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Copyright of Journal of Natural Disasters is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Realizing quantitative evaluation of disaster reduction benefits of debris flow retaining dams has important theoretical and practical significance for optimizing engineering design and protecting the safety of people's lives. and property. The paper uses numerical simulation methods to obtain the mud depth, flow velocity, and range of debris flow under different operating conditions, establishes two risk evaluation index systems based on the area of high risk level and the total risk degree, proposes a quantitative evaluation method for the disaster reduction benefits of retaining dams, and conducts an empirical study using the Chutougou debris flow as an example. According to the evaluation method for disaster reduction benefits of retaining dams, it is possible to analyze the disaster reduction benefits of the proposed and existing projects and their combinations, determine whether they have achieved the disaster reduction goals, and compare and quantify the importance of different projects in disaster reduction, which can provide a basis and reference for the construction and improvement of debris flow retaining dams. The disaster reduction benefits per unit height can reflect the value of risk reduction per meter of retaining dam heightening, and can be applied to the determination of optimal engineering combination scheme of debris flow retaining dams. The change rule of the total risk degree and the disaster reduction benefits of the area with high risk level is consistent, indicating that both risk assessment methods can reflect the disaster reduction benefits of the combination of retaining dams and their changes. [ABSTRACT FROM AUTHOR]

The dangerous rock mass is widely distributed in southwest China, and is easy to formate collapse for many times. In order to study the collapse disasters reported in the terrain, the accumulation of subsequent collapse rockfalls characteristics, this paper, by using multiphase collapse simulation method, can reflect the changing situation and the threat range of the deposit after many times collapse according to certain probability, and supplement the deficiency of the conventional calculation result of once collapse of stones. It provides a scientific basis for the prevention and control of geological disaster in the study area in the following period. This paper takes the Xujiadabang collapse in Sinan County, Guizhou Province as an example. The multi-stage numerical simulation of unstable rock collapse is studied based on laboratory tests and numerical simulation, combined with GIS technology and 3D collapse software. The numerical simulation results of four stages of collapse by using the characteristic parameters obtained from physical experiments are in good agreement with the field investigation results. It is found that almost all of the large size rockfalls and most of the small size rockfalls are deposited in the area with a slope less than 35°. More than 90% of the rockfall deposits in the 30 m buffer zone on the abandoned road surface, that is, 100 m away from the residential area. The percentage of rockfall deposits in the direction of the abandoned road toward the cliff shows an upward trend. The nearest large particle size rockfall is mainly 60 m away from the residential area, and the possibility of threatening the residential area is low. A small number of small particle size rockfalls will fall to the residential area. The research ideas and technical methods in this paper have reference values and significance for the study of multi-stage dangerous rockfall. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Disasters is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Natural Disasters is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Natural Disasters is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Loess is a kind of Quaternary loose deposits. There are many primary and secondary pores and cracks in the loess, which provide preferential channels for water to enter the soil and form preferential infiltration phenomenon. This water movement mode is called preferential flow. The existence of preferential infiltration and preferential flow is one of the main causes of landslide and other loess geological disasters, so it is necessary to study the phenomenon of preferential infiltration. Based on the discussion of the classification of loess dominant structural planes by previous scholars, this paper puts forward the classification method of loess preferential channels, then discusses the preferential flow classification of domestic and foreign scholars and the main research methods, and analyzes their advantages and disadvantages. This paper summarizes the main infiltration models of the current preferential flow and the characteristics of the governing equations representing the models, analyzes and discusses the deficiency of present research and the development direction in the future at the end. [ABSTRACT FROM AUTHOR]

In view of the spatial scale of threat and potential risks caused by debris flow under four extreme rainfall conditions, risk assessments of debris flow hazard in Maiduo Gully, Chaya County, Tibet were carried out, using a single building as an evaluation unit. Assessments include the risk division, vulnerability analysis and risk assessment of debris flow. This paper describes a whole workflow of a refined risk assessment. Firstly, based on a three dimensional geological model acquired from UAV, the FLO⁃2D software was used to simulate the process of debris flow outbreaking in Maiduo Gully under four extreme rainfall conditions(10%,5%,2%,1%),and the risk zones were divided. Then, analyzed the vulnerability of buildings and population in the affected area according to on site data. After that, took a single building as the evaluation unit, risks and vulnerability were normalized, and to eventually get the risk zones of building and population in study area, overlay analysis was applied on ArcGIS Desktop. These evaluation results are able to provide scientific reference to the works of local geological disasters and risk control, and the evaluation workflow can be used as a reference for future refined quantitative risk assessments of debris flow hazard as well. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)