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动载扰动下深部大断面硐室围岩“帮-顶”联动失稳机理

Mechanism of connected instability of “rib-roof” in deep large section chamber under dynamic disturbance

  • 摘要: 动载扰动下深部大断面硐室围岩结构性破坏与失稳是大型现代化煤矿面临的突出问题。以新巨龙煤矿井下典型煤矸分选大断面硐室为背景,基于FLAC3D模拟软件研究了动载扰动与高静载应力叠加下典型大断面硐室围岩变形破坏演化过程,揭示了典型动载扰动下深部大断面硐室“帮-顶”联动失稳机理,提出了多层次控制技术。研究表明:①动载扰动过程中,深部大断面硐室从帮部极限平衡区“板裂结构”率先破坏,联动诱发顶板锚固岩层的垮冒,最终表现为整个硐室围岩的失稳。②动载扰动是深部大断面硐室围岩失稳的诱发因素,而帮部极限平衡区应力是基础力源;③动载扰动下深部大断面硐室围岩失稳防控应从弱化动载应力和均衡强化锚固承载能力2方面入手,即采用深部消波吸能-浅部全断面锚固均撑支护-巷表柔性防护多层次控制技术。模拟表明,该技术控制了大断面硐室失稳,围岩塑性区体积下降了18.46%,变形量降幅高达31.78%,帮部与顶板整体性得到了强化。

     

    Abstract: Dynamic disturbance induced surrounding rock failure and instability of deep large-section chamber is a prominent problem in large modern coal mines. Based on geological conditions of the typical large-section chamber for coal gangue separation in Xinjulong Coal mine,firstly,this paper studies the deformation and failure evolution process of the surrounding rock of the typical large-section chamber under the dynamic disturbance coupling high static stress using the FLAC3D simulation software,and then reveals the mechanism of connected instability of “rib-roof” in deep large section chamber under dynamic disturbance. Finally,an integrated multi-level security control strategy is proposed. The results indicate that:① during dynamic disturbance,the "slab-rent structure " in the limit equilibrium area of the deep large-section chamber rib was first broken,and then the caving or roof fall of anchorage roof was activated and finally instability of deep large-section chamber was ultimately manifested. ② Dynamic disturbance is the inducing factor of surrounding rock instability of deep large-section chamber,and the high static stress in the limit equilibrium zone is the basic force source. ③ The prevention of surrounding rock instability induced by dynamic disturbance should integrate weakening dynamic load and strengthening anchorage bearing capacity together. For this reason,an multi-level security control strategy integrated the"Stress wave elimination and energy absorption in deep part of chamber-full section anchorage support in shallow part-flexible protection on chamber sufure". The results show that after adopting this technology,the instability of deep large-section chamber was restrained,and the volume of the plastic zone is reduced by 18.46% and the deformation of surrounding rock decrease and the decreasing amplitude is up to 31.78%.

     

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