Exploration Technology of Coal Floor Mining Damage Depth

For Chaochuan Ⅱ₁ 21090 working face, ultrasonic wave technology is used to explore and analyze the floor mining damage situation, according to the velocity changes with depth, the mining damage depth is determined. The results show that the mining damage depth concentrates in 20.40 m to 23.36 m, and the facture develops from the deep rock to the shallow rock.