柱面波叠加成平面波的传播规律与锚杆响应特征的数值试验研究

Numerical test study on propagation law of cylindrical wave superimposed into plane wave and response characteristics of rockbolts

  • 摘要: 为了再现爆炸柱面波能够通过相互叠加而形成平面波的可视化过程及其传播规律,以室内模型试验结果为参考依据,借助非线性显式动力分析软件,开展了柱面波叠加成平面波并与锚固硐室围岩相互作用的数值试验研究。分析了平面波在岩体中的传播规律,比较了毛硐和锚固硐室围岩中动态裂纹的分布规律,探讨了锚杆对平面波的响应特征,并与相应模型试验结果进行了对比分析。结果表明,柱状装药爆炸后形成的柱面波能够通过相互叠加而在装药平面上、下方形成平面波,传播到模型上表面和硐室拱顶时都被反射产生了拉伸波,这两处都产生了拉伸裂纹;毛硐与锚固硐室附近围岩的裂纹分布形态基本相同,只是毛硐的拱脚部位裂纹分布宽度比锚固硐室的略大一些;锚杆中部应变峰值比其端部和根部的大,且其整体以受拉变形为主,这与锚杆提高围岩抗拉强度的作用相符合;锚杆端部受围岩的约束作用较小而导致其拉压比约为根部的3.2倍。将模拟得到的锚杆轴向应变波形曲线同模型试验的相应曲线进行了比较,发现2者在变化趋势方面的一致性较好,实测轴向应变波形曲线受压、受拉段的时长约是其相应模拟波形曲线的2倍,且实测轴向应变峰值也比与其相对应的模拟的大。可以通过柱面波叠加的方式形成平面波,从而获得开展模型试验与数值试验所需要的平面波动荷载。

     

    Abstract: In order to reproduce the visualization process and propagation laws of plane waves formed by the superposition of explosive cylindrical waves, with reference to the results of the indoor model test as a reference basis, a numerical test was carried out to investigate the interaction between the superposition of explosive cylindrical waves and the surrounding rock of the anchorage cavern with the help of nonlinear explicit dynamic analysis software. The propagation law of plane wave in the rock mass was analyzed, the distribution characteristics of dynamic cracks in the surrounding rock of unreinforced and anchorage caverns were compared, and the response laws of the rockbolts to the plane wave were discussed and analyzed in comparison with the results of the corresponding model tests. The results showed that the cylindrical waves formed after the explosion of the cylindrical charge by superimposing on each other were able to form plane waves above and below the charge plane and were reflected to produce tensile waves when they propagated to the upper surface of the model and to the vault of the caverns, and tensile cracks were produced in both places. The cracks distribution patterns near the surrounding rock of the unreinforced cavern anchorage cavern were basically the same, except that the width of crack distribution at the arch foot of unreinforced cavern was slightly larger than that of the reinforced cavern. The strain peak in the middle of the anchor rod was larger than that of its ends and roots, and the overall deformation is mainly in tension, which was consistent with the roles of the rockbolts in improving the tensile strength of the surrounding rock. The rockbolts’ end was less constrained by the surrounding rock resulting in a tension-compression ratio of approximately 3.2 times that of the root. The simulated axial strain waveform curves of the rockbolts were compared with the corresponding curves of the model tests’, and it was found that both of them had better consistency in the trend of change, and the lengths of the measured axial strain waveform curves of the compression and tensile segments were about twice as long as those of their corresponding simulated waveform curves, and the peak values of the measured axial strain were also larger than those of their corresponding simulation. It is known that plane waves can be formed by superposition of cylindrical waves to obtain the plane wave loads required to carry out model tests and numerical tests.

     

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