TAN Y, WANG Y, LI H, et al. Structural evolution of a “bulk-like arch” within a thick loose layer and overburden transportation law［J］.Journal of Henan Polytechnic University（Natural Science），doi: 10.16186/j.cnki.1673-9787.2024110017

doi:10.16186/j.cnki.1673-9787.2024110017

Received：2024-11-08

Revised：2024-12-03

Online：2024-12-03

Structural evolution of a “bulk-like arch” within a thick loose layer and
overburden transportation law

TAN Yi^1,2,3, WANG Yu¹,LI Hui¹,ZHAGN Shaopu¹, FENG Yixiang¹,GE Zhibo1,
 TANG Ze²,ZHANG Zhixiang⁴

(1.School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China；2.Henan Provincial Collaborative Innovation Center for Coal Safety Production,Jiaozuo 454000,China;3.School of Earth Sciences and Engineer-ing,Hehai University,Nanjing 210098,China;4. Fourth Geological and Mineral Survey Institute of Henan Provincial Geological and Mineral Exploration and Development Bu-reau,Zhengzhou 450007,China.)

Abstract: [Objective] In order to study the evolution law and inner connection of fissure field, stress field and displacement field of overburden rock mining under thick loose layer. [Methods] Taking the 2303 working face of Hemei Minmetals as the research background, this study comprehensively applies PFC particle flow numerical simulation, on-site drilling leakage observation combined with micro motion exploration measurement, and nonlinear regression analysis to investigate the evolution of the "quasi loose arch" structure and the migration law of overlying strata in thick loose layers. [Results] The results show that with the pushing and mining of the working face, the overall failure mode of the bedrock is in a "positive trapezoid" shape. The particles at the bottom of the loose layer are disturbed by the bending and sinking of the bedrock, forming an "arch shaped" bonding failure zone. During the movement and compaction process, the particles form a "quasi loose arch" structure with certain bearing capacity. The fissure field, stress field, and displacement field all have stage development characteristics. The height development of the water conducting fissure zone goes through four stages: rapid growth, slow increase, sudden increase, and stability. The evolution of the stress field mainly goes through three stages: the development of the "pressure arch" structure of the bedrock, the joint evolution of the "pressure arch" and "quasi loose arch" structures, and the development of the "quasi loose arch" structure. The surface subsidence mainly goes through four stages: slow subsidence, rapid subsidence, rapid subsidence, and stable subsidence. The evolution stages of the "three fields" correspond to each other. By constructing a measurement circle on the surface to measure the surface subsidence value during the process of push mining, the results show that the overall surface subsidence curve is approximately V-shaped. After the push mining is completed, step cracks appear on the surface in the middle of the goaf, and tensile cracks appear on both sides of the goaf, which is consistent with the actual exploration results. The on-site joint drilling leakage observation and micro motion exploration measurement results show that the height of the water conducting fracture zone in the 2303 working face is 147.46m, and the fracture production ratio is 16.49; The height of the collapse zone is 57.46m, and the collapse mining ratio is 6.43. A multivariate nonlinear prediction formula for the maximum subsidence value of thick and loose layers was constructed based on regression theory, effectively reducing the prediction error of the maximum subsidence value considering a single influencing factor, and achieving the best fitting goodness of 0.98. [Conclusion] The research results and methods can provide reference for the safety production and surface protection of coal mines under similar conditions.

Key words: thick loose layers ; loose bulk arch structure; hydraulic fracture zones ; overburden damage ; surface subsidence

CLC: