顶升可缩式钢管混凝土支柱试验研究与工程应用

Experimental study and engineering application of jacking retractable concrete filled steel tubular column

  • 摘要: 针对沿空留巷巷旁支护存在的问题,提出基于顶升可缩式钢管混凝土支柱的巷旁支护技 术。 设计了顶升可缩式钢管混凝土支柱结构与留巷工艺,为验证该支柱增阻让压性能,开展了不同 让压结构的可缩承载试验,研究表明:杨木可缩阶段承载力 200 kN、极值承载力 700 kN,松木可缩 阶段承载力 500 kN、极值承载力 900 kN,钢筋网柱可缩阶段承载力 400 kN、极值承载力 750 kN,以 松木的压缩率最高,达到77.7%,可见,松木更适合作为让压结构。 通过分析钢管混凝土短柱和长 柱承载力试验结果,验证了钢管混凝土支柱高承载力特征,修正了支柱承载力长细比折减系数,优 化了顶升可缩式钢管混凝土支柱承载力计算公式。 通过文献分析选取了合理的巷旁支护阻力和压 缩量计算方法,以鲁西煤矿 3下 A02 工作面沿空留巷为例,进行了巷旁支护阻力和压缩量计算分析, 以试验研究为基础,开展了顶升可缩式钢管混凝土支柱结构设计、支柱受力分析和工程实践研究。 实践表明采用单排 φ299 mm×10 mm 顶升可缩式钢管混凝土支柱+一排 φ21.6 mm×10 300 mm 控顶 锚索的巷旁支护,辅以挡风帘+网喷层的采空区隔离方案,能够保证沿空留巷长期稳定,该技术具 有顶升初撑效果好、增阻变形能力强、支护承载力高等特点,在基本顶沉降运动剧烈的留巷工程中 具有较好的应用前景,若进一步配合采空区侧切顶卸压和支柱外壳钢管回收复用,留巷效果将 更优。

     

    Abstract: To overcome the issue that exists in gob side entry retaining, a gob side entry retaining technology based on jacking retractable concrete filled steel tubular column was proposed. A new jacking retractable concrete filled steel tubular column structure and roadway retaining technology was developed. In order to verify the resistance increase and pressure relief performance of the column designed, the compressible bearing tests of different pressure relief structures were carried out. The results show that the stable bearing capacity of poplar in the shrinkable stage is 200 kN and the extreme bearing capacity is 700 kN. The stable bearing capacity of reinforced mesh column in the shrinkable stage is 400 kN and the extreme bearing capacity is 750 kN. Correspondingly, the stable bearing capacity of pine in the shrinkable stage is 500 kN and the extreme bearing capacity is 900 kN, the compression rate of pine is the highest, reaching 77.7%, indicating that pine is more suitable as pressure relief structure. Through the analysis of the bearing capacity test of the long and short columns, the high bearing capacity characteristics of jacking columns were verified, the reduction factor of slenderness ratio of the column bearing capacity was modified, and the calculation formula for the ultimate bearing capacity of the columns in compression stage and stability stage was obtained. By summarizing and analyzing various calculation methods, the calculation formulas of roadway side support resistance and reasonable compression in line with the technology of jacking retractable concrete filled steel tubular column were given. According to the project background in the retaining roadway along the goaf at the A02 working face in the 3rd lower section of Luxi Coal Mine, the resistance and compression of roadway side support were analyzed. Then, on the basis of the experiment, the bearing capacity and force analysis of the retaining roadway were carried out according to the pillar structure design. The results of engineering practice show that the support scheme of one row 299 mm×10 mm jacking retractable concrete filled steel tubular column and one column 21.6 mm×10 300 mm roof control anchor cable, combined with “wind curtain to isolate goaf + net spraying layer” meets the requirements of roadway stability. The support technology has the characteristics of good jacking effect in the initial stage, strong resistance increasing deformation capacity and high supporting force in the later stage. It has a good application prospect in the roadway retaining project where the basic roof settlement movement is violent, and the roadway retention effect will be better if it is further combined with the pressure relief of side cutting roof in goaf and the recovery and reuse of pillar shell steel pipes.

     

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