Shear Test Mechanical Characterization Of Red Clay On Slope Field In Hunan Province Under Hot-Humid-Acid Conditions

As a basic geotechnical engineering material,red clay is widely distributed in the monsoon climate region of southern China,constituting or participating in the formation of a large number of shallow landslide bodies in Hunan province.In order to explore the landslide instability mechanism,the primary task is to study the mechanical properties of the sliding body material.Also,because of the new normal environment with frequent extreme weather,more factors need to be clear such as moisture content,temperature and acid combined influence on shear strength of soil to guide the construction of traffic engineering under complex environment in the disaster prevention and control of slope instability.Therefore,the typical red clay of slope in Hunan province was selected as the research object,and the mechanical characteristics under complex environment were studied by undrained and unconsolidated fast shear test.By means of XRD test,electron microscope scanning and other means,the deformation characteristics were analyzed from the mineral composition and microscopic scale,and the following conclusions were drawn:1.Through direct shear test,the shear strength features of red clay under different acid environment,temperature and moisture content was analyzed.The results showed that the increase of moisture content of soil sample would reduce the shear strength of red clay,while the increase of temperature would weaken the influence of moisture content.In other words,the increase of temperature would improve the shear strength of red clay.Also,in the weak acid environment,the strength of red clay can be improved.The temperature value,15?,and the pH value,5,can be seen as critical values,the shear strength of red clay is highest at this point.With the increase or decrease of temperature,the maximum shear strength of pH value change into 3,when the moisture content is lower,the greater the vertical stress,the more obvious this phenomenon.2.The slope of red clay mineral composition is tested by XRD,and the mesoscopic structure features and the condition of acid red clay chemical composition are observed with the help of electron microscope scanning.The factors influence the shear strength can be concluded as follow: In the hot and humid acid environment,the strength of red clay are mainly dominated by the reaction of the chemicals,the change of soil structure and the change of the electric double layer.3.The statistical method was used to analyze the significant influence of hot and humid acid factors on the shear strength of red clay on sloping land.The results show that the factors influencing the strength of red clay are water content,acid strength and temperature in turn.