Study On The Influence Of Blasting Vibration On The Gob And Surface Residual Deformation In No.2 Yungaishan Coal Mine

With the continuous mining of coal and the increase of the old goaf year by year,building land is becoming more and more tense,which leads to rebuild the houses above the old goaf.When the old goaf is subjected to dynamic disturbance,it may cause the activation of the old goaf,and then affect the residual movement and deformation of the ground surface and the stability of the rebuilt houses.Surface residual movement and deformation change with time,therefore,when studying the effects of blasting vibration on the residual displacement and deformation of the ground surface,the residual movement and deformation of ground surface should be regarded as the result of the interaction of time effect and blasting effect.Because of the great risk of underground blasting activity,it is impossible to obtain the data of explosion stress wave produced by underground blasting.Therefore,the numerical simulation method is adopted to simulate the characteristics of blasting stress wave.The effect of blasting on the activation of the old goaf and the movement and deformation of the ground surface are analyzed;Using empirical formula,the predicted parameters of surface residual movement and deformation produced by time effect are calculated;The cumulative effect of combination of blasting effect and time effect is expected to adjust the parameters,finally the residual surface movement and deformation changes are predicted and compared before and after the adjustment of parameters of surface residual movement and deformation by using probability integral method.The results show that the maximum vibration velocity of blasting stress is 515cm/s,the main frequency is 30 Hz,and the duration of explosion is 0.1s;The blasting activity changed the basin distribution of the surface residual movement,The area near the source of blasting and from the blasting source 216 m is greatly affected by the blasting activity,which the estimated parameters need to be adjusted.While the range of the area is beyond 216 m,which is less affected by blasting activity,the effects of blasting activities are not considered;Finally,according to the expected results,some suggestions are given for the redevelopment of houses above the old goaf where the blasting activity exists.