而大量的节理裂隙发育是发生崩塌灾害的内在因素。通过野外调查,根据动力形成机制分析,在自然因素和人为因素影响下,将黑方台地区崩塌形成方式分为4种,并阐述其发育机制。

Analysis on the Developmental Types and Development Mechanism of Collapse Disasters in Heifangtai Area

Based on the field investigation of Heifangtai area, the deformation characteristics of the loess collapse geological phenomena, combining with statistical analysis, the distribution characteristics of geological disasters in Heifangtai area have been introduced. It is found that convex and ladder-type slope are easy to happen collapse disasters. The factors which will cause collapses can be divided into two aspects, one is natural factors, including topography, stratigraphic structure and hydrogeological conditions; the other is human factors, mainly human engineering activities. Under natural conditions and the action of self-weight or other factors, vertical joints or cracks by the tensile force will happen in the trailing edge loess, then widen to the deep part. Accompanying with water infiltration, through plane will be formed gradually. The potential collapse center will migrate to surrounding areas, and form collapses eventually. The collapses in Heifangtai area can be divided into loess collapse and bedrock collapse according to the materials of collapses. According to main controlling factors of collapses, it is divided into natural type collapse, man-made collapse and man-made compound type collapse. A large amount of joint fissures are intrinsic factor of collapse. Through field investigation, according to the analysis of dynamic formation mechanism, under the influence of natural factors and human factors, the formation types of collapses in Heifangtai area can be divided into four kinds, and the developement mechanism has been introduced as well.