Abstract: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.
