Control factors andinfluencing patterns of surface subsidence in deep high-concentration cemented backfill mining

YANG Baogui; GU Chengjin; SHI Zhan; YANG Faguang; WANG Longfei; LI Hongjiao

Abstract：Deep mining has become a key challenge for China's coal industry,especially under the constraints of high stress,high temperature and high permeability,it is urgent to seek effective mining technology.Filling mining technolo-gy,especially the high-concentration cemented backfill technology using coal gangue as a filling material,has been gradually applied to deep mining and has become an effective means to cope with this challenge.Based on the ex-isting literature,the filling process,influencing factors and control effects of five backfill mining methodswere analyzed.Three types of factors affecting the surface subsidence control effect of deep high-concentration cemented backfill min-ing were summarized:geological mining conditions,filling technical conditions and backfill properties.To further under-stand the uniqueness of deep high-concentration cemented backfill mining,the mechanical interaction model between high-concentration cemented backfill and roof was constructed,and the overburden movement characteristics of high-concentration cemented backfill mining stope with deep long wall were deeply analyzed,and the discrimi-nant conditions for rock stability was clarified.Based on the FLAC numerical simulation results,the main factors affect-ing the control effect of surface subsidence and their order of importance were determined:working face width>filling rate>backfill strength>coal seam thickness.In addition,it was found that the influence of coal seam thickness and working face width on the subsidence effect is negatively correlated,while the influence of filling rate and backfill strength is positively correlated.Finally,combined with the actual data of a mine test mining area,the optimal working face width(100 m),filling rate(90％)and backfill strength(3 MPa)are determined,and the surface subsid-ence data(4-15 mm)are in good agreement with the numerical simulation results through comparative analysis.This research provides a theoretical basis and technical support for surface subsidence in deep mining areas control.