Study on Rayleigh Wave Detection for Distribution of Fractured Zone about Short Distance Anti-Procedure Mining Floor Strata

The damage degree analysis of floor strata is of great importance for the feasibility demonstration of anti-procedure mining and the safe mining. This paper takes Rayleigh wave detection technology to analyze the Fissure developmental condition of floor strata for seam No.3 with short distance anti-procedure mining practice for +570 m No.6 crossheading in Muchengjian mine in Beijing and gets the partition of damage degree and its space distribution of seam No.3 floor caused by the seam No.2 mining. The results indicate that the floor has some stratified interfaces because the seam No.3 floor is in the fractured zone caused by the seam No.2 mining and the layered number of overlying strata beside the boundary is more than the middle of goaf because of the developmental fractured zone of working boundary; The strata above the seam No.2 caving zone can be divided into weak layered zone and strong layered zone and the cracks of rock caused by the seam No.2 mining is developed especially between the position 19m and 7.8m of the seam No.3 floor The medium sandstone stratum of the seam No.3 floor has large thickness, good integrality, few stratification and basic complete state, this section is the key horizon or stability for the No.3 seam. The basic anastomosis between the layered results of Rayleigh wave detection reflects the reliability of Rayleigh wave detection for confirming the developmental condition for strata fissure by anti-procedure mining. The application of Rayleigh wave detection shows that to research the stability of floor strata in the anti-procedure mining process by this detection method, the dilamination is behaved obviously on the detecting curve, the structure damage of strata and the fracture development are easy to recognize; and with the characteristic of high working speed and it is easy to use, On analysis of the results from Rayleigh wave detection, combined with the theory analysis, numerical simulation, floor drilling in the site and so on, the successful anti-procedure mining has already been got in the Muchengjiang mine.