真三轴卸载下深部岩体破裂特性及诱发型岩爆机理研究

发布时间：2018-01-12 14:36

本文关键词：真三轴卸载下深部岩体破裂特性及诱发型岩爆机理研究　出处：《中南大学》2013年博士论文　论文类型：学位论文

【摘要】：矿山深井开采面临着众多难题,如何改善深部岩体所处的复杂力学环境——高地应力、高地温、高岩溶水压力及爆破、机械开挖等引起的动力扰动(“三高一扰动”)就是其中之一。高应力意味着高岩体储能。在工程开挖卸荷过程中,高应力岩体内的高储能被诱发释放,从而导致围岩破裂并诱发岩爆等大规模工程灾害。本文从高地应力受力环境出发,利用自行研制的岩石真三轴电液伺服诱变(扰动)试验系统,深入研究真三轴卸荷状态下高应力岩石的力学特性及动载荷诱发岩爆的可能性,揭示深部岩爆灾害的扰动诱发机理。主要研究内容及研究成果如下： (1)深部工程岩体主要受到卸荷损伤和应力调整集中的作用,利用自行设计的岩石真三轴电液伺服诱变(扰动)试验系统对不同应力状态下花岗岩、红砂岩及水泥砂浆的立方试件进行了真三轴卸载压缩破坏试验。研究结果表明卸载后二维受力下岩石的抗压强度随中间主应力的增大而增大,但增大的幅度逐渐降低。当单轴压缩或中间主应力较小时,岩石破坏模式为剪切破坏；随着中间主应力的增大,岩石的破坏模式逐渐由剪切破坏转变为板裂破坏。从本文的研究结果得出岩石发生板裂破坏不仅与岩性有关,还与其应力状态有关。 (2)基于莫尔-库伦强度准则分析了岩石破坏模式的转变。通过莫尔-库伦定律计算的不同应力水平下岩石的计算强度与花岗岩和红砂岩试件的测试强度的比较发现,测试强度值明显低于计算强度值,说明岩石破坏时强度不再符合莫尔-库伦强度准则,破坏模式由剪切破坏转变为板裂破坏。 (3)利用声发射测试系统与红外热像仪对岩石板裂破坏时的声发射数及温度变化进行了监测。通过声发射计数分析得出剪切裂纹的产生伴随着整个加载过程,而板裂裂纹不同于剪切裂纹,是在岩石受力达到一定程度时才产生。单轴压缩条件下,岩石发生剪切破坏,压缩椎体表面温度变化显著；当中间主应力较小时,岩石下半部分先发生破坏,然后再发生整体破坏,岩石破坏形式为剪切破坏；当中间主应力较大时,整个试样表面温度均有明显的升高,说明岩石的破坏形式为板裂破坏。 (4)根据地下工程开挖下岩体受力路径及板裂破坏发生条件,开展了扰动诱发岩爆试验。对真三轴卸载下试件施加扰动载荷,研究证明无论扰动载荷是垂直最大主应力方向还是沿着最大主应力方向施加,只要载荷幅值达到一定程度均可诱发岩爆破坏。根据扰动诱发岩爆试验,提出了扰动诱发岩爆结构演化模型。 (5)运用离散元PFC3D程序对扰动诱发岩爆进行了数值模拟,从微观角度分析得到了与试验结果相一致的结论。当扰动载荷的幅值为300、400、500kN时,试件内部有微裂纹扩展,但趋于稳定,岩石未发生破坏；但扰动载荷幅值为600kN时,微裂纹扩展迅速,岩石发生岩爆破坏。
[Abstract]:Deep mine mining is faced with many difficulties, how to improve the complex mechanical environment of deep rock mass-high ground stress, high ground temperature, high karst water pressure and blasting. The dynamic disturbance caused by mechanical excavation ("three high and one disturbance") is one of them. High stress means high rock mass energy storage. In this paper, based on the stress environment of high ground stress, the real triaxial electro-hydraulic servo mutagenic (disturbance) test system of rock is developed. The mechanical properties of high stress rock under true triaxial unloading state and the possibility of rock burst induced by dynamic load are studied in depth, and the disturbance inducing mechanism of deep rock burst disaster is revealed. The main research contents and results are as follows: 1) the deep engineering rock mass is mainly affected by unloading damage and stress adjustment concentration. The granite under different stress states is treated by using the self-designed true triaxial electro-hydraulic servo mutagenic (disturbance) test system. The true triaxial unloading compression failure test was carried out on the cubic specimen of red sandstone and cement mortar. The results show that the compressive strength of rock increases with the increase of intermediate principal stress after unloading. When uniaxial compression or intermediate principal stress is small, the failure mode of rock is shear failure. With the increase of intermediate principal stress, the failure mode of rock changes from shear failure to plate fracture. From the results of this paper, it is concluded that the failure of rock slabs is not only related to lithology, but also to its stress state. 2). Based on Mohr Coulomb strength criterion, the transformation of rock failure mode is analyzed. The comparison of calculated rock strength with that of granite and red sandstone specimens under different stress levels calculated by Mohr Coulomb's law is made. . The measured strength value is obviously lower than the calculated strength value, which indicates that the strength of rock is no longer in accordance with the Mohr Coulomb strength criterion, and the failure mode is changed from shear failure to plate crack failure. 3). Acoustic emission measurement system and infrared thermal imaging system are used to monitor the number of acoustic emission and the temperature change of rock slab cracking. By acoustic emission counting analysis, it is concluded that the shear crack is accompanied by the whole loading process. The crack of plate is different from the shear crack, and it only occurs when the stress of rock reaches a certain degree. Under uniaxial compression, shear failure occurs in rocks, and the surface temperature of compression vertebrae changes significantly. When the intermediate principal stress is small, the failure of the lower part of the rock occurs first, then the whole failure occurs, and the failure of the rock is in the form of shear failure. When the intermediate principal stress is larger, the surface temperature of the whole specimen increases obviously, which indicates that the failure form of rock is plate fracture. 4) according to the stress path of rock mass under excavation of underground engineering and the occurrence condition of slab crack failure, the disturbance induced rockburst test is carried out. The disturbance load is applied to the specimen under true triaxial unloading. It is proved that no matter whether the disturbance load is applied in the vertical direction of the maximum principal stress or along the direction of the maximum principal stress, the rockburst damage can be induced as long as the amplitude of the load reaches a certain degree. A model for the evolution of rock burst structure induced by disturbance is proposed. 5) numerical simulation of disturbance induced rockburst is carried out by using discrete element PFC3D program, and the results are in agreement with the experimental results from the microscopic point of view. When the amplitude of disturbance load is 300,400. At 500kN, there is a microcrack propagation inside the specimen, but it tends to be stable and the rock is not destroyed. However, when the amplitude of disturbance load is 600 KN, the microcrack grows rapidly and rock burst occurs.
【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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