Abstract
Red beds refer to the collective term for red rock series deposited throughout various geological historical periods, represent typical "slip-prone strata", and are prone to triggering clustered geological hazards during intense rainfall events. A review of research findings on the development, distribution, and primary characteristics of red beds both domestically and internationally reveals that red bed properties are controlled by sedimentary formation, and that the physical-mechanical and hydro-physical properties of red bed rocks are intimately correlated with their depositional environments. Red bed rocks exhibit pronounced rheological behavior and hydrophilicity, readily undergoing expansion, disintegration, argillization, and softening upon water ingress. This study analyzes and summarizes the primary categories of geological hazards in red bed regions, with particular emphasis on elucidating the genetic mechanisms of translational landslides in interbedded sandstone-mudstone areas and gentle, shallow soil landslides. The results demonstrate that hydrostatic pressure generated by rapid rainwater infiltration into vertical fractures within sandstone during rainfall events represents the principal driving force for translational landslides. Concurrently, long-term argillization and water-saturated softening of sandstone-mudstone contact interfaces or weak interlayers by groundwater substantially reduce basal slip surface strength, constituting another primary cause of large-scale translational landslide occurrence. Furthermore, the distinctive slope hydrogeological conditions arising from the unique lithological combination of interbedded sandstone-mudstone constitute another significant factor predisposing these areas to landslides. In gentle red bed regions, the existence of a depth of atmospheric influence within slope residual deposits and interface effects at the bedrock-cover interface represent the primary causes of clustered shallow soil landslides during intense rainfall events, which consequently govern the thickness of the sliding mass. Finally, risk prevention and control measures for red bed geological hazards are discussed. It is concluded that establishing physical early warning models through integrated mathematical-mechanical analysis, field monitoring, and laboratory testing constitutes an effective approach for red bed landslide early warning. Moreover, landslide mitigation in red bed regions should adhere to the principle of prioritizing drainage measures while employing anti-slide retaining structures as supplementary measures.
Full Text
Preamble
Study on Red Beds and its Geological Hazards
XU Qiang¹, TANG Ran²,³
¹State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
²School of Architecture and Civil Engineering, Chengdu University, Chengdu 610106, China
³Sichuan Engineering Research Center for Mechanical Properties and Engineering Technology of Unsaturated Soils, Chengdu University, Chengdu 610106, China
Abstract
Red beds refer to the collective term for red-colored rock series deposited during various geological historical periods and represent typical "slide-prone strata" that readily generate clustered geological hazards during intense rainfall events. By synthesizing domestic and international research on the development, distribution, and primary characteristics of red beds, this study reveals that the properties of red beds are fundamentally controlled by their sedimentary formation. The physical-mechanical properties and hydro-physical characteristics of red bed rocks are closely related to their depositional environment. Red bed rocks exhibit pronounced rheological behavior and strong hydrophilicity, readily undergoing swelling, disintegration, mudding, and softening upon water exposure.
This paper analyzes and summarizes the main types of geological hazards in red bed regions, with particular emphasis on the formation mechanisms of translational landslides in sandstone-mudstone interbedded areas and gentle shallow soil landslides. The results demonstrate that hydrostatic pressure generated by rainwater rapidly infiltrating vertical fractures in sandstone during rainfall events constitutes the primary driving force for translational landslides. Simultaneously, long-term mudding and water-saturated softening of sandstone-mudstone contact interfaces or weak interlayers by groundwater significantly reduce the shear strength of basal sliding surfaces, representing another major cause of large-scale translational landslides. Additionally, the unique hydrogeological conditions created by the special lithological assemblage of sandstone-mudstone interbeds constitute an important predisposing factor for landslide susceptibility.
In gentle red bed areas, the presence of an atmospheric influence depth within slope residual deposits and interface effects at the bedrock-cover interface are identified as the main causes of clustered shallow soil landslides during heavy rainfall, which also govern the thickness of sliding masses. Finally, the paper discusses risk prevention and control measures for geological hazards in red beds, proposing that establishing physical early warning models through integrated mathematical-mechanical analysis, field monitoring, and laboratory testing represents an effective approach for red bed landslide early warning. For landslide mitigation in red bed regions, the principle of prioritizing drainage with supplementary anti-slide support should be consistently adopted.
Keywords: slope engineering; red beds; geological hazards; formation mechanism; translational landslide; shallow soil landslide