Research on the Geometric Characteristics and Formation Mechanism of Loess Collapse Based on UAV Aerial Survey and Numerical Simulation

In response to the complex formation mechanism of loess landslide disasters and the insufficient accuracy of traditional investigation methods, this study proposes a "space ground number" collaborative analysis method. The typical loess landslide body that occurred in Yangjiagou Town Industrial Park, Mizhi County on September 14, 2023, is taken as the research object. Three dimensional terrain data with centimeter level resolution is obtained through unmanned aerial vehicle aerial survey technology to reconstruct the geometric shape characteristics of the landslide body; Reveal the characteristics of controlling structural planes and stratigraphic combinations through on-site geological surveys. Based on the mixed finite element discrete element numerical simulation (Y-Mat), a dual scale model considering the real geometric shape and structural plane distribution is constructed. Through simulation, it is revealed that due to the influence of terrain and crack water conduction, the slope foot softens when encountering water, the strength decreases, and the upper loess body is pulled to deform. When the deformation accumulates to a certain extent, it collapses downwards along the original through water conduction cracks. During the falling process, some loess disintegrates and accumulates within a certain range of the slope foot, forming loess blocks and loose soil of different sizes, which impact the buildings at the slope foot and cause them to collapse. The research results can provide multi-source data fusion analysis methods and technical support for the study of the evolution mechanism of landslide geological hazards in the Loess Plateau.