| Based on the mining process of 2-2# coal seam, interval type group coal seam spacing lithology, landform characteristic parameters and other factors of Nanliang coal mine, the roof movement law of lower group coal are studied. The methods of field investigation, laboratory experiments, theoretical calculation, numerical simulation and field measurement are used to structured and systematic analysis of the law of the concentrated stress transfer under interval coal pillar and the movement of the roof under the coal pillar and gob reasonable support resistance, breaking mode and rules of basic roof, the main research results are as follows:(1) Based on the geomorphic features of Nanliang coal mine, the ground surface is divided into gentle landform and gully landform, and the distribution law of coal pillar overburden under two kinds of geomorphology is analyzed respectively. The calculating method of the overburden load distribution of coal pillar is obtained by numerical simulation and theoretical calculation. The calculation method of the overburden load distribution of the gentle landform pillar and calculation method of the overburden load distribution of the gully landform pillar have been list in the text.The linear load inclination is consistent with that of the gully.(2) We established the numerical simulation of gentle and gully topography and got the regular of the stress concentration in coal pillar. At the same time, we analyzed the quantity of the coal pillar's effect to the vertical stress and the range of horizontal stress to the coal pillar floor. The result shows that the biggest influence depth of the interval type coal pillar is bigger than the layer spacing in the 2-2# coal, which means that the vertical stress forms stress concentration in the main roof of the lower coal group, and it affects the law of motion in the 3-1# coal while the levels of stress concentration has no effect to the law of motion of the lower coal group.(3) We established the gently, gully combination model with numerical simulation software FLAC, the 3-1 # coal seam roof load curve was obtained. With the diversity of rectangular elastic thin plate model boundary conditions, we selected the four edges clamped and the trilateral clamped and simply supported. Finally, we got the regular of the stress distribution and the deflection of roof in the 3-1# coal under the condition of gully and under the flat landscape.(4) Energy method based on the theory of energy release plate crack judgment criteria, we plugged the regular of the stress distribution of the plate in the guidelines, and explained the roof fracture evolution under the goaf area. Meanwhile, it is concluded that the way of entering and leaving the gully and the depth of gully are the important factors influencing the expansion of dangerous area.(5) Combining the ratio of orthogonal experiment in the laboratory and rock properties laid of Nanliang coal mine, we laid a analog simulation model to research the gully development landscape strata movement characteristics under a shallow and interval of mined-out area. Combining with the numerical simulation, the similar simulation experiment and under the condition of shallow buried coal seam massive roof method to determine reasonable hydraulic support working resistance of 3-1# coal seam is 8605 KN. Taking 20304 working face of Nanliang coal mine as the research object, compared to flat topography and gully topography rule of mine pressure appear, draw a conclusion that periodic weighting interval, biggest support working resistance and dynamic load coefficients of gully topography were larger than flat topography, taking the 30107 working face below the interval mined-out area as an example to analyze the underground pressure law of the fully mechanized coal mining face under the interval coal pillar, the average pressure step interval of the interval coal pillar working face is 11.43 m, The lower cycle to the pressure interval than the interval below the mined-out area. |
PDF Full Text Request