柠条塔矿切顶成巷水射流切缝技术试验

切顶成巷工艺关键技术为顶板定向切缝,传统切缝技术均采用爆破技术,其存在较多问题。本文以柠条塔矿切顶成巷工程为背景,改良顶板定向切缝技术,开展水射流切缝技术试验,试验目标要求切缝后相邻钻孔之间的岩体损伤率达到90%以上,并且切缝应成一条直线,进而保证切顶成巷工艺中顶板切缝效果。试验系统主要由泵站压力系统、磨料供给装置、切割头输送装置、切割头、定向器与现场试验所用磨料构成。试验过程中首先在顶板岩层中预先钻进4个钻孔,然后通过输送装置及高压密封钻杆在割缝孔中定向安装切割头,利用高压水射流分别沿4个切缝孔的径向向相邻钻孔造缝,定向连通所有切缝孔,进而形成定向裂缝面。试验结果裂缝基本呈直线,裂缝偏转角度最大为0-10°,但在四个孔切缝过程中,孔内较为直观的裂缝尚未贯穿整个钻孔的孔壁。该结果表明水射流切缝技术无法实现设计要求中形成90%贯通切缝面的目标,切缝参数仍需继续进一步优化。

Test of a Liquid Directional Roof-cutting Technology for Pressure-relief Entry Retaining Mining in Ningtiaota Coal Mine

The key technology of pressure-relief entry retaining mining (PERM) is roof directional cutting, traditional roof directional cutting adopts blasting directional cutting technology, which has many problems. The research based on the PERM project in Ningtiaota coal mine, the liquid directional roof-cutting technology test was carried out to improve the roof slicing technology. The test target required that the damage rate of rock mass between adjacent boreholes after liquid directional roof-cutting should reach above 90%, and the roof-cutting line should be a straight line, so as to ensure the roof-cutting effect in PERM project. The test system was mainly composed of pump station pressure system, abrasive supply device, cutting head conveying device, cutting head, directional device and abrasive used in field test. In the test process, four drilling holes were drilled in the roof rock layer in advance, and then cutting head was installed in the slot hole directionally through the conveying device and high-pressure sealing drill pipe. High-pressure water jet was used to make holes in the adjacent holes radially along the four slot holes, and all the slit holes were connected directionally, so as to form directional crack in the hole. The test results show that the cracks are basically straight, the maximum deflection angle of the cracks is 0~10°, but in the process of cutting seams in the four holes, the relatively intuitive cracks in the holes have not penetrated through the hole wall of the whole borehole. The results show that the liquid directional roof-cutting technology cannot achieve the goal of forming 90% of the cutting line through the design requirements of PERM, and the parameters of the liquid directional roof-cutting technology still need to be further optimized.