【作者】 赵洪宝；

【导师】 尹光志；

【作者基本信息】 重庆大学 ， 矿业工程， 2009， 博士

【摘要】 含瓦斯煤失稳破坏和煤与瓦斯突出是煤矿开采过程中急需解决的关键问题。本文自行研制和开发了煤岩三轴蠕变瓦斯渗流装置及煤与瓦斯突出模拟试验系统,并利用该试验装置和系统对煤样、含瓦斯煤样在单轴和三轴压缩、循环载荷、蠕变作用下的失稳破坏规律、声发射特性以及煤与瓦斯突出进行了理论与实验研究,取得了如下主要研究成果:1.自行研制开发了煤岩三轴蠕变瓦斯渗流装置和大型煤与瓦斯突出模拟试验系统。2.为了研究含瓦斯煤样的力学特性对应力、应力途径的敏感性,进行了不同应力水平、加载方式下的实验。试验结果表明,含瓦斯煤样的力学性质具有较强的应力敏感性,同时瓦斯的存在使煤样材料变形表现出明显的延性和非线性。3.通过对煤样、含瓦斯煤样的三轴压缩和蠕变试验研究,建立了煤样在三轴压缩状态下的“四段式”本构模型、蠕变状态本构方程及含瓦斯煤样在三轴压缩状态下的改进内时本构模型、改进西原蠕变本构模型,提出了“次级滞回曲线”的概念。4.进行了不同应力状态及加载方式下煤样、含瓦斯煤样受载过程的声发射特性实验研究,得到了煤样、含瓦斯煤样失稳破坏过程的声发射特性。结果表明:单轴压缩状态下煤样的声发射事件特性曲线与全应力应变曲线吻合较好,而三轴压缩状态下声发射事件特性曲线具有明显“滞后性”,且呈“双峰”形;由于瓦斯的存在,含瓦斯煤样在三轴压缩状态下声发射事件特性曲线明显变缓,且呈“三峰”形。5.运用RFPA软件对煤样受载过程声发射特性进行了模拟研究。结合实验研究结果,建立了以声发射特性及损伤力学理论为基础的煤样损伤本构方程,以煤样声发射事件率、声发射能量数两个参数确定了煤样的损伤参数。6.根据对不同颗粒组成的两种煤样试件的力学特性、声发射特性的试验研究结果,提出了煤样力学性质的“粒度效应”。7.在煤样和含瓦斯煤样失稳破坏过程声发射特性实验室研究的基础上,结合非线性理论,研究了煤样、含瓦斯煤样失稳破坏过程声发射特性的非线性特征,分析了其自相似系数、分形维数及自组织演化规律,并建立了消去声发射信号传播速度的一维、二维声发射源定位方法。8.在煤样及含瓦斯煤样失稳破坏力学试验和声发射特性试验的基础上,结合灰色理论和突变理论,建立了含瓦斯煤样失稳破坏的灰色-突变模型,并运用该模型对含瓦斯煤样失稳破坏进行了预测。结果表明该模型精确度较高。9.对煤样三维应力状态下全应力-应变过程中瓦斯流动速度与应力耦合关系研究表明:固定围压时,轴压和瓦斯流动速度耦合关系可用四次曲线表征,且峰后煤样内瓦斯流动速度要大于煤样起始瓦斯流动速度;固定轴压时,围压和瓦斯流动速度耦合关系可用二次曲线表示;瓦斯压力对煤样峰前瓦斯流动的影响明显大于对峰后瓦斯流动的影响;不同粒径组成煤样内的瓦斯流动速度受应力影响随着粒径增加而减小,同一外界条件下时,大颗粒组成的试件内瓦斯流动速度明显大于小颗粒组成试件内的瓦斯流动速度;提出了瓦斯流动困难应力点的概念;根据流固耦合的基本理论,建立了瓦斯流动方程。10.自行研制开发了煤与瓦斯突出模拟试验系统,并进行了该实验系统的可靠性验证实验和不同地应力条件、不同煤体含水率条件下煤与瓦斯突出模拟试验研究,结果表明:该试验系统可以实现加载方式多样化、突出模具大型化、突出口开关瞬间化、充气形式平面化、记录过程动态化且精度较高、可重复性好的特点;并且得出了突出强度与含水率的关系可用二阶曲线表示、与主地应力呈修正对数关系的结论。更多还原

