Analysis Of Slope Stability Of Nan-fen Open Pit Mine Under Blasting Vibration

Taking Nanfeng iron mine as engineering background,aiming at the stability of open pit slope under blasting vibration,combining the criterion of slope determination,strength reduction of slope stability analysis and theory of blasting vibration calculation,the stability state of slope under static load and blasting vibration load is analyzed.In order to analyze the influence of blasting vibration influence factors on open-pit slope,the sensitivity of influencing factors of slope stability under blasting vibration is determined by the coupling analysis method of multiple factor orthogonal experimental grey relation theory and single factor analysis method.In order to reduce the influence of blasting vibration on the slope,combined with the sensitivity analysis of influencing factors and the actual mining situation of Nanfeng iron mine,the corresponding active control measures of slope stability are put forward to ensure the safety and stability of open-pit mining.The main research contents are as follows:(1)Considering the influence of blasting vibration on the stability of Open-pit slope,the safety factor of slope is 1.26 under static load,and the safety factor of slope is reduced to 1.14 under the action of dynamic load.The peak acceleration of horizontal direction is greater than that in other directions,and the peak value of acceleration from foot to slope decreases.With the increase of detonation distance,the reduction of safety factor caused by blasting vibration is decreasing,and the coefficient of safety factor is reduced by 9.1%.When the detonation distance is definite,the safety factor decrease rate is increasing with the increase of the single sound dose and the reduction of safety factor is 11.3%.(2)According to the influence factors of slope stability under blasting vibration,the coupling analysis method and single factor analysis method are used to determine the sensitivity order of each influencing factor: Single explosive charge>total quantity of explosive>detonation distance>duration of vibration>hole rows>hole number.The number of gun holes and the number of holes in the single ring of explosive charge are negatively correlated,indicating that the safety coefficient decreases with the increase of the variable;The duration of detonation and vibration is positively correlated with the influencing factors,indicating that the safety coefficient increases with the increase of the variable.(3)According to the sensitivity analysis of influencing factors and the actual mining situation of Nanfeng iron mine,three effective active control measures are proposed: interference reduction method,changing blasting parameters and controlling the range of crushing zone.Among them,the excavation of the surrounding surface and damping trench can effectively obstruct or control the maximum amount of ammunition,damping effect is obvious,each additional temporary surface,vibration damage can reduce 10%~15%.