Formation Mechanism And Mechanical Characteristics Of Soft Rock Composite Slope In Surface Coal Mine And Mining Control Technology

This paper conducts a research on the Formation mechanism and mechanicalcharacteristics of soft rock composite slope in surface coal mine and mining controltechnology. The importance is acknowledged that the ground stress and displacementwhich is cause by mining engineering is critical for the safety of a open-pit mine. Thedatabase of engineering geology classification for large-scale open-pit mines in Chinais established through statistical analysis, as the open-pit mines in China are classifiedgrounded on the geological conditions.The formula for excavation volume is deduced by the excavation-Heaping basicengineering steps, which further acts as the basis of the calculation formula of heightof dump. Combined with the basic parameters in Shengli Open-pit Mine and thedumping method, the curve of height of outer dump is obtained. According to theweak layer’s failure model and rheological properties, the calculation method isdetermined for the slope failure. Finite element analysis and numerical simulationsoftware are adopted to analyze the slope stability of weak layer, and it reveals thechanging law for soft slope stability during development.Heaping operation resulted in the compressed cement of bulk material by the roleof gravity, which enhances the density of bulk material. The shear strength increasesin a linear fashion by the compressed stress and the cohesion enhances in a quadraticfashion. Repeated Heaping brings about the long-term shear stress on the weak layer.The mechanical parameters of rock applied with a full stack pressure and compressionset was in a negative growth over time diminishing exponentially. Heaping work isbeneficial to the shear strength of the bulk material while detrimental to the base rock.The stress, which derives from repeated excavation and heaping in weak layers,brings about the unbalanced stress unloading in gob area and the base, which couldfurther result in the stress localization in the slope toe and the shaping of stress arch.The unbalanced stress resulting from heaping work promotes the development ofdeformation in weak layer. According to the rheological properties of weak layer, thedisplacement formula under piling load is obtained, by means of numerical simulation,as the stress-strain characteristics in weak layers is revealed.The comprehensive analysis of geological and hydrological conditions have beenconducted in the south slope in Shengli Open-pit Mine, and the distribution andcharacteristic of weak layers have also been outlined. The factor of safety for south slope is calculated with suitable section and lithological parameters. The miningschedule is designed according to the result, which will be beneficial to the recycle ofresource in weak layers.