【Abstract】 Both unstable failure of coal contained gas and the coal and gas outburst are key problems in the process of coal mining. In this paper, triaxial gas seepage - creep of coal and Simulation Testing System of coal and gas burst are self-developed, and both the theoretical and experimental study on the unstable failure and AE laws under uniaxial compression, triaxial compression, cyclic loading, creep of coal or coal contained gas and simulation of coal and gas outburst were done, the Main research results as follows:1. Test equipment of triaxial gas seepage - creep and Simulation Testing System of coal and gas burst are self-developed.2. In order to investigate both the stress and stress paths-dependent of mechanical properties of coal contained gas, the experiment under different stress level and loading path are done. The results of experiment show: bigger stress sensitivity is had by mechanical properties of coal contained gas, and the obvious ductility and nonlinear characteristics are showed by coal because the gas exist.3. Based on experiments of triaxial compression and creep of coal and coal contained gas, both Four-section constitutive model under triaxial compression and creep constitutive model of coal and intrinsic time constitutive model under triaxial compressionand creep have improved K-B constitutive model of coal contained gas;the conception of secondary hysteretic curve is proposed.4. Experiments of AE in process of deformation under different stress and loading method of coal and coal contained gas are done and their characteristics are obtained. The results show: the characteristic curve of AE under uniaxial compression is similar to complete stress-strain curve of coal, hysteretic nature and double peak form are the obvious characteristic of the curve of AE under triaxial compression; the AE characteristic curve of coal contained gas under triaxial compression becomes gentle and present three peak form because of the existing of gas.5. AE characteristic of coal in process of deformation is simulated by the soft of RFPA. Based on results, damage constitutive equation of coal is built based on AE characteristic and damage mechanics theory, damage parameters are obtained according to event rate and energy of AE. 6.Based on experiments of mechanical properties, acoustic emission characteristics and results of sem study, effect of particle size are built.7. Based on the laboratory studies of AE in process of deforming coal contained gas and nonlinear theory, the nonlinear characteristic of AE in process of instability of coal contained gas is analyzed, the laws of Self-Similar parameter, fractal dimension, self-organization evolution are analyzed, the way of AE source location in which the velocity of AE signal is eliminated is built on one-dimensional and two- dimensional.8. Based on the laboratory studies of mechanical properties and AE in process of deforming coal or coal contained gas, grey-catastrophe model that is used to predict and judge the instability of coal contained gas is built according to grey theory and catastrophe theory, the result of predict and judge the instability of coal contained gas show by the model: the accuracy is higher.9. The result of coupling relationship between velocity of gas seepage and stress in process of whole deformation under three-dimensional stress shows: quartic curve expresses the coupling relationship between velocity of gas seepage and axial pressure under fixed confining pressure very well, and the velocity after instability of coal contained gas is bigger than before ; quadratic curve expresses the coupling relationship between velocity of gas seepage and confining pressure under fixed axial pressure;the effect on velocity of gas seepage caused by gas pressure before instability of coal contained gas is obviously bigger than after it; the effect on velocity of gas seepage of coal sample composed of different diameter coal particle decreases as diameter coal particle increase, the velocity of gas seepage of coal sample composed of big diameter coal particle is obviously bigger than small it under same conditions, and the conception of difficulty stress point of gas seepage is the gas seepage equation model is built based on fluid-solid coupling theory.10. Simulation Testing System of coal and gas burst is self-developed, and the experiments of coal and gas burst under same conditions or different ground stress and moisture content of coal are done, the results show: the characteristics which include diversification of loading mode, large-scale of outburst assembly, large open and close speed of outburst ostium, complanation of inflation-style, dynamic development of recording process and high precision ,high reproducibility, are posses; and the conclusions that both quadratic curve expresses the relationship between moisture content and intensity of outburst, improved logarithmic relationship expresses the relationship between ground stress and intensity of outburst are obtained.更多还原