<p>Continuous mining and continuous backfilling (CMCB) provides an effective approach to coordinating resource extraction and environmental protection. However, as CMCB progresses, the load-bearing structure of the backfill–surrounding rock system evolves continuously, while the stage-dependent deformation and failure mechanisms of the roof remain unclear. Taking a representative panel as the engineering background, this study systematically investigates the stage-dependent mechanical response of the roof through theoretical analysis, numerical simulation, and field validation. An elastic foundation beam model is established to derive the roof deflection equation and identify the key controlling factors. The second invariant of the stress deviator (<InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mn>2</mn> </msub> </math></EquationSource> <EquationSource Format="TEX">$J_{2}$</EquationSource> </InlineEquation>) and roof displacement are employed to characterize plastic failure and deformation instability. The results indicate that a uniform stress field is most favorable for maintaining roof stability. In contrast, a vertically dominated stress field promotes <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mn>2</mn> </msub> </math></EquationSource> <EquationSource Format="TEX">$J_{2}$</EquationSource> </InlineEquation> concentration and rock failure, whereas a horizontally dominated stress field is more likely to induce large-deformation instability. The influence of backfill on <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mn>2</mn> </msub> </math></EquationSource> <EquationSource Format="TEX">$J_{2}$</EquationSource> </InlineEquation> evolution and deformation control is more pronounced under horizontally dominated stress conditions. Furthermore, the backfill degree governs the onset of roof support, with higher values enabling earlier load transfer and more effective suppression of roof deformation. Although increasing backfill strength enhances load-bearing capacity, its contribution becomes limited once a critical threshold is exceeded. Based on these findings, targeted optimization measures are proposed for the backfilled roadway, providing guidance for the design and application of CMCB.</p>

Temporal–spatial deformation and failure mechanisms of roof rock beams in roadways under continuous mining and continuous backfilling

期刊论文
发表日期：

2026年5月12日

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Zhaolong Li,
Haoyu Dou,
Renliang Shan,
Jinbo Miao,
Xiao Tong,
Ruifeng Huang

摘要

Continuous mining and continuous backfilling (CMCB) provides an effective approach to coordinating resource extraction and environmental protection. However, as CMCB progresses, the load-bearing structure of the backfill–surrounding rock system evolves continuously, while the stage-dependent deformation and failure mechanisms of the roof remain unclear. Taking a representative panel as the engineering background, this study systematically investigates the stage-dependent mechanical response of the roof through theoretical analysis, numerical simulation, and field validation. An elastic foundation beam model is established to derive the roof deflection equation and identify the key controlling factors. The second invariant of the stress deviator ( $J_{2}$ $J_{2}$ ) and roof displacement are employed to characterize plastic failure and deformation instability. The results indicate that a uniform stress field is most favorable for maintaining roof stability. In contrast, a vertically dominated stress field promotes $J_{2}$ $J_{2}$ concentration and rock failure, whereas a horizontally dominated stress field is more likely to induce large-deformation instability. The influence of backfill on $J_{2}$ $J_{2}$ evolution and deformation control is more pronounced under horizontally dominated stress conditions. Furthermore, the backfill degree governs the onset of roof support, with higher values enabling earlier load transfer and more effective suppression of roof deformation. Although increasing backfill strength enhances load-bearing capacity, its contribution becomes limited once a critical threshold is exceeded. Based on these findings, targeted optimization measures are proposed for the backfilled roadway, providing guidance for the design and application of CMCB.