TAN Y, WANG Y, LI H, et al. Structural evolution of a quasi-granular arch within a thick loose layer and overburden movement behavior[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(2):43-53.

doi: 10.16186/j.cnki.1673-9787.2024110017

Received:2024/11/08

Revised:2024/12/03

Published:2026/01/28

Structural evolution of a quasi-granular arch within a thick loose layer and overburden movement behavior

Tan Yi1,2,3, Wang Yu1, Li Hui1, Zhang Shaopu1, Feng Yixiang1, Ge Zhibo1, Tang Ze4, Zhang Zhixiang4

1.School of Energy Science and Engineering， Henan Polytechnic University. Jiaozuo  454003， Henan， China；2.Henan Provincial Collaborative Innovation Center for Coal Safety Production， Jiaozuo  454003， Henan， China；3.School of Earth Sciences and Engineering， Hehai University， Nanjing  210098， Jiangsu， China；4.The Fourth Geological Exploration Institute of Henan Geology and Mineral Bureau， Zhengzhou  450007，  Henan， China

Abstract: Objectives To investigate the relationship between the development of a quasi-granular arch structure within a loose layer and surface damage， this study examines the structural evolution of the quasi-granular arch and the overburden movement behavior under a thick loose layer. Methods Taking the 2303 working face of Hemei No.5 Mine as the engineering background， PFC particle flow numerical simulation， on-site drilling leakage observation combined with microseismic exploration， and nonlinear regression analysis were comprehensively employed. Results The results indicate that， with the advance of the working face， the overall failure mode of the bedrock exhibits a positive trapezoidal shape. Particles at the bottom of the loose layer are disturbed by bedrock bending and subsidence， forming an arch-shaped bonded failure zone. During particle movement and compaction， a quasi-granular arch structure with a certain bearing capacity is gradually formed. The fissure field， stress field， and displacement field show distinct stage-dependent evolution characteristics. The development height of the water-conducting fracture zone experiences four stages： rapid growth， slow growth， abrupt increase， and stabilization. The stress field evolution undergoes three stages：  development of the bedrock pressure arch， coupled evolution of the pressure arch and quasi-granular arch， and independent development of the quasi-granular arch. Surface subsidence evolves through four stages： slow subsidence， accelerated subsidence， rapid subsidence， and stabilization， corresponding well to the staged evolution of the three fields. Surface subsidence measurements based on a surface monitoring circle show that the subsidence curve is approximately V-shaped. After mining， step-like cracks appear in the central area of the goaf， while tensile cracks develop on both sides， consistent with field investigation results. Field observations indicate that the height of the water-conducting fracture zone reaches 147.46 m， with a fracture-to-mining ratio of 16.49， while the caving zone height is 57.46 m， with a caving-to-mining ratio of 6.43. Based on regression theory， a multivariate nonlinear prediction model for maximum surface subsidence under thick loose layers is established， effectively reducing prediction errors caused by single-factor consideration and achieving a fitting coefficient of 0.98.  Conclusions The proposed results and methods provide a useful reference for coal mine safety production and surface protection under similar geological conditions.

Key words: thick loose layers; quasi-granular arch; water-conducting fracture zone; overburden failure; surface subsidence