Influence law of roof breaking structure of working face on roadway pressure in Xiaojihan Coal Mine

Under the conditions of brittle coal and thick main roof,there are a large deformation of roadway and failure of support structure during secondary mining at western mining area in China. Using the method of theoretical analysis and field measurement,the breaking structure of main roof on roadway top and the law of roadway deformation were studied. Taking the key lateral breaking block of main roof as a research target,the second time stress distribution of the roadway surrounding rock caused by the double arch structure of the secondary mining which is brought by the cantilever beam structure double arch structure of the first mining was analyzed in detail. The quantitative relationship between main roof breaking length and coal seam thickness,strata characteristics,overlying load,coal pillar parameters and the stress concentration was given. The expressions of coal pillar top load under different breaking structures were obtained. Results show that the “ double arch” hinged structure formed by the breaking of main in the front of the working face is the main reason that causes the severe pressure of this kind of roadway. The irrational coal pillar width will induce the stress function that leading to the overall deformation of the roadway and the failure of supporting struc- ture. The results of the study have a good guiding significance for the surrounding rock control and the reasonable coal pillar size design in a similar engineering geological condition.