Quantitative evaluation method and classification support technology for surrounding rock of coal seam tunnels

JIAO Jiankang; SUN Zhiyong; WANG Tao; FU Yukai

doi:10.16186/j.cnki.1673-9787.2023080003

Abstract：Objectives In order to establish evaluation indicators and quantitative classification methods for the stability of coal roadway surrounding rocks in the Jincheng mining area,Methods on the basis of statis-tical analysis of 68 sets of coal roadway surrounding rock strength,rock structure development degree,and geostress data in Jincheng mining area,the influencing factors of coal roadway surrounding rock stability were comprehensively analyzed.Five key influencing indicators were selected,including maximum horizontal principal stress,vertical principal stress,comprehensive strength of the roof,average strength of the roadway coal body,and thickness of the fractured rock layer within a 10 m range of the roof.Three comprehensive in-dicators,namely roof stress intensity coefficient,roadway stress intensity coefficient,and roof looseness coef-ficient,were proposed.Through K-means clustering algorithm,the roof and roadway stability of the roadway were quantitatively classified.Combined with the roadway formation method and coal pillar size,the coal roadway surrounding rock in the Jincheng mining area was divided into 5 stability categories and 30 types of surrounding rock.Specific support forms and parameters were proposed for different types of tunnel sur-rounding rock stability categories,and precise matching was carried out for different types of surrounding rock anchoring methods,composite components,and protective surface components.Finally,the rationality of the classification method and support scheme was verified through on-site industrial practice.Results The monitoring results of mine pressure indicated that the maximum displacement of the roof and floor during tunnel excavation was 78 mm,and the maximum displacement of the two sides was 58 mm.During mining,the maximum displacement of the roof and floor during tunnel excavation was 260 mm,and the maximum dis-placement of the two sides was 119 mm.Conclusions The evaluation indicators and quantitative classifica-tion methods for the stability of surrounding rock in coal tunnels in the Jincheng mining area were practical and feasible,and the classification support scheme was reasonable.