Hydraulic Fracturing and Strata Behavior in Coal Mining

Hydraulic fracturing has emerged as a targeted approach for managing the stability of overlying rock masses during coal extraction. By injecting pressurised fluid into high-level hard rock layers, controlled fractures are created that alleviate stress concentration, reduce dynamic loading on supports and guide roof collapse in a predictable manner. The technique complements traditional blasting and support methods by enabling selective weakening of key strata and by improving the connectivity of fracture networks. Strata behaviour in coal mining encompasses the deformation, breakage and energy release patterns of overburden layers as mining progresses. Strong and thick strata often form cantilever and voussoir beam structures that transfer high loads to the working face, resulting in periodic weighting events, rock bursts and ground pressure phenomena. Modern investigations combine numerical simulation, in situ monitoring and physical modelling to unravel the evolution of fracture systems, the migration of elastic energy and the interplay between loose layers, faults and hard roofs. Understanding these processes is vital for safe production in deep and super-thick coal seams, where large-space gob areas and complex geology amplify the risk of sudden roof collapses, seismicity and gas outbursts. Recent advances have focused on optimising fracture placement, fluid properties and support design to synchronise strata failure with goaf filling, thereby ensuring controlled caving and minimising hazardous energy accumulation.

Research from Nature Portfolio

Recent studies have demonstrated the potential of water-mediated blasting as a hybrid approach that merges hydraulic fracturing concepts with conventional blasting. Investigations into the mechanical characteristics of aqueous media in open-pit operations reveal that water confers a higher energy transfer coefficient and induces peak principal stresses significantly above those generated in air media. Finite-element simulations of borehole dynamics show systematic growth in stress concentration around fractures as water content increases, yielding enhanced fragmentation and reduced dust emissions. Field trials have confirmed a dust suppression rate exceeding 70 % and improved loading efficiency, indicating that water-assisted fracture propagation can be translated into effective engineering applications for roof and slope control in coal mines.

Hydraulic Fracturing and Strata Behavior in Coal Mining publication trend

The graph below shows the total number of articles in hydraulic fracturing and strata behavior in coal mining across all publications each year (not limited to Nature Index journals).

Technical terms

Hydraulic fracturing: Injection of pressurised fluid into rock strata to initiate and propagate fractures for stress relief and controlled failure.

Overburden: The rock and soil layers that lie above a coal seam and respond to mining-induced deformation.

Key strata: Strong, thick rock layers that span large areas and dictate the load transfer and failure modes of overlying strata.

Goaf: The void space left after coal extraction, into which fractured strata are designed to collapse.

Pressure relief fracturing: Targeted fracturing technique aimed at reducing stress concentration around excavations by creating controlled discontinuities.

References

1. Influence of coupling mechanism of loose layer and fault on multi-physical fields in mining areas. International Journal of Coal Science & Technology (2023).
2. Research on blasting mechanism and blasting effect of aqueous media in open pit coal mines. Scientific Reports (2023).
3. Controlling mine pressure by subjecting high-level hard rock strata to ground fracturing. International Journal of Coal Science & Technology (2021).
4. Determination of fracture location of double-sided directional fracturing pressure relief for hard roof of large upper goaf-side coal pillars. Energy Exploration & Exploitation (2019).
5. In Situ Studies on the Characteristics of Strata Structures and Behaviors in Mining of a Thick Coal Seam with Hard Roofs. Energies (2018).