锚杆−泡沫铝联合支护锚固体单轴压缩声发射特征试验研究

    Experimental study on acoustic emission characteristics of anchor body by bolt-foam aluminum combined support under uniaxial compression

    • 摘要: 为了研究锚杆−泡沫铝联合支护冲击地压巷道的支护机制,对不同锚杆数量和泡沫铝厚度的8种锚杆−泡沫铝联合支护锚固体进行了单轴压缩试验,研究了不同支护参数下锚固体的力学特性及破坏机理。通过在单轴压缩过程中不同支护参数下锚固体声发射信号中提取与冲击地压有关的声发射特征值,研究了锚固体声发射特征值的演化规律以及与支护参数、试样力学参数、试样冲击倾向性参数的关联性。结果表明:泡沫铝能够提高锚固体的强度和韧性,提高系统弹性能耗散能力,减少系统内以机械能形式释放的弹性能,进而提高锚固体抵抗冲击破坏的能力;声发射振铃计数与能量演化呈现3阶段特征,其中缓慢上升阶段时长占比与泡沫铝厚度呈正相关关系,且破坏时未出现传统支护的“垂直式增长”现象,表明泡沫铝通过刚度强化和大变形吸能可有效抑制能量突变;建立了声发射参数与力学参数、支护参数、冲击倾向性参数的定量关系模型;声发射b值演化呈现3阶段特征,临近破坏时的b值大小与泡沫铝厚度呈线性正相关关系,当泡沫铝厚度为5、10、15、20 mm时,b值分别为0.069 07、0.081 15、0.089 67、0.100 25。

       

      Abstract: In order to study the supporting mechanism of rock burst roadway supported by rock bolt-foamed aluminum, uniaxial compression tests were carried out on eight kinds of rock bolt-foamed aluminum combined supporting anchors with different anchor numbers and foamed aluminum thickness conditions, and the mechanical properties and failure mechanism of the anchors under different supporting parameters were studied. By extract that acoustic emission characteristic values relate to the rock burst from the acoustic emission signals of the anchored body under different support parameters in the uniaxial compression process, the evolution law of the acoustic emission characteristic values of the anchored body and the correlation between the acoustic emission characteristic values and the support parameters, the mechanical parameters of the sample and the parameters of the rock burst tendency of the sample are studied. The results show that aluminum foam can improve the strength and toughness of the anchor body, improve the elastic energy dissipation capacity of the system, reduce the elastic energy released in the form of mechanical energy in the system, and then improve the ability of the anchor body to resist impact damage; the acoustic emission in count and energy evolution present three-stage characteristics, in which the time proportion of the slow rising stage is positively correlated with the thickness of the foamed aluminum, and the phenomenon of “vertical growth” of the traditional support does not appear during the failure, which indicates that the foamed aluminum can effectively restrain the energy mutation by strengthening the rigidity and absorbing energy through large deformation. A quantitative relationship model was established between the acoustic emission parameters and the mechanical parameters, support parameters, and impact tendency parameters. The evolution of the acoustic emission b-value shows three-stage characteristics. The size of the b-value near the failure is linearly correlated with the thickness of the foam aluminum. When the thickness of the foam aluminum is 5, 10, 15, and 20 mm, the b-values are 0.069 07, 0.081 15, 0.089 67, and 0.100 25, respectively.

       

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