Dynamic Mechanical Properties of Coal Under Impact Loading

The response of coal to rapid loading is governed by its dynamic mechanical properties, which encompass strength, deformation behaviour and energy dissipation characteristics under high strain‐rate impact. In underground mining and deep excavation contexts, sudden stress waves induced by rock bursts or blasting impose dynamic tensile and compressive loads that may trigger abrupt failure, gas outbursts or fragmentation. Coal exhibits rate‐dependent strength enhancement up to a threshold beyond which brittleness dominates, leading to rapid crack coalescence and fragment ejection. Moisture content, inherent heterogeneity and pore structure modulate energy absorption and crack propagation paths. Advances in experimental methods and constitutive modelling have elucidated the interplay between inertia effects, fluid–solid interactions and microstructural evolution, enabling predictive simulation of dynamic damage in coal seams. Understanding these properties is crucial for designing effective support systems, optimising blasting protocols and mitigating dynamic hazards in coal mining.

Research from Nature Portfolio

Recent studies have employed split Hopkinson pressure bar testing combined with ultra-high-speed digital imaging to investigate how varying water content alters dynamic tensile behaviour. These experiments revealed that increasing moisture reduces coal brittleness and enhances ductility, shifting stress–strain curves through four distinct stages from initial compaction to rapid rupture. Quadratic relations describe the variation of peak stress and strain with water content, while rate sensitivity is heightened in saturated samples. Under high-rate loading, inertia and the hydraulic resistance of pore water impede crack initiation and propagation, thereby elevating dynamic strength. These insights furnish a theoretical foundation for strategies to prevent rock bursts by managing moisture conditions and loading rates in active coal faces.

Dynamic Mechanical Properties of Coal Under Impact Loading publication trend

The graph below shows the total number of articles in dynamic mechanical properties of coal under impact loading across all publications each year (not limited to Nature Index journals).

Technical terms

Split Hopkinson Pressure Bar (SHPB): A laboratory apparatus that generates high‐rate stress waves to characterise material response under impact loading.

Strain rate: The rate of deformation over time, typically expressed in s⁻¹, which strongly influences strength and failure mode in dynamic tests.

Dynamic tensile strength: The peak tensile stress a material can sustain during high‐rate or impact loading before failure.

Constitutive model: A mathematical formulation describing a material’s stress–strain behaviour under various loading rates and conditions, essential for numerical simulation of dynamic events.

References

1. Dynamic tensile properties, deformation, and failure testing of impact-loaded coal samples with various water content. Scientific Reports (2021).
2. Dynamic characteristics and crack evolution laws of coal and rock under split Hopkinson pressure bar impact loading. Measurement Science and Technology (2023).
3. Developing a New Bursting Liability Index Based on Energy Evolution for Coal under Different Loading Rates. Sustainability (2022).
4. Determination of Holmquist–Johnson–Cook Constitutive Parameters of Coal: Laboratory Study and Numerical Simulation. Processes (2019).