Theory And Its Application Bolt And Cable Anchorage In Mining Roadway With Great Thick Complicated Roof Composed Of Thin-bedded Strata

Such accidents often occur as the deformation, failure, spall-off and roof-fall of the roadway. According to the statistics, the roadway accidents take up more than 59% of the accidents in the mine. The reasons are that the laws of the roadway deformation and failure have not been understood, and the supporting theories are also unperfected so far. It results in that the support designs are engineering analogy methods mostly without scientific guidance, so the roadway's supporting form cannot be chosen reasonably. Therefore, it cannot ensure the stabilization and safe usage of the roadway under different geological conditions.After extensively investigating the form of the coal roadway's deformation failure and the roadway supporting presently, the paper designs the correct material ratio under the similar simulation theory, and processes the great ratio tri-dimension similar simulation experiment under the typical geological condition and different supporting forms. By using advancedtesting apparatus with scientific testing methods, the experiment observes the stress distribution, deformation and displacement, and the entire process of the crack generating, extending, connecting and destroying in the roadway surrounding rock.After analyzing the testing data of the surrounding rock stress distribution, deformation and crack development, laws under different supporting conditions and the influence of dynamic load are found concerning the stress distribution, the displacement between top and bottom, the displacement between two walls of the roadway, and the crack's generating, extending, connecting and destroying in the roadway surrounding rock with the increase of load.The laws are as follows: with the extraction load increasing,1) in naked roadway: the stress distribution of the coal-and-rock block around the roadway is mostly in the state of tension, and the surrounding rock breaks badly. Multi-layers separation cracks appear in the roof with a bigger range of the rock cavity.2) in roof bolting roadway: the stress in the roadway roof and bottom is mostly in the state of compression, but the coal block in the walls remains tension stress, so, the walls destroyed severely. Outside the bolting area, multi-layers separation cracks also appear in the roof(less than naked roadway), and the range of the rock cavity is less than that of the nakedroadway.3) in roof and walls bolting roadway: the roadway surrounding rock is in the compression state basically. The surrounding rock deformation has been controlled to some extent. One separation crack appears outside the bolting area. The range of the rock cavity has been decreased further.4) in roof and walls bolting and roof cable supporting roadway: the roadway surrounding rock is in the compression state basically. The surrounding rock is less destroyed. The separation crack is eliminated in the roof. The displacements of the top-bottom and walls have been controlled effectively.To sum up, the paper puts forward the compressed wall model and four kinds of roadway roof BEAM—ARC structure models under different supporting conditions: the bigger range of multi-layers superposition BEAM—ARC structure model when the roadway is naked; the roof compounded compressed BEAM—ARC structure model when the roadway is supported by roof bolting; the roof compounded compressed BEAM—ARC structure model whose walls are steady when the walls and roof are supported by bolting; the compound compressed BEAM structure model which is hanged by cables after the surrounding rock is reinforced by cables.By using the numerical analysis method, the complement and expansion of the similar simulation, the paper simulates four roadways, which includetwo roof types and two supporting conditions (naked and bolting).From the numerical simulation results, the laws of the stress, displacement and plastic region are found to prove that the roadway surrounding rock has the BEAM—ARC destroyed characters.According to the conclusion of the similar simulation experiment and numerical analysis, the mechanics models have been built up which include two types of walls (steady and unsteady) and different supporting conditions. The paper has researched the deformation and destroyed characters of each mechanics model. Based on the above, the new method of roadway supporting has been put forward.According to the conclusion through theory analysis and simulation experiment, a supporting scheme of one mechanized mining starting cut has been designed, which is located at Laoshidan Mine in Haibowan Mine Company of SHENHUA GROUP. The scheme has been applied actually and has achieved better effect.