Research On Engineering Geological Characteristics And Slope Stability Of Red Beds In Southern Anhui Province

Red Beds,as a kind of special Rock-Soil,the water is easy to collapse,to properties of softening,and are widely exposed in southern Anhui Province region,the research of the engineering geological properties of the Red Beds under different buried depth and the stability of the Red Beds slope,for engineering construction in the region,especially deep foundation engineering and the highway construction has very important influence.In this paper,based on geological survey center of China geological survey Nanjing "urban geological survey project" project,through the indoor experiment and numerical simulation,the method of combining the conducted under different buried depth,the composition,microstructure characteristics,physical and mechanical properties,water rational qualitative research,at the same time,through numerical simulation,The stability of Red Beds cutting slope under different rainfall intensities is calculated,and the instability mechanism of slope is analyzed in combination with the difference of engineering properties under different buried depths of Red Beds.Finally,a reasonable reinforcement scheme is determined.The results show that:(1)The Qiyunshan Formation is purplish red argillaceous cementation silty feldspar lithic sandstone(siltstone),and the sedimentary environment is fluvial facies sedimentary environment.The Huizhou Formation is purplish red iron cementation silty feldspar sandstone(iron siltstone).The sedimentary environment is turbidity current sedimentary environment.With the increase of burial depth,the content,density,specific gravity and uniaxial compressive strength of feldspar minerals in the two formations of samples increased,while the content of clay minerals,natural water content,saturated water absorption and porosity decreased.(2)The disintegration of the Red Beds in southern Anhui Province is from the outside to the inside,the cracks gradually expand from the end to the center,the particle size of the residual disintegration gradually decreases,and the disintegration is accompanied by the process of falling argillaceous disintegration.With the increase of burial depth,the disintegration degree of the two formations of rocks decreases,and the overall disintegration degree of Huizhou Formation is relatively low.The softening coefficient showed a linear increasing trend,and all of them belonged to the softening rock.The index of collapse resistance was higher in Huizhou Formation.The two formations of samples are classified according to their durability and belong to medium-high durability rocks.(3)Rainfall mainly affects the whole weathered layer of the Red Beds slope,but has little effect on the strong weathered and middle weathered layer.The safety factor is reduced to some extent by moderate rain and heavy rain,but it is not unstable.The heavy rainstorm greatly reduced the safety factor and caused instability of the slope.Rainfall,excavation and weathering are the causes of the slope instability,and the lithology,slope structure and hydrological properties are the determinant factors of the slope instability.Combined with the characteristics of the slope,the anchor and shotcrete retaining wall is chosen as the reinforcement scheme of the Red Beds cutting slope in southern Anhui Province.