Because of higher space of mined out area in large mining height stope, and direct roof cannot completely fill the space of mined area, hence, there is a larger space need main roof rotary deformation, violent strata pressure behavior and catastrophic accidents easily occurred. In this paper, the law of breaking about overlying strata and disaster characteristics of before and after main roof breaking by acoustic emission, which could be studied during the large mining height stope mining through imitation test with similar materials. The results showed that strata pressure behavior initial mining stage more violent than normal mining stage, main roof was broken after hydraulic support was moved when the main roof reached the maximum span, so the hydraulic support must be sliding advance of support during periodic weighting. The lead abutment pressure peak was located in front of the 5–10 m range of working face, the influence range of lead abutment pressure was located in front of 95–100 min working face, the stress concentration coefficient was between 1.35 and 2.12; The first breaking span of main roof was 90 m, the periodic breaking span of main roof was between 10 to 40 m, AE event number reached 1035 per second during the first breaking of main roof, energy rate reached 4962 MV us /s, acoustic emission signal fluctuates frequently during the periodic breaking of main roof, but the small event and low energy efficiency were main.
The high mining height fully mechanized is a new coal mining technology in recent years for large mining (Ju et al. 2011, Wang 2006), and it is applied to mining height of 3.5 m-7 m thick seam mining (Ju & Xu 2013). The high mining height fully mechanized is widely applied because its mining rate is higher than fully mechanized top coal caving mining (Liu et al. 2010). But there are a set of problems of violent strata pressure behavior and coal wall caving and roof fall and poor hydraulic support stability during the mining, because of mining height increases and equipment performance. The fundamental reason is overlying strata movement and breakage essential difference with the ordinary mechanized mining when the mining height is increased. So it is very necessary to study on law of breaking about overlying strata and disaster characteristics of large mining height stope, which effectively control the large mining height of safe and high efficient mining.
