ZHANG Y, ZHOU Y S, WANG F T,et al.Backfilling mining technology and rational process design for coal seams beneath urban buildings[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(2):22-30.

doi:10.16186/j.cnki.1673-9787.2025080034

Received:2025/08/19

Revised:2025/12/16

Published:2026/01/28

Backfilling mining technology and rational process design for coal seams beneath urban buildings

Zhang Yang1,2, Zhou Yushun1,3, Wang Fangtian1,3, Lu Yan1,3, Hao Wenhua1,3, Wang Xu1,3

1.School of Mines， China University of Mining & Technology， Xuzhou  221116， Jiangsu， China；2.Henan Zhenglong Coal Industry Co.， Ltd.， Yongcheng  476600， Henan， China；3.State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources， China University of Mining & Technology， Xuzhou  221116， Jiangsu， China

Abstract: Objectives To address the challenge of large amounts of coal resources constrained beneath urban buildings， which restrict the sustainable development of coal mines， Chengjiao Coal Mine was selected as a test site to investigate rational backfilling mining technologies and process designs for coal seams beneath urban buildings.  Methods Using engineering analogy， scheme comparison， and theoretical calculation methods， and based on the principle that backfilling mining beneath buildings must prevent surface subsidence， four mining schemes were proposed： fully mechanized mining with cemented paste backfilling， new solid backfilling mining， super-high-water backfilling mining， and overburden isolation grouting backfill mining. The strata control effects of different schemes were analyzed， and the optimal scheme was determined as fully mechanized mining with cemented paste backfilling. Support height was determined according to coal seam thickness， and the working resistance of the support was calculated based on resistance to lateral paste pressure and control of roof subsidence at the filling face. A coordinated “isolation-backfilling-coal mining” process was designed to eliminate mining-filling interference. Based on the roles of the backfilling body during the solidification and coal mining stages， the early strength， stability safety factor， and later-stage strength of the backfilling body were determined. Mix proportion experiments and mechanical property tests of paste backfilling materials were conducted. Results The minimum and maximum structural height of the paste backfilling support are 2.0 m and 3.8 m， respectively， with an extension ratio of 1.9. The working resistance of the support exceeds 8 250 kN. The compressive strength of the paste backfilling body is not less than 0.06 MPa during the solidification stage and not less than 0.16 MPa during the coal mining stage. With a strength stability safety factor of 2.5， the uniaxial compressive strength of the paste backfilling body after 28 days of curing is not less than 2.97 MPa. Economical mix proportions that satisfy strength requirements were obtained for fly ash paste and gangue-fly ash paste backfilling materials.  Conclusions The rational backfilling mining technology and process design for coal seams beneath urban buildings applied at Chengjiao Coal Mines can provide valuable references for similar mines in China.

Key words: coal mining under buildings，water bodies and railways; backfilling mining; backfilling process design; coal seams beneath urban areas; backfilling scheme