ZHANG X Y , ZHANG G J, XU L F, et al. Research on optimization and effect analysis of deep-hole pre-splitting blasting parameters for overlying strata during the final mining stage of fully mechanized top-coal caving under a thick coal seam with a hard roof[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(2):31-42.

doi:10.16186/j.cnki.1673-9787.2025040043

Received:2025/04/23

Revised:2025/10/29

Published:2026/01/28

Research on optimization and effect analysis of deep-hole pre-splitting blasting parameters for overlying strata during the final mining stage of fully mechanized top-coal caving under a thick coal seam with a hard roof

Zhang Xiangyang1,2, Zhang Gaojun1,2, Xu Linfeng1,2, Wang Chongkai1,2

1.State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection， Huainan  232001， Anhui， China；2.School of Mining Engineering， Anhui University of Science and Technology， Huainan  232001， Anhui， China

Abstract: Objectives To ensure the safe withdrawal of hydraulic supports during the final mining stage of a fully mechanized top-coal caving face under a thick coal seam with a hard roof， this study investigates the optimization of deep-hole pre-splitting blasting parameters and evaluates the pressure-relief effectiveness of roof cutting in the overlying strata. Methods Taking the 12314 working face in the Wangjialing mining area as the engineering background， a structural mechanics model and a numerical model of a large-space stope during the final mining stage were established. A dynamic coupling analytical method between the overlying strata load and the support bearing capacity was developed， and a stress-blocking positioning method for roof cutting and pressure relief was proposed.  Results During the final mining stage， the cantilever length and height of the roof structure were identified as the dominant factors controlling support loading. Increasing the roof-cutting height and reducing the distance between the cutting position and the stop line significantly enhanced the stress-blocking effect. The stress-blocking efficiency gradually stabilized with increasing roof-cutting height， with a critical height of 35 m. In contrast， the stress-blocking effect weakened as the distance between the roof-cutting position and the stop line increased， with a critical distance of 60 m. Based on the nonlinear relationship between roof-cutting parameters and pressure-relief indicators， a prediction model for roof-cutting pressure-relief effectiveness was developed using surface fitting， achieving a prediction error of only 3.32%. Under the optimal roof-cutting parameters for the 12314 working face （roof cutting conducted 35 m ahead of the stop line with a cutting height of 30 m）， the peak advanced support stress was reduced by 25.93%， the maximum roof subsidence decreased by 14.10%， and the peak stresses on the left and right sides were reduced by 9.83% and 5.50%， respectively. Conclusions The designed combination of roof-cutting parameters for the final mining stage exhibits a pronounced stress-blocking and pressure-relief effect， effectively ensuring the safe withdrawal of hydraulic support. The proposed prediction model enables rapid calculation and visualization of multiple pressure-relief indicators， facilitating the design and optimization of key parameters for deep-hole pre-splitting blasting. Furthermore， the research framework of "theoretical analysis-numerical simulation-prediction analysis-on-site verification" and the standardized procedure for roof-cutting parameter design provide a valuable reference for similar engineering applications.

Key words: thick coal seam with a hard roof; deep-hole pre-splitting blasting; roof cutting and pressure relief; roof-cutting height; roof-cutting position