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Zheng Chen received his PhD degree in Geotechnical Engineering from the University of Chinese Academy of Sciences in 2022, with substantial training and research experience at the Institute of Mountain Hazards and Environment, Chinese Academy of Sciences (2016-2022), and the Swiss Federal Research Institute WSL, Switzerland (2019-2022) during his doctoral studies. He has been an Assistant Research Fellow/Professor at the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, since 2022, and presently holds a postdoctoral fellowship at WSL (ETH-domain). His research focuses on sediment transport processes and geophysical mass flows, with particular interests in (1) bedload transport monitoring with acoustic systems, (2) debris flow/flood dynamics, and (3) shock wave dynamics in granular flows.
Outline
Hazardous geophysical granular flows, such as debris flows and rock avalanches, can exert intense impact forces on obstacles and threaten downstream structures located in their paths. Installing protective structures can mitigate damage, but quantifying their influence on flow evolution and impact loading remains challenging. This study investigates the interactions of granular shock waves (GSWs) generated in front of two cylindrical obstacles with varying spacings through chute experiments and discrete element modeling. Impact pressure sensors were mounted on the upstream surface of each cylinder and on the chute bed to measure dynamic impact pressures in the GSW region. Granular flow velocity and depth were obtained using image processing. Results demonstrate that cylinder spacing significantly influences the geometric characteristics of GSWs. Runup increases with steady-state Froude number (Frsteady) but decreases as spacing narrows. The granular vacuum length grows with bed slope but decreases significantly with decreasing cylinder spacing. Impact pressures on the cylinders and the chute bed increase linearly with Frsteady. Low-frequency power spectral density (PSD) is positively correlated with Frsteady, whereas centroid frequency and pressure impulse counts exhibit low sensitivity to Frsteady. The dimensionless impact pressure coefficient (α) decreases nonlinearly with increasing Froude number (Fr). At low Fr, α values for dry granular flows are lower than those for debris flows, but the difference diminishes at higher Fr. These findings may improve our understanding of granular flow-obstacle interactions and might help to design protective structures.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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