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褶曲构造内陷落柱形成机理及巷道支护技术

Formation mechanism of subsidence column in fold structure and roadway support technology

  • 摘要: 为了确保长平煤矿43211、43212巷安全快速地通过陷落柱,同时保证后期回采过程中破碎带巷道围岩的稳定,在分析矿井褶曲构造内陷落柱的形成机理、数值仿真原始应力状态的基础上,提出了前期须锚网带与架棚主被动联合支护、中期须注浆加固围岩、后期巩固围岩强度的支护措施。研究结果表明:溶洞形成后,原岩应力发生变化,由于不同层位的岩层受张力与挤压力作用,背斜构造陷落柱截面呈正楔形,而向斜构造中陷落柱形状则反之;正楔形陷落柱在正常岩层边界产生局部应力集中,柱体内垂直应力整体呈低应力状态,柱体内水平应力小于正常岩层应力;现场初期支护使用主被动联合支护措施作用于应力集中带,中期取合理注浆滞后时间20 d,采取深部、浅部混合注浆模式,后期为了防止外载荷的扰动进一步巩固围岩强度,采用架棚支护提高柱体影响带强度,矿压监测围岩状态稳定。

     

    Abstract: To guarantee the roadways of No.43211 and No.43212 of Changping Coal Mine pass through the collapsed pillars safely and quickly and the stability of the roadway surrounding rock in the broken zone in the following mining process, the formation mechanism of the subsidence column in the fold structure in the mine and numerical simulation of the original stress state are regarded as the theoretical basement. The authors proposed the reinforcement measures including the pre-anchor net, the shed passive joint support, reinforcing surrounding rock by medium-term grouting and later-stage strength of surrounding rock. The results show that the original rock stress changes after the formation of karst cave. Because of different layers of rock under tension and pressure anticline collapse column section shows the positive wedge geometry. While the syncline collapse column is adverse,local stress concentration occurs at the boundary of normal rock strata for a wedge-shaped subsidence column, and overallthe vertical stress in the column is low. The horizontal stress in the column is less than that in the normal rock strata. The combined support measures are used to act on the stress concentration zone in the initial stage in the field. In the middle stage, reasonable grouting lag time is 20 days. The deep and shallow mixed grouting mode is adopted. In the later stage, to prevent disturbance of external load and further consolidate the strength of surrounding rock, roof support is used to enhance the strength of column fracture zones. Monitoring results of the field stress showed that the surrounding rock is stable.

     

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