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针对巷(隧)道岩爆破裂演化及锚杆锚固机制研究的不足,利用自制的真三轴加卸载试验系统开展具有岩爆倾向性的无锚固和树脂锚杆锚固长方体硬岩试样在单面约束情况下的双轴压缩对比试验研究,分析和探讨硬岩层爆、层级破裂演化及锚杆锚固机制。结果表明,在无锚固的情况下,硬岩呈现明显层爆现象,从临空面到深部,爆裂破断面的分形维数主要集中在1.3~1.8范围,随层序由于破断面摩擦作用的增强导致其分形维数随之降低,断裂形态随层序逐渐由张拉断裂为主导向剪切断裂为主导过渡,同时各层面均或多或少伴有次生层断裂;锚杆锚固明显降低了爆裂层数及范围,限制了硬岩逐层爆裂;理论分析得出临空面附近硬岩层爆层数的计算公式;视硬岩层爆部分为层状岩层,提出层爆控制的锚杆组合梁理论;临空面附近以劈裂为主的层爆是受压致拉的结果,通过锚杆锚固显著提高了完整岩体的抗拉强度,使层爆层数及范围大为降低甚至不发生层爆。
In order to solve the problem of rockburst evolution and bolt anchoring mechanism in alley tunnel, the self-made true triaxial unloading test system was used to develop the unchored and resin-anchored cuboid rigid rock samples with rock burst tendency Biaxial compression contrast test under the condition of surface restraint, analyze and discuss the hard rock burst, the evolution of the level fracture and the anchoring mechanism of the anchor. The results show that in the absence of anchorage, the hard rock shows obvious detonation phenomenon. The fractal dimension of the burst fracture surface mainly lies in the range of 1.3-1.8 from the frontovial plane to the deep, and as the sequence increases due to the frictional effect of the fractured surface Which leads to the decrease of fractal dimension. The fracture morphology gradually changes from the tension fracture to the shear fracture-dominant transition, and more or less the secondary fracture occurs at all levels. The anchor bolt anchorage is obviously reduced The number and range of burst layers have limited the layer-by-layer bursting of hard rock; the formula for calculating the number of hard layers in the vicinity of the apron surface has been obtained by theoretical analysis; the layer of rock- Theory; the detonation layer-based detonation near the temporary empty surface is the result of pressure-induced pull-in, and the tensile strength of the intact rock mass is significantly increased by the anchoring of the rock bolt, so that the number and range of detonation layers are greatly reduced or even not occur Layer burst.