沿空留巷底鼓特性与控制方法研究

CHARACTERISTICS AND CONTROL METHOD OF FLOOR HEAVE IN GOB-SIDE ENTRY RETAINING

沿空留巷工程实践中的底鼓观测结果表明,底鼓主要发生在一次回采至二次回采期间,底鼓量达数百毫米,占顶底板移近量的70%以上。底鼓原因是巷道底板在一次回采后发生破裂,底板破裂岩体随后在一次回采和二次回采采动应力的作用下发生峰后蠕变。底鼓量受底板峰后岩性和应力环境的影响较大,随着破裂程度和主应力差的增加而迅速增大。基于这一底鼓特性,提出锚杆法和钢桩法来控制底鼓,锚杆法是通过锚杆锚固力来减小底鼓量,钢桩法是利用钢桩的高抗变形能力和应力拱来减小底鼓量,两者相比,后者对底鼓的控制效果比较显著。研究成果可进一步完善沿空留巷技术,增加其工程应用价值。

The observation results of floor heave in the engineering practices of gob-side entry retaining show that floor heave mainly occurs between the first mining period and the second mining period. The floor heave amount is several hundred millimeters,account for 70% of convergence between roof and floor. The cause of floor heave is discussed. Concretely,the floor rockmass is broken after the first mining and then undergo post-peak creep under the action of the first and second mine-induced stress. The floor heave amount is affected by the lithology and stress environment of floor rockmass. Generally,it increases rapidly as the increase of broken degree and principle stress difference. Based on the characteristics of floor heave,the bolt method and steel pile method are proposed to control floor heave. The bolt method can reduce the floor heave amount by its anchoring force,while the steel pile method by its high deformation resistivity and stress arch. The control effect of latter is more significant. The technology of gob-side entry retaining can be further improved to increase the value of its engineering application by the research results.