软岩巷道钢桁架力学性能试验及支护研究

Mechanics performance testing and research of truss support in the soft rock roadway

我国煤矿深部软岩巷道大地压、强流变、大变形等问题突出,此类巷道稳定需要较大的支护力,因此提出全圆钢桁架支架支护技术。桁架采用8段双层12#工字钢构件组成,每段构件之间连接采用端头焊接390 mm×800 mm×30 mm钢板和螺栓连接,在实验室借助分步多次逐级加载、测试系统测试了全圆钢桁架支架在垂向和水平向荷载按不同比例组合作用下的极限荷载和极限变形量。试验结果表明:在均压荷载作用下,钢桁架的极限承载力为1 500 t,弹性极限压缩变形为12.18 mm;非均压荷载组合比值为0.2时,支架极限承载力为900 t,弹性极限变形为26.3 mm;极限荷载破坏方式为连接块处的错动和支架直径收缩变形破坏。与传统U型钢支架相比,钢桁架支护反力提高10倍以上。针对极软岩巷道变形规律,提出恒阻大变形锚杆索+预留变形量的一次支护,在高预紧力支护下通过恒阻装置释放变形能并形成锚网索-围岩耦合支护圈,然后采用全圆钢桁架强力二次支护,在均压下发挥钢桁架的最佳支护力学性能,其支护方式在深部大地压、强流变软岩巷道中有着广泛的应用前景。

The roadway with soft rock has such problems as high ground pressure, strong rheology, and large deformation in deep coal mining in China, so the large supporting force is needed to stabilize the surrounding rock. The author has put forward a new technology with truss support, and the truss is made of eight 12# double I-Beams. Each beam connects another beam with 390 mm×800 mm×30 mm welded steel plate and bolted connection. In laboratory the truss mechanical property about ultimate load and deformation has been achieved by the monitoring system with different combination with horizontal load and vertical load that is stepwise added. The results have shown that under the uniform pressure ultimate bearing capacity of the truss is 1 500 t, and the ultimate deformation is 12.18 mm; when the ratio of the vertical load to the horizontal load is 0.2, ultimate load of the truss is 900 t, and the elastic deformation limit is 26.3 mm; and the failure is the connection slide and the diameter shrinkage damage. Compared with the traditional U-shaped steel, the double truss support counterforce has been increased to 10 times. In the soft rock roadway, the author has put forward the first support with constant-resistance large-deformation anchor coupling support and reserved deformation; the support can release the deformation energy. After forming the anchor-surrounding rock coupling support circle, the strong truss force support has been used in the second support; this way can make full use of mechanical property. The truss structure may have an extensive application in fields of the deep roadway with the soft rock, high ground pressure and strong rheology in future.