Simulation study of rockfall deposition based on UAV-PCAS-PFC: a case study on the rockfall deposition of Xiaomaopo in Kaiyang County

• Published in: Arabian journal of geosciences 2022-03, Vol.15 (6), Article 468
• Main Authors: Xu, Jinxing, Yang, Genlan, Qin, Yigen, Liang, Feng
• Format: Article
• Language: English
• Subjects: Accumulation; Area; Composition; Deformation; Deposits; Digital imaging; Direction; Dolomite; Dolostone; Earth and Environmental Science; Earth science; Earth Sciences; Elevation; Image processing; Object recognition; Original Paper; Research methods; Risk assessment; Rockfall; Rocks; Sediments; Shape; Simulation; Statistical methods; Structural hierarchy; Surveying; Three dimensional flow; Unmanned aerial vehicles
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-022-09740-w

This study developed a rockfall simulation method based on the actual rock block accumulation size. The terrain data and orthophoto map were obtained based on post-event high-precision UAV aerial image data, and digital image processing methods were used to identify the rock block sizes of rockfall deposits. The sizes of the sedimentary rockfall blocks were recorded in a field survey. The distribution law of the rock block size was compared using field statistics and image recognition. Based on the topographic data and rock block accumulation size, a three-dimensional (3D) particle flow code was used to simulate the deposition process and characteristics of the rockfall. The research results showed that the distance of the rockfall deposit is approximately 480 m and the average width is approximately 86 m. Rockfall deposits were mainly composed of white and gray-white dolomite blocks, which were deposited along the slope in a strip shape with a deposition direction of 142°. The elevation of the upper deposit near the source area was 1290 m, and the elevation difference was 180 m. The rockfall deposit forms the main deposition area, secondary deposition area, and rockfall area. The deposits are mainly composed of small-sized rock blocks, and their rock block size generally obeys the inverse model. Along the stacking direction, the proportion of the small-sized rock blocks shows a decreasing trend. The proportions of medium-sized and large-sized rock blocks show a bimodal situation with two peaks, and the change curve is an irregular “M” shape. The simulation results showed that the slope movement process, from obvious deformation to sedimentation after instability, is about 22.5 s, and the main slip time is about 18.0 s. Along the depth direction, as the depth increases, the composition of small-sized rock blocks increases, while the composition of large-sized and medium-sized rock blocks decreases. However, a reverse granular hierarchical structure appears in the sediments. The research results are consistent with the actual accumulation status of rockfalls, and related research methods provide a reference for quantitative risk assessment of rockfalls.