Research on in-situ protection technology of pressurized limestone water in the coal seam floor of North China-type coalfield from the perspective of resilience

GAO Baobin; REN Chuangnan; LI Bingbing; CHENG Lei; SONG Shaopeng; QI Zhihu; XU Ying

doi:10.16186/j.cnki.1673-9787.2023050022

Abstract：Objectives To promote the high-quality development of water-preserved mining technology and ef-fectively solve the problem of in-situ protection of pressurized limestone water in coal seam floor of the North China-type coalfield,Methods the whole process of resistance,recovery and re-adaptation of the coal seam floor under the influence of mining and pressurized water was analyzed from the three attributes of re-silience(resistance,recovery,and adaptability).According to the characteristics of system resilience evolu-tion under disturbance,a technical framework for in-situ protection of pressurized limestone water in the coal seam floor of North China-type coalfields was proposed,with an emphasis on precision,efficiency,and comprehensiveness.This framework focused on the precise determination of the target area,efficient grouting of multi-branch wells,and comprehensive evaluation of water-preservation effects.Results The results showed that the precise determination of the management target area included two aspects:vertical layer de-termination and lateral target determination.The efficient grouting of multi-branch wells included three steps:setting,drilling and injection.The comprehensive evaluation of the water conservation effect included two aspects:evaluation of the grouting effect on the coal seam floor rock layer and evaluation of the restora-tion of water resources'carrying capacity.The vertical layer position of coal seam floor grouting was deter-mined based on the calculation of the damage depth of the floor and the thickness of the critical water bar-rier layer.The lateral target position of floor grouting was determined based on the detection of key index pa-rameters and the calculation model of the vulnerability index,forming a quantitative determination method and software system for the target area of floor grouting.Multi-branch well grouting combined with direc-tional drilling technology was used to grout and seal relevant fissures,reducing the number of straight well sections and improving drilling efficiency.In terms of"safe mining"and"water resource protection"con-cepts in water-preserved mining,an in-situ water conservation effect evaluation method was proposed based on the detection of the grouting effect of the floor rock layer and monitoring the restoration of the water re-source carrying capacity.Conclusions The project had been applied in a mine in Anhui Province,ensuring the safety of coal seams mined on pressurized limestone water while balancing economic benefits and eco-logical environment development in the mining area.The research results had improved the technical system of water-preserved mining on pressurized water and provided references for subsequent research and field applications.