Experimental Study on the Blast Damage Law of the Simulated Coal

In order to further study the coal blasting mechanism and improve the gas drainage effect in coal mine,we analyzed the process of coal blasting damage and fracture and divided it into the initial stage of blast waves and the later stage of the detonation gas and coal mine gas,then we selected the damage and fracture criterion.Based on the similarity theory,we designed coal blast experiment and measured ultrasonic wave velocity and blast strain waves.The results show that the coal blast damage is the result of the interaction of blast shock wave,blast stress wave,and detonation gas and coal mine gas.The coal mine gas has a positive role in the coal blast damage.Near the blasting area,the blast wave is the main reason of blast damage,which makes the blast damage decrease rapidly.However,in the area at a moderate or long distance from the blast point,the main reason of blast damage is detonation gas and coal mine gas,the blast damage decreases slowly,and the damage can last a long time at a high level,The damage range and degree of the blast are greater than general rock.