Research On Key Parameters And Ground Pressure Behavior Law Of Roof Cutting And Entry Retention In Zhuzhuang Coal Mine

As a pillar free mining technology,roof cutting and roadway retention are widely used in various major coal mines,alleviating resource waste and reducing working face preparation time,which is a major contributor to green mining in China’s coal mines.Based on the background of Working Face III635 in Zhuzhuang Coal Mine,the thesis carries out a study on key parameters of roof cutting and retention under hard roof and rock pressure manifestation by using a combination of theoretical analysis,numerical simulation and field test,and the best roof cutting height,roof cutting angle and blast hole spacing were proposed for advance presplitting roof cutting and pressure relief in roadway III635.At the same time,the analysis on the control effect of surrounding rock along the goaf retention roadway and rock pressure observation were carried out.The main research content are as follows:(1)By establishing a mechanical model,calculating the periodic collapse step distance,and determining the optimal top cutting height and top cutting angle of the III635 working face,on this basis,changing the load on the underlying rock layer borne by the basic roof,studying the impact of top cutting height and angle on the maximum tensile stress of the uncapped part.(2)In accordance with the actual geological conditions,a Numerical Model is constructed to study the effect of roof cutting height and angle on the collapse of the roof plate,the surrounding rock deformation and vertical stress in III635 machine lane.The optimum cutting height and angle are determined.The stress transfer between roadway and goaf roof is effectively cut off.The roof cutting part can collapse along the cutting surface,and the uncut part breaks under the action of mine pressure.Weakening the pressure behavior of roadway along goaf(3)Based on the explosive and rock parameters,a double hole blasting model is established,and the crack propagation and effective stress variation rules under double hole blasting are analyzed.Effects of varying the blast hole spacing on crack expansion and effective stress were investigated and the optimum crack penetration was determined for blast holes spacing of 800 mm.The thesis has 63 figures,10 tables,and 80 references.