基于格栅拱架的软岩巷道分步联合控制技术研究

Step by step and combined supporting technique with steel grid frame for soft and fractured rock roadway

针对煤矿深井软岩巷道大变形灾害频发难题,以淮南矿区潘三矿软岩大变形巷道为工程背景,在系统分析围岩失稳破坏大变形原因的基础上,提出了深部软弱破碎巷道基于格栅拱架的分步联合支护技术,包括:格栅支架+一次锚杆锚索、初喷、浅孔注浆、预应力锚杆、复喷150 mm厚混凝土、深孔注浆和帮顶预应力锚索。进一步,分析了格栅拱架支护控制原理,并采用FLAC^(3D)确定了基于格栅拱架的分步联合技术的最优支护参数。现场对比分析表明,格栅拱架支护围岩初期变形速率及最终收敛变形量均大于型钢支护,但加设二次支护之后格栅拱架位移能较快收敛,此外,格栅支护在经济和效率方面优于钢拱架支护。最后,通过现场监测,格栅拱架分步联合技术各工序的最优施工周期为:预应力锚杆、锚索合理的支护时间是注浆后10 d内,而深孔注浆之后预应力锚杆2周内较优。实践表明,基于格栅拱架的分步联合控制技术深井是软岩巷道围岩控制的一条有效途径。

Aiming at the difficult problems of the large deformation in deep and soft rock roadways,the reasons of large deformation are first analyzed for roadways in Panshan coal mine,Huainan,China.On this basis,step by step and combined supporting technique with steel grid frame for soft and fractured rock roadway,including steel grid+primary bolt and cable,initial shotcrete,shallow grouting,pre-stressed bolts,further shotcrete with thickness of 150 mm,deep grouting,and pre-stressed cables,was proposed for deep weak and fractured rock roadway.Furthermore,the control principle of grid arch support is analyzed,and the optimal support parameters(diameter of steel is 20 mm and space between frames is 700 mm)are determined by FLAC^(3D).The comparative analysis shows that both of the initial deformation rate and final convergence deformation of the steel grid technique are larger than that of the steel support,however,the roadway deformation can quickly converge after the addition of the secondary support was applied.The monitoring results showed that the reasonable period for applying pre-stressed bolt/cable is after about 10 days of shallow/deep grouting.The time between pre-stressed bolt and deep grouting that is set as 2 weeks will be better.Therefore,step by step and combined supporting technique with steel grid frame proposed here can provide an effective method for the soft rock roadway control in deep and soft coal mines.