Three-Dimensional Topography of Debris-Flow Fan

摘要

Study on debris-flow fan configurations lays the groundwork for hazard zone mappings of debris flow disasters. This paper aims to identify the morphological similarity of debris-flow fans based on a series of laboratory experiments and field investigations. The maximum length L_c, width B_m, and thickness Z_o of debris-flow fans are adopted as the characteristic parameters in the analysis of morphological similarity of debris-flow fans. This analysis demonstrates that the nondimensional longitudinal and transverse profiles of debris-flow fans can be described by Gaussian curves, while a circular curve can be used to fit the nondimensional plan form of the debris-flow fans. By combining the three nondimensional curves mentioned above, the volume any of a debris-flow fan can be related to the maximum length L_c, maximum width B_m, and maximum thickness Z_o by any=αL_cB_mZ_o, via an empirical coefficient α. The parameter α is approximately 0.275 for a natural stony debris-flow fan and greater than 0.275 for a natural mud debris-flow fan. In addition, the three-dimensional topography of debris-flow fans can be easily derived based on the parameters L_c, B_m, and Z_o using three morphological similarity formulae.