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Coal Engineering ›› 2026, Vol. 58 ›› Issue (3): 94-103.doi: 10.11799/ce202603012

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Evolution Law and Control of Plastic Zone of Surrounding Rock in Soft Rock Mining Roadway of Thick Coal Seam

  

  • Received:2025-01-09 Revised:2025-02-25 Online:2026-03-10 Published:2026-04-14

Abstract:

The width of the plastic zone in the vicinity of rock around a roadway is a crucial factor for determining the support design parameters. This study investigates the deformation and failure patterns of the rock surrounding the roadway by examining the effects of varying lateral pressure coefficients, rock types, and depths of roadway burial through theoretical analysis, numerical simulation, and field testing. The findings reveal several key points : (1) With lateral pressure coefficient as the variable, the plastic zone's irregularity around the roadway increases as the coefficient decreases. The shape of the plastic zone evolves from circular to elliptical, then to a butterfly pattern, and finally stabilizes in a butterfly form. The plastic zone at the roof and floor narrows while that at the sides widens, with the roof and floor changes being more pronounced. At a lateral pressure coefficient of 0.8, the plastic zone's distribution and width at the roof, floor, and sides of the roadway are similar. (2) When considering rock type, the plastic zone width in fine-grained sandstone is significantly less than in coal seams. The stronger the overall rock, the smaller the plastic zone's failure width. Shear failure is the primary mode of plastic zone failure, with greater deformation at the sides compared to the roof and floor. Different rock types influence the plastic zone's width but not its shape. (3) Based on the plastic zone's growth pattern in the rock surrounding the roadway, the use of high pre-stressed bolts (or cables) is recommended, with extended lengths and increased diameters to enhance the elongation and strength of the bolts (or cables). Field tests indicate that the optimized support system effectively manages the separation and deformation failure of the roadway. The rock's deformation is kept within 300 mm, significantly enhancing its internal stability and reducing roadway deformation.

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