Overburden Fracture Characteristics And Roof Control Of Shallow And Special Thick Seam Mining In Gully Region

Based on typical production technology condition of full-mechanized caving mining face of shallow and special thick seam in gully region in Chuancao Gedan Coal Mine,theoretical analysis,numerical calculation and field measurement were adopted to study geology occurrence conditions and mining pressure characteristics of shallow and special thick seam mining in gully region.As well as other key theoretical and technical problems,such as strata stress field distribution,strata rupture and instability,mechanism of dynamic load pressure,and roof control technology of shallow and special thick seam mining in gully region.The results of the study reveal the mechanism of dynamic load bearing pressure of shallow coal seam mining in gully region,which could reduce the damage caused by dynamic load pressure and lay the theoretical foundation for reasonable and effective roof supporting.It has an important reference and guiding significance to safety mining in the similar geological condition of shallow and special thick seam mining face.According to geological occurrence characteristics,surface topography and production technology conditions of shallow and special thick seam in gully region in Chuancao Gedan Coal Mine,The relative relationship between the direction of the face and the distribution of the surface gully is classified.The characteristics of the strata behavior of the working face and the bearing characteristics of the hydraulic support are analyzed,and the statistical analysis is made on the situation of the dynamic load.Based on the combination of three-dimensional geological modeling and numerical calculation,the dynamic distribution characteristics of overburden stress and the dynamic distribution of plastic failure zone in the gully area of shallow coal seam were studied respectively under different occurrence conditions.The dynamic change of surface displacement and subsidence and its influence range,as well as the overburden movement and overlying rock subsidence range were also analyzed.Numerical simulations was used to study rock stress field distribution and of shallow and special thick seam mining in gully region based on the conditions of gully terrain in the Chuancao Gedan Mine.The effect of gully terrain on the stress field of overlying strata of the entire field can be characterized as a significantly affected area,moderately affected area,or non-affected area.Workface 6106 in the Chuancao Gedan Mine had a coal bed depth < 80 m and was located in what was identified as a significantly affected area.Hence,mining may cause sliding of gully slop and increased loading(including significant dynamic loading)on the roof strata.Based on the theoretical analysis,the bearing characteristics,fracture step and influencing factors of the overlying strata were studied.The movement law of overlying strata and the breaking structure of overburden of shallow and special thick seam mining in gully region were studied.Structural characteristics of the overburden,support-surrounding rock relationship,and the mechanism of the dynamic strata pressure of shallow and special thick seam mining in gully region were studied.Reasonable supporting resistance and roof control technology of shallow and special thick seam mining in gully region wree determined.The effect of roof support is analyzed and evaluated according to the characteristics of mine pressure in the field test of mining face 6104.The abutment pressure distribution in the shallow coal seam of the gully area was studied.The stress distribution and stability of the coal pillar under this condition were analyzed,and the reasonable width of the coal pillar was proposed to ensure the safe production of mining face and improve the recovery rate of coal resources.