Research and application of combined load-bearing shell support for deep soft rock roadway
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摘要: 深部软岩巷道支护问题影响因素多、情况复杂,理论研究工作仍处于探索阶段,而依靠提高支护材料强度和采用注浆锚杆无法从根本上解决该问题,且成本高。分析了深部软岩巷道表层围岩应力分布情况,其变形特点为应力向深部转移,巷道表层围岩应力降低但变形量较大,得出解决深部软岩巷道支护难题的关键是在尽可能提高支护结构强度的同时,降低支护结构周边切向应力,即合理设计内层支护小结构、构筑中间应力消减层,使其与外层原岩大结构共同作用,形成深部软岩巷道支护体系,增强围岩自承能力。根据内层支护小结构的要求,提出了主动支护和被动支护相结合的锚架注组合承载壳全断面联合支护技术,即在锚杆(索)支护的基础上,采用型钢支护联合壁后充填结构形成具有一定厚度和较高强度的内层支护结构体,从而减少顶板、煤壁和空气接触,同时充填注浆材料全断面向深部软岩裂隙扩散凝固,钢架在围岩发生一定让压变形后起到径向约束作用,可强化围岩承压环,保证围岩稳定性。针对丁集矿西二采区回风石门修复工程,采用高预紧力锚索+U型钢棚+注浆的锚架注组合承载壳全断面联合支护结构,通过深孔爆破方法构筑中间应力消减层。矿压观测结果表明,巷道两帮移近量最大值为349 mm,顶板下沉量最大值为323 mm,巷道变形得到有效控制。Abstract: There are many influencing factors and complex conditions in deep soft rock roadway support. The theoretical research is still in the exploratory stage. Moreover, the method of relying on improving the strength of support materials and the use of grouting bolts can not fundamentally solve the problems and the cost is high. This paper analyzed the stress distribution of deep soft rock roadway surface surrounding rock. The deformation characteristic was that the stress transferred to deep mine and the stress of roadway surface surrounding rock reduced while the deformation increased. It was found that the crucial methods to solve the deep soft rock roadway support problems are to maximize the strength of supporting structure and to reduce the tangential stress around the supporting structure. This meant that the small inner supporting structure should be well designed and the intermediate stress reduction layer should be constructed. The inner supporting structure and the large outer structure of original rock were designed to form a deep soft rock roadway support system to enhance the self-supporting capacity of surrounding rock. According to the requirement of the small inner supporting structure, a full-section anchor shed grout joint support technology of load-bearing shell combined with active and passive support was proposed. On the basis of anchor (cable) support, steel supporting structure and filling structure behind walls formed inner supporting structure with certain thickness and high strength. Therefore, the structure reduced the contact between the roof, the coal wall and the air. At the same time, the filling grouting material spread and solidified in the deep soft rock cracks. The steel frame acted as a radial restraint after certain pressure-relief deformation of the surrounding rock, which could strengthen the surrounding rock load-bearing ring and ensure the stability of the surrounding rock. In the windstone gate restoration project of No.2 West Mining Area of Dingji Coal Mine, a full-section anchor shed grout joint support technology of high preload anchor cable + U-shaped steel shed + anchor shed grout injection was adopted. And the intermediate stress reduction layer was constructed by deep hole blasting method. The mine pressure observation results showed that the maximum value of the two sides of the roadway was 349 mm, the maximum value of the roof subsidence was 323 mm and the roadway deformation was effectively controlled.
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