岩层运动并行计算系统中动力本构模型引入和巷道冲击破裂过程模拟

Introduction of dynamic constitutive model into parallel computing system of strata motion and modeling of impact fracture process of roadway

  • 摘要: 巷道围岩的动力冲击破坏研究对于巷道冲击地压的机理分析和预防具有重要的理论和实际意义。在微机上模拟巷道冲击时,现有的国外通用商业软件的计算规模小,计算效率低,功能有限。在历时10多年自主开发的岩层运动并行计算系统中,发展了动力模拟功能,通过岩样的单轴压缩动力实验验证了该方法的正确性。具体而言,以适于较宽应变率范围的朱−王−唐动力本构模型取代静力本构模型,即广义胡克定律,以提高系统的适用性;以动态黏聚力取代摩尔−库仑准则中的静态黏聚力,以考虑岩石的动力强度特性;以黏性阻尼取代局部自适应阻尼,以克服其在模拟动力学问题时的局限性。通过在巷道围岩模型上表面施加冲击速度,考察了不同应变率条件下巷道围岩模型的失稳规律。当应变率低时,巷道围岩的失稳呈间歇性,这是因为巷道围岩的强度较低,存储的应变能较少,失稳易于发生,也易于停止,但不足以为剧烈的大失稳提供足够的动能;当应变率高时,巷道两帮的开裂区发展较快,这是由于开裂区扩展所需要的能量能得到及时供给,巷道围岩的失稳具有持续性,只有当围岩储存的应变能较高时才能失稳,一旦失稳,则难以停止,这将造成严重的动力灾害。为未来支护条件下巷道抗冲击研究奠定了良好的技术基础。

     

    Abstract: It is theoretically and practically significant to study the dynamic fracture of the roadway surrounding rock under impact for analyzing mechanisms of roadway rockbursts and for predicting and preventing them. When roadway rockbursts are modeled on the microcomputer, the foreign commercial software has small-scale computing capacity, low computing efficiency, and limited applicability. In the present paper, based on the parallel computing system of the strata motion developed by us in the past ten years, the dynamic modeling ability is developed. The present method is validated through modeling the dynamic tests for rock specimens in uniaxial compression. The static constitutive model (the Hooke’s law) is replaced by the Zhu-Wang-Tang dynamic constitutive model applicable in a wide range of strain rates. The static cohesion in the Mohr-Coulomb criteria is replaced by the dynamic cohesion to consider the dynamic strength of rock. The local adaptive dumping leading to over damping in the dynamic modeling is replaced by the viscous dumping. The model composed of a roadway and its surrounding rock is impacted at the top of the model in the form of the constant velocity. Effects of the velocity on the instability of the model are investigated. At low strain rates, the instability of the model exhibits intermittent characteristics, which is due to the fact that the strength of the surrounding rock is low and few strain energy is stored. Thus, instability begins and ends easily, but no kinetic enough is provided for a serious large instability. However, at high strain rates, the development of the cracking regions at two sides of the roadway is very rapid, which is due to the fact that the need energy can be provided timely. Thus, the instability is continuous. When the stored strain energy is high, the instability takes place and ending is difficult, resulting in a serious dynamic hazard. The present work provides a good technical base for the study on the anti-impact of the roadway under support in the future.

     

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