doi:10.16186/j.cnki.1673-9787.2023060054

Received:2023/06/27

Revised:2023/09/22

Published:2024/05/15

Analysis of “trapezoid” fracture parameters and fracture evolution of overburden in shallow coal seam mining

WANG Peng1, LI Rui2,3, CHENG Zhiheng4,5, KONG Dezhong1, CHEN Haoyi6, ZHANG Hongtu7

1.Mining College of Guizhou University，Guiyang  550025，Guizhou，China  2.Shenmu Energy Bureau of Shanxi Province，Shenmu  719300，Shaanxi，China  3.School of Energy and Mining Engineering，China University of Mining and Technology （Beijing），Beijing  100083，China  4.School of Mine Safety，North China Institute of Science and Technology，Beijing  101601，China  5.State Key Laboratory of Water Resource Protection and Utilization in Coal Mining，Beijing  102209，China  6.School of Civil and Resources Engineering，University of Science and Technology Beijing，Beijing  100083，China  7.College of Safety Science and Engineering，Henan Polytechnic University，Jiaozuo  454000，Henan，China

Abstract:  Objectives Objectives In order to explore the correlation mechanism between the “trapezoidal” fracture 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 “asymmetric oblique four-sided” type.    Results The research results show that the overlying strata, affected by the disturbance of coal seam mining, presents a “trapezoidal” shape along the fracture line on both sides.Due to the φ，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 calculations,it is concluded that the caving distribution pattern of overlying rock is studied on the working face of Yayaomao 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 L_φj =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.

Key words:shallow buried coal seam;breaking parameter;numerical simulation;simulation of similarity;field measurement;