Comparison Study On The Ground Pressure Characteristics Of Large Height And Top-caving Mining Face

As the large mining height technology has the advantage of simple miningtechnology, high recovery rate, low technical difficulties in gas management, etc., whichhas become an important way to build high yield and efficiency coal in Shanxi,Neimeng mining area of China. With the large mining height tend to mature, many coaltransforming into fully mechanized coal mining with high cutting height from top coalcaving energetically. However, the considerably differences occurred as the groundpressure behavior of mining face, the distribution regularity of face abutment pressure,roof strata structure, support resistance on coal mining face, cet., which seriouslyrestricted development and popularity of the large mining height.Against the above situation, in this paper, No.1304top coal caving face in Zhaozhuang coal mine and No.4301large mining height in Si he coal mine are selected ascontrastive analysis, according to the mining of seam3#in Jincheng mining area.According to the basis of the key stratum theory proposed by academician QianMing-gao, the ground pressure behavior and stope control was studied comprehensivesystematically by on-site measurement, similar test and numerical simulation, ect.Measures are offered by transforming course, which become top coal caving to largemining height with the seam3#in Jincheng mining area, such as roadway layout,support selection, coal pillar design, roadway support, roof control, ect. Therefore, thestudy has important engineering instructive significance.The result shows that, the big structure of overlying strata in large mining height issimilar with the top coal caving’s, according to the same geological condition. However,the main reason is that the obvious difference of ground pressure behavior is caused bythe difference of small structure. the thickness of immediate roof increased with theincreasing of mining height in similar geological condition, the thickness of caving zonein large mining height is5m more than those in top coal caving, and the thickness offault zone is20m more than those in top caving. The support resistance of top coalcaving is far less than large mining height’s, because of the effect of top-coal, therefore,the theory calculation shows that the support selection should satisfy the request for theweight of overlying strata with8times mining thickness, while the weight of overlying strata with4~5times mining thickness in top coal caving. There is simple miningtechnology, fast advancing speed in large mining height, and the periodical weightingstep distances is obvious less than those in top coal caving, the peak of advancedabutment is near to coal wall in contrast with top coal caving, and lateral abutment is isfar more than coal. In contrast with the top coal caving, the ground pressure behavior oflarge mining height present obvious hysteresis and regional characteristic. The fieldtesting indicates that the delayed distance of ground pressure behavior in large miningheight is about50~300m, which is far more than top coal caving’s50~80m. In twomining conditions, the form of rib spalling and roof fall of coal face exist difference,however, the core content of roof management remain improving setting load of support,moving support in time, accelerating mining rate. In contrast with top coal caving, thesurface movement is far intensive, and presenting obvious hysteresis and regionalcharacteristic in large mining height.