裂隙煤岩动态破裂行为与冲击失稳机制研究

发布时间：2018-04-04 09:49

  本文选题：冲击地压　切入点：裂隙煤岩　出处：《中国矿业大学》2017年博士论文

【摘要】：冲击地压是一种复杂的煤岩动力灾害,严重威胁着矿井的安全高效开采。随着矿井开采深度和强度的增加,冲击地压灾害愈发严重。煤岩体含有不同种类及大小的裂隙结构面,煤岩冲击失稳是裂隙煤岩体裂纹扩展贯通的结果。基于此,本文紧紧围绕裂隙煤岩动态破裂行为和冲击失稳机制,采用实验测试、理论分析和现场试验等方法,研究裂隙煤岩体受载条件下的动态失稳特征及准则;建立考虑结构面的冲击地压模型,揭示共振效应及地震波扰动对煤岩体冲击失稳的影响,分析现场实测冲击地压演化过程能量场及微震波形的动态特征。论文得到了如下主要成果:实验测试了裂隙煤岩加载破坏的力学特征,结果表明,随预制裂纹倾角的增大,应力峰值、弹性模量和应变能均呈先减小后增大的趋势;随着孔洞直径的增加,应力峰值、弹性模量和应变能均逐渐降低,但降低幅度减小。预制裂纹倾角较小时,裂纹在孔洞周边起裂,倾角较大时在预制裂纹尖端起裂,宏观破坏均发生在二次起裂的裂纹贯通处。基于弹塑性力学和损伤力学等建立了考虑裂隙压密闭合效应的统计损伤本构模型,建立了裂纹的起裂准则,分析了正应力和切应力的时变演化特征。裂隙煤岩单轴加载过程中释放的累计声发射能量和应变能符合by(28)ax形式的幂函数关系。临近失稳破坏时声发射长程相关性增强,多重分形参数增大;声发射波形频率降低,幅值增高,低频带小波包能量增加,低频IMF分量所占能量增加,Hilbert瞬时能量增大。基于裂隙煤岩动态破裂行为和声发射信号非线性特征研究结果,提出了裂隙煤岩坚固体断裂自组织扰动失稳机制,并通过裂隙煤岩的动态破裂特征及声发射参数进行了验证。建立了考虑结构面效应的裂隙煤岩弹塑脆性突变模型,引入体能势函数的概念,研究了煤岩动态变形破裂过程中能量积聚与耗散的联系,得到了冲击地压发生的能量条件,建立了“体元-区域-系统”冲击地压模型,揭示了冲击地压的动态演化过程。在外界扰动或高应力状态下,系统某区域内体元失稳后迅速向邻近体元释放能量,当该能量和邻近体元原始能量之和达到邻近体元的承受阈值后,邻近体元失稳并释放能量形成“连锁”反应,造成局部区域失稳,最终导致系统失稳,发生冲击地压。基于结构动力学理论,从共振角度分析了地震波对含结构面煤岩体冲击失稳的影响,共振作用的放大倍数与频率比呈对称分布,随阻尼比减小呈幂函数增加。研究了地震波对煤岩体冲击扰动失稳破坏的响应机制,扰动能量大,参与冲击地压过程的煤岩体较多,破坏范围较大;扰动能量小,参与冲击的煤岩体较少,破坏范围较小。研究了冲击地压演化过程中能量场及微震波形的动态演化特征。结果表明,能量场处于动态调整状态并向震源区集聚;临近冲击失稳时煤岩破裂从小尺寸串级过渡到大尺寸串级,统计涨落愈来愈大,释放能量增多,微震波形幅值增大,低频成分增多,主频率降低,波形的相似度及关联性也越来越大,波形能量向低频集聚。本研究成果对于深入认识冲击地压机理和前兆规律,开展更加有效的监测预警,促进冲击地压等煤岩动力灾害更加科学合理的防治具有重要的理论意义和应用价值。
[Abstract]:Rockburst is a kind of complex coal rock dynamic disasters, a serious threat to the mine safety and efficient mining. With the increase of mining depth and intensity of rockburst disaster is more serious. The fissure structural plane of coal and rock with different shapes and sizes, rockburst instability crack rock fracture propagation. Based on the results of coal this, the article focuses on the fracture of coal rock dynamic fracture behavior and impact failure mechanism, the experimental test, theoretical analysis and field test, the research of fractured coal rock under dynamic load conditions the instability characteristics and standards; establish the model of rockburst considering structure, reveal the resonance effect and seismic wave disturbance instability effect of coal and rock impact, dynamic characteristic analysis of the evolution process of the energy field and wave field microseismic rockburst. The main results are as follows: the test of the coal rock and fissure Mechanical characteristics, load the results show that with increasing angle crack, peak stress, elastic modulus and strain energy were first decreased and then increased; with the increase of the pore diameter, peak stress, elastic modulus and strain energy are gradually decreased, but the decrease is reduced. Crack is small angle, cracks in the holes surrounding the crack, crack in prefabricated crack tip angle large, macroscopic failure occurred in two times the initiation of crack coalescence. The elastic-plastic mechanics and damage mechanics, damage constitutive model is established based on statistical damage fracture pressure closed effect consideration, established the criterion of cracks analysis, normal stress and shear stress of time-varying evolution. Fracture of coal rock uniaxial loading process in the release of the cumulative AE energy and strain energy with by (28) ax in the form of power function relationship. Near the failure of long-range correlation by acoustic emission Strong increase of multifractal parameters; acoustic emission waveform frequency decreases, the amplitude increased, low frequency band of wavelet packet energy increases, the low frequency IMF component for energy increases, Hilbert instantaneous energy increases. The fractures of coal rock dynamic fracture behavior of the acoustic emission signal the nonlinear characteristics of coal rock fracture based on solid fracture self organization disturbance instability mechanism is put forward and, through the dynamic fracture of coal rock burst characteristics and acoustic emission parameters were verified. By considering the effect of the surface structure of coal rock elastoplastic brittle fracture catastrophe model, introducing the concept of physical potential function, the research of the coal and rock dynamic deformation accumulation and dissipation of energy in the process of rupture, the impact of energy conditions the rock burst occurrence, established the rockburst model element - regional - system ", reveals the dynamic evolution process of rockburst. The external disturbance or in high stress state, a regional system The inner body element failure quickly to the adjacent element when the release of energy, energy and energy of the original element near the body and reach the threshold under adjacent voxels, the adjacent element instability and energy release form a "chain" reaction caused by local instability, resulting in system instability, occurrence of rockburst. Based on the theory of structural dynamics, from the point of view of the resonance of seismic wave on the impact of coal and rock with structural plane instability, resonance magnification and frequency ratio is symmetrical, with the damping ratio decreases exponentially increase. On the seismic wave on the coal and rock impact failure disturbed response mechanism failure, disturbance high energy, more coal and rock in rockburst process, damage range is large; the disturbance energy is small, less involved in the coal and rock impact failure, a smaller range. The dynamic evolution field and seismic waveform of rockburst in the evolution process Feature. The results show that the energy field in the dynamic adjustment and agglomeration to source region; near the shock instability of coal rock burst from small size to large size transition cascade cascade, statistical fluctuation is more and more big, the release of energy increased, microseismic wave amplitude increases, the low-frequency components increased, frequency decreased, and correlation of waveform similarity more and more, to the low frequency wave energy concentration. The results of this study for understanding the mechanism of rockburst and the precursory characteristics, to carry out more effective monitoring and early warning, promotion has important theoretical significance and application value of rockburst, coal rock dynamic disasters more scientific and reasonable prevention.

【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD324
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本文编号：1709427