长大隧道岩爆灾害的岩石动力学机理及其控制

【作者】 黄锋；

【导师】 徐则民；

【作者基本信息】 昆明理工大学 ， 道路与铁道工程， 2007， 硕士

【摘要】 本文首先概述了岩爆研究的现状，然后以弹性动力学理论为基础，借助动态光弹性实验和有限元数值模拟手段，以探求岩爆的岩石动力学机理和相对应的岩爆控制方法为日的，取得了以下几个方面的成果：(1)分析了岩石静力学理论在岩爆研究中的具体应用，以及在解释若干岩爆现象和指导岩爆预测及控制上存在的局限性，指出探求岩爆灾害的岩石动力学机理的必要性和迫切性。(2)弹性动力学理论的分析表明，隧道爆破对当前炮次围岩的扰动主要以冲击波为主，在达到爆破破岩的同时，当前炮次围岩内也形成了大最损伤裂缝：对既有炮次围岩的扰动以弹性波为主，适合用经典的“Lamb点(或线)源问题”来分析，爆破产生的应力波中，对岩爆形成有突出贡献的是压缩P波和表面Rayleigh波，其致裂作用和传播规律是岩爆发生的重要因素之一。(3)利用Ansys有限元分析软件，研究了自重和爆破荷载共同作用下，隧道围岩的响应问题。静力分析结果表明：在自重应力场作用下，隧道轮廓面周围出现了明显的应力恶化现象，基本满足弹性解析，但仍远小于围岩的破坏强度，发生岩爆的可能性很小。动力分析结果表明：在爆炸应力波的扰动下，围岩应力和位移均发生了明显的波动，最大振幅是平衡状态下的数倍，可导致围岩受拉和剪切破坏，这与岩爆的微观破裂机制一致，应力集中最大处距离掌子面约1倍洞径，这很好满足了岩爆与爆破间的空间关系，强扰动带的深度约为1倍Rayleigh波波长，表明Rayleigh波对围岩扰动的控制性作用。(4)动态光弹性实验方面，Lamb线源问题的模拟实验表明：模型表面倾斜加载时，模型内传播了P波、S波和Rayleigh波，三种应力波相互作用，在模型中上部位形成较大应力集中；岩爆追踪现象(Lamb点源问题)的模拟实验表明：平行模型表面加载时，模型内仅传播了P波，说明岩爆事件本身对母岩的冲击扰动，主要以P波扰动为主；横向切槽的模拟实验表明：横向切槽对于Rayleigh波，可以实现大部分的拦截，对于P波，主要是延长了应力波的作用时间，减缓了爆破能量的传递。(5)综合弹性动力学理论的分析以及数值试验和动光弹实验的结果可知，P波和Rayleigh波的致裂作用和传播规律是岩爆发生的重要因素之一，一次或多次的动力扰动是岩爆发生的必要条件，而非简单的高地应力下的激发作用，完整的岩爆机理应该是“完整硬脆性岩体+较高地应力+(一次或多次)动力干扰”。更多还原

【Abstract】 First of all, the research actualities of rock burst are summarized in thetext. And then, the rock dynamics mechanism and related controllingmethod are discussed on the base of elastic dynamics, by thephoto-elasticity and finite element methods. The followed results areobtained:(1) After analyzing the applications of rock statics in rock burstresearch, the localizations of statics in expressing some importantphenomena and instructing control and prediction. There are imminence andneed of rock dynamics mechanisms.(2) The analyses of elastic dynamics theory show: the excavatingsurrounding rocks are mainly disturbed by shock waves, and formed a lot ofcrack while blasting excavation. The excavated surrounding rocks aremainly disturbed by elastic waves, which is suitable for Lamb problem. ThePress and Rayleigh have great contributions to the forming of rock burst.Their fracturing and propagation rules are very important to rock burstforming.(3) The responses of surrounding rocks under gravity and blastingwaves are studied by Ansys finite element programme. The results of staticsanalyses show: the stresses of rocks around tunnel surface are depravedunder gravity of itself, which meets elastic mechanics approximately. Butthese stresses are far from the intensity, so rock burst hardly happen. Theresults of dynamics analyses show: surrounding rocks’ stresses and strainsalso fluctuate acutely, which can bring on rocks’ tensile or shear failure.The violent disturbances locate about in the depth of 1 time Rayleigh wavelength and 1 time tunnel diameter to blasting face, which proves the spacerelation between rock burst and blasting, and the importance of Rayleighwave to rock burst’s forming.(4) About the experiment of photo-elastic, the simulation of Lamb lineload show: when the direction of load inclines the surface of mode, there will be Press wave, Shock wave and Rayleigh wave, which form stressconverges in the middle top of mode plane. The simulation of rock trackingshow: when the direction of load parallels the surface of mode, there willonly be Press wave, which proves that the disturbances from rock burstfragments are mainly contributed to Press waves, the simulation of slotshow: Slot across the face of mode plane can head off mass of Rayleighwave and prolong the time of press wave action to delay the transfer ofexploding energy.(5) By integrating the 3 results of elastic dynamic theory, finiteelement analyses and photo-elastic experiment, the conclusion can besummarized that: the propagation and fracturing rules of Press wave andRayleigh wave are important rock burst forming factors. One or moredynamic disturbances are necessary conditions of rock burst forming. Thecomplete mechanisms of rock burst should be "complete hard brittle rockmass+higher ground stress+dynamic disturbances".更多还原