Study On Optimization Of Roadway Support Scheme In Panel Area Of Shallow Seam With Thin Bedrock

It is not easy to form a structure in the roof after the roadway is excavated in the shallow and thin bedrock coal seam.The collapse of the roadway has a certain suddenness,and the actual support strength is often conservative,It has important theoretical significance and practical value to study the reasonable support method of this kind of roadway.Based on the "beam-block" theory,the mechanical analysis of the roadway roof under different bedrock thickness is carried out:with the increase of bedrock thickness,the main causes of roadway failure change from flexural failure under the guidance of "beam" theory to caving failure under the guidance of "block" theory,from tensile failure to shear failure.Combined with FLAC3D numerical simulation,the complete rock mass height distribution above the roadways with different thickness of bedrock is obtained.The failure modes of roadways with different thickness of bedrock are respectively "flexural failure","overall fall"and" arch fall".Analyze the supporting theory applicable to the roadway in shallow buried thin bedrock coal seam.When the failure form is "flexural failure",the supporting theory based on the beam theory can be used;When the failure mode is "overall fall",the calculation method of surrounding rock pressure can be used for reference in "Terzaghi" theory in support design of shallow roadway.It is found that this type of roadway does need to control its roadway displacement within a small range to ensure safety;When the form of failure is " arch fall ",there is an "inflection point" in the support strength.Finding the "inflection point" of support strength is the key to balance safety and economy.Combined with the specific occurrence conditions of Hongliulin 3-1 coal seam,it is considered that the damage form of 3-1 coal seam roadway is 5m and 15m as the limit,which can be summarized as "whole fall" and "arch fall".The "Terzaghi theory" under "whole fall" is reasonable and available for the design of support parameters.And get the allowable maximum value of the roadway.The inflection point of the supporting strength under " arch fall " is given.The field measurement shows that the roadway has better stability under this supporting strength.This thesis provides theoretical guidance for the roadway support of 3-1 coal seam in hongliulin coal mine,and has certain significance for the improvement of the roadway support technology in shallow and thin bedrock coal seam.