花岗岩试样岩爆弹射破坏过程的三维离散元模拟

发布时间：2018-03-24 10:15

本文选题：花岗岩　切入点：岩爆　出处：《广西大学》2015年硕士论文

【摘要】：岩爆是深埋地下工程岩体在人为开挖或者外界扰动的作用下产生的一种工程灾害,随着国内深埋水工隧洞及其他地下工程的增多,岩爆灾害发生的频率也日趋升高,岩爆的发生会使工程中的围岩突然向临空面发生大面积岩块弹射、抛掷等破坏现象,这将严重影响工程施工进度和威胁施工人员的安全。本文在室内花岗岩岩爆试验的基础上,采用三维离散单元软件3DEC对室内岩爆试验开展模拟研究。基于离散元软件3DEC的功能,对将进行数值模拟的完整花岗岩试样离散成大小不一的岩块单元,岩块单元之间由接触面连接,通过选取合适的材料参数和本构模型,结合软件随机给接触面赋参数功能将各接触面的力学参数随机化来满足岩石材料的非均匀性,实现室内花岗岩试样岩爆弹射破坏过程的三维离散元数值模拟。结果表明,模拟结果与试验结果基本吻合,表明了本文模拟方法的可行性,克服了以往很多采用基于连续介质的数值模拟难以模拟岩爆弹射破坏非连续变形力学行为的局限性,为研究岩爆破坏机理提供了一定的帮助。结合数值模拟对物理岩爆试验的模拟,从岩爆破坏过程中岩石内部的位移场、应力场、能量演化过程三个方面来开展相关研究。数值试验结果表明,从位移场来分析,岩石在进行单面卸载发生岩爆后,岩石块体的位移会向临空面增大,而未弹射的一些块体会发生微小的位移回弹,同时在靠近卸载面处的块体之间会发生比较大的剪切位移；从岩石内应力场来分析,岩石在卸载后,靠近临空面的岩石在岩爆破坏过程中受到张拉应力和剪切作用,表明岩爆发生过程是在拉剪共同作用的情况下产生的；从能量演化过程来分析,岩石处在未卸载前的真三轴压缩状态时岩石内部一直在聚集弹性应变能,且在弹性阶段聚集最多,岩石在进行单面卸载后,集聚在岩石内部的弹性应变能开始释放,释放的能量大约只有0.84%转换成块体的动能,其中99.16%的能量转换成耗散能,其中耗散能主要用于岩块单元间裂纹的萌生、扩展及贯通。
[Abstract]:Rock burst is a kind of engineering disaster caused by artificial excavation or external disturbance of deep buried underground engineering rock mass. With the increase of deep buried hydraulic tunnel and other underground engineering in China, the frequency of rock burst disaster is also increasing day by day. The occurrence of rock-burst will make the surrounding rock in the engineering suddenly burst into the face of the sky with a large area of rock mass ejected and thrown, which will seriously affect the construction progress of the project and threaten the safety of the constructors. Three dimensional discrete element software (3DEC) was used to simulate the rock burst test in laboratory. Based on the function of discrete element software 3DEC, the intact granite samples were discretized into blocks of different sizes. By selecting appropriate material parameters and constitutive models and combining with the function of randomly assigning parameters to the contact surface, the mechanical parameters of each contact surface are randomized to satisfy the nonuniformity of rock materials. Three-dimensional discrete element numerical simulation of rock burst and ejection failure process of granite samples in laboratory is realized. The results show that the simulation results are in good agreement with the experimental results, which indicates the feasibility of the simulation method in this paper. It overcomes the limitations of many previous numerical simulations based on continuous medium which are difficult to simulate the mechanical behavior of discontinuous deformation of rockburst ejection failure. It provides some help for studying the failure mechanism of rock burst. Combined with numerical simulation to simulate the physical rock burst test, the displacement field and stress field of rock in the process of rock burst failure are analyzed. The results of numerical experiments show that the displacement of rock mass increases to the face of the void after rock burst occurs when the rock is unloaded on one side from the displacement field. However, some blocks without ejection will have a small displacement rebound, and a relatively large shear displacement will occur between blocks near the unloading surface, and from the stress field inside the rock, the rock can be unloaded. The rock near the goaf face is subjected to tensile stress and shear action during the rock burst failure, which indicates that the rock burst occurred under the joint action of tension and shear, and analyzed from the energy evolution process. When the rock is in the true triaxial compression state before unloading, the elastic strain energy has been accumulated in the rock, and the elastic strain energy has been accumulated most in the elastic stage. The elastic strain energy accumulated in the rock begins to release after unloading on one side. Only about 0.84% of the energy released is converted into kinetic energy of the block, of which 99.16% of the energy is converted into dissipative energy. The dissipative energy is mainly used for crack initiation, propagation and penetration between rock blocks.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

【引证文献】