Debris flows are the main geological hazards in the Moxi basin, which locate on the eastern slope of the M.T Minya Konka, Sichuan province, southwestern of China. The location of 49 debris flow gullies have been ident...Debris flows are the main geological hazards in the Moxi basin, which locate on the eastern slope of the M.T Minya Konka, Sichuan province, southwestern of China. The location of 49 debris flow gullies have been identified and mapped from the 1:50000 scale through the extensive field survey across the Moxi basin. The historical events data were collected from documents and visit to local residents, and were used as the basis for frequency analysis. Anymore, topographic features of debris flow gullies have been calculated using GIS software. The analysis showed that 73.5% of the debris flow gullies are not randomly distributed but concentrated directly adjacent to the western side of Moxi fault, and only 26.5% are located to the eastern side. The numbers, frequency, catchments area, gully length, gully slope ratio of these debris flow gullies in Moxi basin were affected by the glaciations and geological activity. The results show potential activity of debris flow in Moxi basin is strong, this research is essential to debris flow hazards mitigation.展开更多
Many popular models have been proposed to study the fractal properties of the pores of porous materials based on mercury intrusion porosimetry(MIP).However,most of these models do not directly apply to the small-micro...Many popular models have been proposed to study the fractal properties of the pores of porous materials based on mercury intrusion porosimetry(MIP).However,most of these models do not directly apply to the small-micro pores of loess,which have a significant impact on the throat pores and tunnels for fluid flow.Therefore,in this study we used a combination of techniques,including routine physical examination,MIP analysis,and scanning electron microscope(SEM)image analysis,to study these small-micro pores and their saturated water permeability properties.The techniques were used to determine whether the fractal dimensions of six MIP fractal models could be used to evaluate the microstructure types and permeability properties of loess.The results showed that the Neimark model is suitable for analysis of small-micro pores.When applied to saturated water permeability,the results from this model satisfied the correlation significance test and were consistent with those from SEM analysis.A high clay content and density cause an increase in the number of small-micro pores,leading to more roughness and heterogeneity of the pore structure,and an increase in the fractal dimensions.This process further leads to a decrease in the content of macro-meso pores and saturated water permeability.Furthermore,we propose new parameters:the*Ellipse and its area ratios(*EAR).These parameters,coupled with 2D-SEM and 3D-MIP fractal dimensions,can effectively and quantitatively be used to evaluate the types of loess microstructures(from typeⅠto typeⅢ)and the saturated water permeability(magnitude from 1×10^(-4)cm/s to 1×10^(-5)cm/s).展开更多
文摘Debris flows are the main geological hazards in the Moxi basin, which locate on the eastern slope of the M.T Minya Konka, Sichuan province, southwestern of China. The location of 49 debris flow gullies have been identified and mapped from the 1:50000 scale through the extensive field survey across the Moxi basin. The historical events data were collected from documents and visit to local residents, and were used as the basis for frequency analysis. Anymore, topographic features of debris flow gullies have been calculated using GIS software. The analysis showed that 73.5% of the debris flow gullies are not randomly distributed but concentrated directly adjacent to the western side of Moxi fault, and only 26.5% are located to the eastern side. The numbers, frequency, catchments area, gully length, gully slope ratio of these debris flow gullies in Moxi basin were affected by the glaciations and geological activity. The results show potential activity of debris flow in Moxi basin is strong, this research is essential to debris flow hazards mitigation.
基金supported by the China Geological Survey Project(No.DD20190642)the Shaanxi Provincial Key Research Program of China(No.2019ZDLSF07-07-02)。
文摘Many popular models have been proposed to study the fractal properties of the pores of porous materials based on mercury intrusion porosimetry(MIP).However,most of these models do not directly apply to the small-micro pores of loess,which have a significant impact on the throat pores and tunnels for fluid flow.Therefore,in this study we used a combination of techniques,including routine physical examination,MIP analysis,and scanning electron microscope(SEM)image analysis,to study these small-micro pores and their saturated water permeability properties.The techniques were used to determine whether the fractal dimensions of six MIP fractal models could be used to evaluate the microstructure types and permeability properties of loess.The results showed that the Neimark model is suitable for analysis of small-micro pores.When applied to saturated water permeability,the results from this model satisfied the correlation significance test and were consistent with those from SEM analysis.A high clay content and density cause an increase in the number of small-micro pores,leading to more roughness and heterogeneity of the pore structure,and an increase in the fractal dimensions.This process further leads to a decrease in the content of macro-meso pores and saturated water permeability.Furthermore,we propose new parameters:the*Ellipse and its area ratios(*EAR).These parameters,coupled with 2D-SEM and 3D-MIP fractal dimensions,can effectively and quantitatively be used to evaluate the types of loess microstructures(from typeⅠto typeⅢ)and the saturated water permeability(magnitude from 1×10^(-4)cm/s to 1×10^(-5)cm/s).
