浅埋煤层开采覆岩"梯形"破断参数与裂隙演化分析OA北大核心CSTPCD

Objectives Objectives In order to explore the correlation mechanism between the"trapezoidal"frac-ture parameters and fracture evolution law of overburden mining in shallow coal seam,and quantify the distribution characteristics of overburden caving and fracture.Methods Taking Yayaomao Coal Mine as the research object,this paper analyzes the spatial distribution pattern of overlying rock caving and quantitatively characterizes the distribution parameters of the"trapezoid"of overlying rock caving by means of theoretical analysis,physical similarity simulation,numerical simulation,and field measurement.The overlying rock caving presents an"asym-metric oblique four-sided"type.Results The research results show that the overlying strata,affected by the dis-turbance of coal seam mining,presents a"trapezoidal"shape along the fracture line on both sides.Due to the φ and γ difference of fracture angles,the mining fracture of overlying rock presents an"asymmetric oblique four-sided"type fracture development body distribution shape in space.Conclusions Based on theoretical calcula-tions,it is concluded that the caving distribution pattern of overlying rock is studied on the working face of Yay-aomao Mining Industry 30204.It is concluded that the fracture angle at the opening hole on both sides of the caving rock is φ ∈[58.7°,68.7°],and the fracture angle at the shearer head is γ ∈(60.8°,67.8°).The overburden collapse length was further calculated based on the angle of rupture equation Lφj=11.5 m,Lγj=10.4 m.According to the on-site measurement,30204 working face 3-1 coal seam roof collapse monitoring data concluded that the best height of the overlying rock collapse in 11～30 m,and the best width of the fissure development is within 5 m from the working face cutting eye and coal mining machine head.