Study On Slope Stability Of Drainage Fields In Abandoned Mine Pits After Filling With Water

Based on the project of "Comprehensive Prevention and Control of Geological Disasters in Fushun West Open Pit Mine",the slope of the internal drainage field of Fushun West Open Pit Mine was selected as the research object,and the slope stability coefficients before and after water filling were calculated by using the data of field survey;the slope change pattern under different water depth conditions was observed by using model test;the change pattern of slope seepage field,stress field and displacement field under different water depth conditions was simulated by using the continuous medium method;and the following research results and conclusions were obtained by combining the water filling engineering simulation of two typical profiles in the north and south of Fushun West Open Pit Mine:(1)On the basis of the Moore-Coulomb criterion,the formula for calculating the stability coefficient of the slope before filling with water is derived by using the total stress method,and the results show that the stability coefficient of the slope before filling with water decreases with the increase of the slope;the formula for calculating the stability of the slope after filling with water is derived by using the effective stress method,combined with the weakening parameters of the slope soil after encountering water and the simplified pore water pressure of the seepage field.The results show that the stability of the slope decreases as the water-filled height increases.Constructing the stress-strain intrinsic structure relationship,it was concluded that the displacement of the slope surface of the inner drainage field is greater as the height of water filling increases.(2)Geotechnical experiments were used to test the physical and mechanical properties of the slope of the internal drainage field,to determine the physical and mechanical parameters of the geotechnical body of the slope of the internal drainage field,and to provide data support for the numerical simulation of the slope of the internal drainage field.The similar model test method was used to observe the changes of infiltration line,soil pressure,pore pressure and displacement of the internal drainage soil slope with different slope forms under the action of water filling,and to analyse the slip deformation law of the internal drainage soil slope under different slope angle and slope height conditions.The results show that with the increase of slope angle and height,the soil pressure,pore water pressure and displacement keep increasing and the stability of the slope decreases.(3)Using Fl AC 3D,the changes of seepage field,stress field and displacement field after filling with water under different slope shapes were analysed,and the obtained change laws were consistent with the experimental results,dividing the slip process into three stages.Surface softening and deformation stage: At the early stage of water filling,water is mainly infiltrated,the water content of the slope soil increases,the slope surface is gradually saturated,the soil softens and the shear strength decreases,but no obvious collapse occurs.Deep slow change phase: As water filling proceeds,further infiltration of water within the slope,scouring and accumulation of the slope increases,forming obvious depressions and collapse areas,while the slope surface sinks and accumulates at the foot of the slope due to creep of the soil body.Overall slip damage stage: In the process of water filling,with the increase of water filling height,the slope appears to collapse on a large scale,water flows in the direction of collapse,the overall deformation accumulates to a certain extent,the slope appears to tension fracture,water continuously penetrates and the slope deformation is significant.The cracks on the slope continued to expand downwards,causing slippage on the inner side of the slope,resulting in the instability of the slope.(4)The current situation of the Nanbang dumping site in Fushun West Open-pit Mine,-90 level,-40 level,0 level,+40 level and +70 level were numerically simulated.The results show that before water filling,the negative feedback state of compaction of the slope of the inner dump yard in the direction of gravity will increase the displacement of the slope of the internal dumping site,especially the upper part of the slope of the internal dumping site.After water filling,the slope of the internal dump will continue to be squeezed vertically downward,and the water will weaken the soil mechanical parameters of the slope,thereby increasing the displacement of the slope.The maximum variation area of slope displacement in the inner dumping site increased with the rise of the water level,and with the increase of water filling depth,the slope displacement increased,and the stability of the slope in the internal dumping site decreased.The thesis has 65 figures,23 tables and 90 references.