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坚硬顶板动压巷道远近应力场演化规律及调控技术研究

Evolution laws and control technology of near and far stress field in hard roof mining roadway

  • 摘要: 针对坚硬顶板强动压巷道围岩变形破坏难控制的问题,以寺家庄15119回风巷为工程背景,采用理论分析、现场实测、数值模拟与工业试验的综合研究方法,研究了坚硬顶板回采巷道远近应力场演化规律及调控技术。研究表明:15119回风巷在留设25 m煤柱时由于坚硬顶板难垮落造成远场应力集中,且在演化过程中加剧了巷道围岩近场应力环境恶化,这是致使该类巷道围岩变形破坏的问题所在。巷道围岩远近应力场存在紧密的相互作用关系,远场的应力能够引起近场应力范围和大小的变化,从而对巷道围岩的变形与破坏时效及范围产生影响。基于此,提出了巷道围岩的远场与近场应力场调控原理,即在通过工程干预手段有效地调控远近应力场的分布、传导途径及其相互作用,以此实现围岩应力环境的优化和巷道稳定性的增强。依据该原理,提出了“无煤柱留墙掘巷+切顶卸压+强力支护”远近应力场调控技术方案,新方案先调整15119回风巷至邻近15117工作面1.5 m处的低应力区,然后在15117进风巷顶板水压裂预制裂缝卸压调控远场应力分布与传播途径,最后强化15119回风巷围岩支护,优化近场应力环境。工业性试验表明:新方案能够有效减弱远场应力对近场应力的叠加作用,新方案中压裂对应的15119回风巷顶底板移近量最大460 mm,两帮收缩量最大为430 mm,断面收缩率降低了26.1%。巷道围岩远近场应力调控方案取得了良好的控制效果,可为类似巷道提供理论依据与技术参考。

     

    Abstract: In response to the challenge of controlling deformation and damage in hard roof strong mining roadways, the study, taking the 15119 return airway of Sijiazhuang as an engineering background, employs a comprehensive research methodology combining theoretical analysis, field measurements, numerical simulations, and industrial experiments to investigate the evolution patterns of stress fields in hard roof mining roadways at various distances and the corresponding control techniques.Research indicates that when a 25-meter coal pillar is retained in the mining area of 15119 Hui Feng Lane, the difficulty in collapsing the hard roof causes stress concentration at a distance. Furthermore, this condition exacerbates the deterioration of the near-field stress environment surrounding the roadway during its evolution, which is the underlying issue leading to deformation and failure of the roadway’s surrounding rock.The stress fields of the surrounding rock in roadways exhibit a close interaction; fluctuations in the distant stress field can induce changes in the range and magnitude of the local stress field, thereby affecting the deformation and failure timing and extent of the roadway surrounding rock.Based on this understanding, the principle of regulating both the distant and local stress fields of roadway surrounding rock has been proposed. This involves the effective reallocation of the distribution and transmission pathways of the stress fields through engineering interventions, thereby optimizing the stress environment of the surrounding rock and enhancing the stability of the roadway. Based on the principle, the “pillarless mining with retained wall + roof cutting for pressure relief + enhanced support” method has been proposed to regulate the stress fields both in proximity and at a distance. The new strategy initially adjusts the low-stress zone near the 15119 return airway to 1.5 meters from the adjacent 15117 working face. Subsequently, hydraulic fracturing is utilized to create predetermined fractures in the roof of the 15117 intake airway, thereby controlling the distribution and propagation paths of the far-field stress. Finally, the support for the surrounding rock of the 15119 return airway is strengthened to optimize the near-field stress environment.Industrial trials of the new scheme indicate its efficacy in mitigating the impact of far-field stress on near-field stress. The maximum convergence of the roof and floor in the 15119 return airway, associated with the hydraulic fracturing of the new scheme, is 460 mm, and the maximum rib convergence is 430 mm, resulting in a 26.1% reduction in cross-sectional shrinkage rate. Consequently, the rock surrounding the gallery’s stress control scheme for both far-field and near-field has been proven effective, providing a theoretical basis and technical reference for similar galleries.

     

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