Mechanism and Control Technique of Rib Spalling Disaster in Fully-mechanized Mining with Large Mining Height in Soft Coal Seam Face

Coal wall rib spoiling (CWRS) is one of the most important disasters connected with underground coal mining, because it significantly affects the safety of mining workers and equipments. CWRS occurs more likely in fully-mechanized mining with large mining height (FMMLMH), especially in soft coal seam working face. The key to control CWRS is to reveal its mechanism and obtain the effective control technique of the CWRS. This paper focuses on analysis of CWRS process, measurement of features of CWRS in FMMLMH, and establishment of damage mechanical model of coal wall crack development evaluation system and mechanical model of "rib spoiling body" (RSB) stability on CWRS in FMMLMH face. The results show Mat: CWRS is a stability-lost process of coal wall micro-cracks because of their development, expansion, and connection with each other into RSB. Possibility of the CWRS depends on the degree of coal cracks development in coal wall and the stability of RSB. Geometric feature of RSB in soft coal face in FMMLMH is like a "wedge". The greater the damage of coal wall is or the smaller the stability coefficient of the "wedge" is, the higher the probability of CWRS will be, reversely, the smaller the damage of coal wall is or the larger the stability coefficient of the "wedge" is, the lower the probability of CWRS will be. Based on the above, the prevention and control technique of CWRS should be proposed and it has already been successfully applied in FMMLMH in soft coal seam working face.