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侏罗系地层巷道淋水顶板破坏机理及治理研究

Study on damage mechanism and treatment of water sprayed roof in Jurassic stratum roadway

  • 摘要: 我国西部侏罗系主采煤层顶板普遍赋存低层位弱富水层,导致巷道顶板尤其是顶板锚索孔长时间淋水,降低顶板围岩强度和顶板支护效果,影响矿井煤巷顶板安全。为了研究淋水顶板破坏机理及治理措施,以内蒙古双欣矿业杨家村煤矿414106辅助运输巷淋水区为研究对象,通过现场调研和顶板钻孔取样可知,向斜区巷道顶板4 m以上区域存在明显导水裂隙,锚索孔流水呈线性淋水状态,顶板围岩弯离层程度大,部分锚索锚固段脱离围岩失效。矿物成分分析和水理试验表明,顶板砂质泥岩的黏土矿物中高岭石含量高达73%,软化系数为0.162,具有明显的遇水软化特性。淋水区巷道顶板围岩初期以静水压力破坏为主,遇水软化特性降低了裂隙结构面的力学性能,在静水压力作用下围岩裂隙的尺寸剪性扩张;后期以动水压力破坏为主,主要表现为裂隙结构面变形扩展、裂隙充填物位移、管涌等,顶板围岩破坏速度也逐步加快。结合巷道淋水顶板围岩由矿压显现变形和裂隙软化扩张发展到管涌冲刷破坏的全过程分析,按照顶板钻孔围岩破坏主要形式(物理软化、渗流破坏、吸蚀扩容破坏、冲刷变形破坏)划分为4个不同阶段,形成了以顶板钻孔围岩破坏主要形式、顶板锚索孔流水状态、顶板围岩裂隙发育特征和治水加固原则为关键指标的巷道淋水顶板破坏发展阶段判定准则。结合现场条件,确定了414106运输巷淋水区为淋水顶板破坏发展第Ⅲ阶段,提出了淋水区巷道顶板锚索封孔注浆(疏水)结构形式和“深孔疏水+浅部封水+深部加固+高预应力支护”原则,制定了淋水区巷道顶板高预紧力长锚索补强与封孔注浆相结合的锚封注一体化补强方案,通过现场工业性试验和矿压监测可知,达到顶板治水和围岩加固的效果。

     

    Abstract: The roof of the Jurassic main coal seam in western China generally contained low level weak rich water layer, which led to the long-term watering of the roof of the coal roadway especially the roof anchor cable hole and the reduction of the roof surrounding rock strength and the roof support effect, and affected the safety of the coal roadway roof. In order to study the damage mechanism and control measures of the water sprayed roof, the No.414106 auxiliary transportation water spraying area of Yangjiacun Coal Mine of Shuangxin Mining in Inner Mongolia was taken as the research object. Through field investigation and roof drilling sampling, it could be seen that there were obvious water conducting cracks in the area 4m above the roof of the roadway in the synclinal area. The water flowing from the anchor cable hole was in a linear water spraying state. The roof surrounding rock had a large degree of deflection, and some anchor cable anchorage sections were separated from the surrounding rock. The mineral composition analysis and water physical test showed that the clay minerals in the roof sandy mudstone contain up to 73% kaolinite, and the softening coefficient is 0.162, which had obvious water softening characteristics. At the initial stage, the roof of the coal roadway in the water spraying area was mainly destroyed by hydrostatic pressure, and the water softening property reduced the mechanical properties of the fracture structural plane, which led to the expansion of the size of the surrounding rock fractures in shear under the action of hydrostatic pressure. In the later stage, the roof surrounding rock was mainly destroyed by hydrodynamic pressure, which was mainly manifested in the deformation and expansion of fracture structural plane, displacement of fracture fillings, piping, etc. The destruction speed of roof surrounding rock was gradually accelerated. The whole process of surrounding rock of water drenching roadway roof from ground pressure appearance deformation and crack softening expansion to piping corrosion failure was analyzed. According to the main forms of the surrounding rock failure of roof drilling (physical softening, seepage failure, suction corrosion expansion failure, scouring deformation failure), it was divided into four different stages. The criteria for determining the development stage of roof failure of roadway drenching water had been formed with the main forms of roof drilling surrounding rock failure, the flow state of the roof anchor cable hole, roof surrounding rock fracture development characteristics and water control reinforcement principles as the key indicators. Combined with the site conditions, the 414106 auxiliary transportation water spraying area was the Ⅲ stage of the development of spraying roof damage. The structural form of anchor cable sealing grouting (drainage) and the principle of “deep hole drainage + shallow water sealing + deep reinforcement + high pressures support” were proposed for the roof of the roadway in the spraying area. An integrated reinforcement scheme of anchoring, sealing and grouting, which combined the reinforcement of high pre-tightened long anchor cables and sealing and grouting on the roof of the roadway in the water-spraying area, had been formulated. According to the field industrial test and rock pressure monitoring, the effect of roof water control and surrounding rock reinforcement was achieved.

     

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