Key Takeaways & Executive Findings
- •• Introduces a novel composite stress arch model that more accurately captures stress evolution under repeated mining of close-distance coal seams compared to traditional single arch theories. • Reveals the gradual transformation of a single stress arch into a composite structure, reflecting increasing stress distribution complexity during repeated mining. • Determines that the optimal stop-mining coal pillar width for the Longfeng Coal Mine is between 65 and 70 m, based on numerical simulations and field monitoring. • Establishes a coupling relationship between composite arch evolution and abutment pressure distribution, providing a theoretical basis for coal pillar design and stope stability enhancement.
Abstract
Due to the unique geological structure in the Guizhou region, issues such as stress concentration and inefficient resource utilization efficiency arise during repeated mining of close-distance coal seam. This study focuses on the Longfeng Coal Mine in Guizhou, investigating the evolution of stress arches and abutment pressure distribution under repeated mining conditions through similarity simulations, numerical simulations, and theoretical analysis. The study introduces a novel composite stress arch model, which more accurately represents stress evolution under complex mining conditions compared to traditional single arch theories. The model highlights the gradual transformation of a single stress arch into a composite structure, accounting for the increasing complexity of the stress distribution. Based on these evolution characteristics, a mechanical model of composite arches under nonlinear loading was developed. The calculation results and field monitoring data show that after repeated mining, the stop-mining coal pillar width should be optimized between 65 and 70 m. The research reveals the coupling relationship between the evolution of composite arches and the distribution of abutment pressure, which aids in optimizing coal pillar design, enhancing resource recovery rates, and ensuring the stability of roadways and stopes.
1. Introduction
As an important form of coal resources, the safe and efficient mining of close-distance coal seams has always been a major technical challenge for the coal industry [1−3]. Compared with single-layer coal seam mining, close-distance coal seam group shows more complex response characteristics of surrounding rock in the process of repeated mining, especially the formation and evolution of stress arch structure has a decisive influence on the stability of stope [4, 5]. Stress arch is the key structure that dominates the stress redistribution of surrounding rock in stope, and its spatial form and mechanical characteristics directly determine the evolution law of abutment pressure. Therefore, it is of great significance to study the development law of stress arch for the mining of close distance coal seam group. Accurately grasping the evolution characteristics and distribution law of stress arch can not only reveal the transmission mechanism and distribution characteristics of abutment pressure in mining process, but also provide theoretical basis for the optimal design of stop coal pillar width [6, 7], and effectively prevent the risk of stope instability caused by unreasonable coal pillar width [8, 9].
The classic stress arch theory provides the foundation for understanding the mechanical behavior of rock masses during mining operations. Researchers have both domestically and internationally studied the formation mechanism of stress arches in single-layer mining through physical simulation experiments [10, 11], analyzed their geometric characteristics and stress distribution using numerical simulations [12, 13], and explored their impact on surrounding rock stability through field monitoring [14, 15]. In multi-seam mining research, scholars have revealed the mechanisms of inter-layer stress transfer [16, 17] and structural coupling effects [18, 19], as well as analyzed the influence of working face advance speed [20], inter-layer lithology [21], and geological structures [22, 23]. Concerning the relationship between stress arches and abutment pressure, research indicates that the spatial characteristics of stress arches directly affect the range of advanced abutment pressure [24]. Several methods for determining coal pillar width have been proposed based on stress arch theory, including the limit equilibrium theory design and the abutment pressure peak position method [25, 26]. However, existing studies fail to fully capture the stress arch dynamics during repeated extraction of adjacent coal seams [27, 28]. The digital image correlation (DIC) system for digital speckle monitoring cannot accurately capture the dynamic evolution of stress arches in similarity simulation experiments. Constitutive models commonly used in numerical simulations fail to comprehensively describe the interaction between continuous and discontinuous me
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HU Pin-pin, ZUO Yu-jun, RONG Peng, CHEN Bin, ZHENG Lu-lin, WEN Zhi-jie, HU Jin-chun, REN Wei-de (2026). Effect of composite stress arches evolution on abutment pressure distribution in repeated mining of close-distance coal seams. Journal of Central South University. https://doi.org/10.1007/s11771-026-6201-x
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Frequently Asked Questions
What is the main contribution of this study?
The study introduces a novel composite stress arch model that more accurately represents stress evolution under repeated mining of close-distance coal seams, and reveals the coupling relationship between composite arch evolution and abutment pressure distribution, aiding in coal pillar design and stope stability.
What methods were used in this research?
The research employed similarity simulations, numerical simulations, and theoretical analysis to investigate stress arch evolution and abutment pressure distribution in repeated mining conditions at the Longfeng Coal Mine in Guizhou.
What is the recommended stop-mining coal pillar width?
Based on calculation results and field monitoring data, the optimal stop-mining coal pillar width after repeated mining should be between 65 and 70 meters.
Why is the composite stress arch model important?
Compared to traditional single arch theories, the composite stress arch model better captures the gradual transformation of a single stress arch into a composite structure, accounting for the increasing complexity of stress distribution under complex mining conditions.
What are the practical implications of this study?
The findings help optimize coal pillar design, enhance resource recovery rates, and ensure the stability of roadways and stopes in close-distance coal seam mining, particularly in the Guizhou region.
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