Grouting Techniques for Coal Mine Subsidence Control

Grouting has become an indispensable strategy for mitigating surface subsidence and enhancing rock‐mass stability in coal mining regions worldwide. By injecting cementitious, polymeric or admixture‐based slurries into fractures, voids and bed separations within the overburden, grouting techniques pre‐emptively fill potential collapse zones and reinforce load‐bearing strata. Variants include overburden‐separation grouting, which targets induced cleavages between key strata; isolated grout injection beneath hard layers to compact bulking rock masses; and bed separation backfill grouting, in which gangue or fly‐ash slurries restore cohesion in fractured zones. Recent advances in material science have yielded delayed‐expansion sealing capsules and modified slurries with controlled diffusion radii, reducing leakage and optimising grout take. Concurrently, numerical and physical simulation platforms now enable real‐time monitoring of slurry flow, pressure distribution and consolidation behaviour, allowing schemes to be tailored to local geology, fault networks and hydraulic conditions. Together, these developments support more sustainable mining practices, limit environmental impact and protect surface infrastructure over extensive coalfields.

Research from Nature Portfolio

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Research from all publishers

Recent work has demonstrated that overburden-separation grouting can both limit surface subsidence and alter gas emission patterns within the stope, with numerical simulations showing how variations in grouting pressure shift stress relief zones and reduce escape routes for methane. In parallel, novel predictive methodologies that treat the post-mining coal–rock mass as an elastic foundation beam, combined with equivalent mining height theory, have produced subsidence forecasts matching field observations to within a few per cent and helped identify optimal injection–extraction ratios. Complementing these field and theoretical studies, three-dimensional laboratory visualisations of slurry “diffusion–bleeding–seepage” have mapped semi-elliptical flow profiles, quantified water–cement separation effects and established key saturation thresholds, thereby guiding the design of more efficient grouting programmes.

Grouting Techniques for Coal Mine Subsidence Control publication trend

The graph below shows the total number of articles in grouting techniques for coal mine subsidence control across all publications each year (not limited to Nature Index journals).

Technical terms

Grouting: Injection of fluid materials into rock fractures or voids to reinforce strata and control subsidence.

Overburden-separation grouting: High-pressure injection into induced separation layers within the overburden to support key strata and limit surface movement.

Bed separation: Detachment of overlying rock layers from principal strata, creating voids targeted by grouting techniques.

Goaf: The collapsed and bulking rock mass remaining after coal extraction, often subject to compaction and reinforcement by grouting.

Elastic foundation beam model: A theoretical framework representing key strata as a beam on an elastic foundation, used to predict deflection and subsidence under varying grouting conditions.

Equivalent mining height theory: Concept that translates complex mining-induced subsidence into an equivalent uniform extraction height for simplified predictive modelling.

References

1. Strata Movement of Overburden-Separation Grouting Working Face and Its Influence on Gas Emission during Mining. Sustainability (2023).
2. Compaction Response of Mining-Induced Rock Masses to Longwall Overburden Isolated Grouting. Minerals (2023).
3. Delayed-Expansion Capsule Sealing Material for Coal Mine Overburden Isolated Grouting. Applied Sciences (2024).
4. Slurry Leakage Channel Detection and Slurry Transport Process Simulation for Overburden Bed Separation Grouting Project: A Case Study from the Wuyang Coal Mine, Northern China. Water (2023).
5. Experimental method and application of the slurry “diffusion-bleeding-seepage” of isolated overburden grout injection. Frontiers in Earth Science (2023).
6. Subsidence Prediction Method Based on Elastic Foundation Beam and Equivalent Mining Height Theory and Its Application. Applied Sciences (2024).
7. Experimental Study on the Diffusion Radius of Modified Slurry Used in Longwall Overburden Isolated Grouting. Geofluids (2023).