Study On The Correlation Between Physical And Mechanical Properties And Microstructures Of Red-bed Sliding Zone Soils In Southwest China

In this paper,the landslide sliding zone soil in Meigu River Hydropower Station Camp is taken as the research object.By means of investigation,sampling,laboratory test and data analysis,the physical and mechanical characteristics and micro-structure characteristics of the sliding zone soil at three different locations in the landslide area are systematically studied.Finally,the physical and mechanical parameters and micro-structure parameters are combined to study the variation law and the relationship between them.In this paper,the basic physical properties,particle size distribution,mineral and chemical characteristics and mechanical strength characteristics of sliding zone soil are obtained through a series of tests,including conventional physical properties test,particle size analysis,XRD diffraction test,X-ray fluorescence spectrum analysis test,direct shear test and repeated shear test.The Micro-Parameters are extracted by SEM scanning electron microscopy test and IPP image processing technology to quantitatively study sliding.The main conclusions are as follows:?1?With the increase of burial depth,the content of fine grains in slip zone soils of 2#,26#and 34#piles increase gradually.The slip zone soil contains quartz,feldspar,calcite,kaolinite,illite and illite,and the content of quartz and illite is higher.The main chemical compositions of the slip zone soil are SiO₂?Al₂O₃?F₂O₃?K₂O?TiO₂?MgO?CaO,etc.?2?The shear strength parameters and residual strength parameters of sliding zone soils with three different piles,2#,26#and 34#,show obvious regularity due to the different particle size distribution.Fine particle content is positively correlated with cohesive force CD value,negatively correlated with internal friction c_d,residual cohesive force Cr and residual internal friction?r.The creep test of sliding zone soil shows that the long-term shear strength is 1/5 of the short-term strength.?3?Under SEM scanning electron microscopy,parallel linear scratches were observed on the sliding surface of the sliding zone soil,and the particles arranged closely,showing a laminated structure,with a plum-blossom-shaped sheet and a high degree of orientation.The cross-section of the sliding zone soil presented a turbulent structure,and the structural units mainly consisted of flake and flat particles,which existed in a plane-to-plane contact mode.?4?The SEM images of the cross sections of sliding zone soils at three different locations treated by IPP show that under the same vertical pressure,the average diameter of pore and particle decreases with the increase of fine particle content;the porosity increases with the increase of fine particle content;the pore morphology ratio increases with the increase of fine particle content;and the fractal dimension of pore and particle increases with the increase of fine particle content.The roundness of particles decreases with the increase of the content of fine particles,and the dispersion index of particles decreases with the increase of the content of fine particles.With the increase of vertical pressure,the average diameter of pore and particle decreases gradually;the porosity decreases gradually;the pore morphology decreases gradually;the pore morphology ratio has no obvious change law;the particle morphology ratio decreases gradually;the particle dispersion index increases gradually;the fractal dimension of pore and particle decreases gradually.?5?The content of illite is positively correlated with cohesive force c_d,negatively correlated with internal friction?_d,residual cohesive force c_r and residual internal friction?r.The content of the mixed layer is negatively correlated with the cohesive force c_d,positively correlated with the internal friction?_d,the residual cohesive force cr and the residual internal friction?r,and positively correlated with the residual cohesive force cr and the residual internal friction?r.The residual cohesion cr and residual internal friction?r of pore fractal dimension are negatively correlated,while the average diameter and dispersion index of particles are negatively correlated with residual cohesion cr and residual internal friction?r.There is no obvious linear relationship between particle shape ratio and residual strength parameters.The fractal dimension of pore,residual cohesion cr and residual internal friction?r are negatively correlated.