Abstract: With application of Rayleigh wave detection technology, field measurement and numerical simulation, the fissure developmental condition of floor strata for seam No.3 with short distance abnormal procedure mining for +450 m in Muchengjian mine is detected, obtaining the partition of damage degree of seam No.3 floor and its space distribution caused by the seam No.2 mining.The research results indicate that the seam No.3 floor ranges in the fractured zone caused by mining of the seam No.2；the cracks of rock caused by the seam No.2 mining is developed well especially between the position 19 m and 7.8 m of the seam No.3 floor；The medium sandstone stratum of the seam No.3 floor is in basic complete state, and this section is the key horizon of stability for the No.3 seam.The basic drilling test coincides with the results of Rayleigh wave detection, reflecting the credibility of Rayleigh wave detection with abnormal procedures to detect the fracture of floor strata.Then the numerical simulation is used to analyze the pressure released effect and regions with abnormal procedure of mining.

Key words: Rayleigh wave detection, Numerical simulation, Fissure distribution, Pressure released effect