Wu P F, Ge Z B, Guo W B. Grouting and settlement reduction technology for thin bedrock with thick loose layers and its engineering application［J］. Journal of Henan Polytechnic University（Natural Science），DOI:10.16186/j.cnki.1673-9787.2026050035

doi: 10.16186/j.cnki.1673-9787.2026050035

Received：2026-06-01

Revised：2026-10-26

Online：2026-10-29

Grouting and settlement reduction technology for thin bedrock with thick loose layers and its engineering application

Wu Pengfei ¹, Ge Zhibo ², Guo Wenbing ^2，3

（1. Xinzheng Coal Electricity, Zhengzhou Coal Industry Group, Xinzheng 451100, Henan, China；2. School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo 454003，Henan, China；3. Collaborative Innovative Center of Coal Safety Production in Henan Province，Jiaozuo 454003， Henan, China）

Abstract: [Objective]  To effectively control surface subsidence under the special geological conditions of thin bedrock with thick loose layers, liberate stranded coal resources, mitigate land collapse and ecological damage caused by “three-down” coal pressure, and address the prominent conflict between resource development and ecological protection. [Methods] A combined approach of theoretical analysis and on-site engineering experiments was adopted to systematically carry out research and engineering verification of loose layer grouting subsidence reduction technology, aiming to provide a new approach for green mining in mining areas with similar geological conditions. [Results] （1） Based on the analysis of the lithological characteristics of the loose layer, it was determined that sandy layers with good pore connectivity should be prioritized for grouting, while low-permeability clay layers should serve as grouting protective layers; （2） A thick loose layer grouting subsidence reduction field test project was successfully designed and implemented, with a cumulative consumption of 39,960.72 t of dry fly ash. Engineering practice verified the feasibility of this technology under mining geological conditions of thin bedrock with thick loose layers; （3） Key process parameters were revealed, clarifying the lithological characteristics of suitable grouting layers, dynamic evolution rules of grouting pressure, slurry diffusion radius, and the reasonable spacing between grouting layers and coal seam roof. A grouting start-stop determination criterion was established centered on the multi-parameter coordinated regulation of “pressure-flow rate-grouting volume”;（4） Based on on-site measured data, the probabilistic integral method was used to invert the estimated surface subsidence value without grouting. When the extraction-to-injection ratio is 0.09, the surface subsidence reduction rate reaches 19.9%. [Conclusion] This study verified the feasibility of loose layer grouting subsidence reduction technology under geological conditions of thin bedrock with thick loose layers, and has significant engineering implications for promoting green coal resource exploitation and ensuring the sustainable development of mining areas.

Key words: thin bedrock; loose layer grouting; subsidence control; green mining

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