【作者】 李坤；

【导师】 由长福；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2010， 博士

【摘要】 矿井灾害一直是我国开发煤炭资源所面临的严重难题。近些年来,继发性灾害发生频率增高,危害更严重,研究各种原发性灾害致继发性灾害发生规律对提出防治策略和指导人员逃生具有重要意义。本文开发了矿井动态通风网络分析系统及相关模型,并在其基础上研究了实际煤矿瓦斯异常涌出、瓦斯突出及火灾致继发性灾害发生规律,同时研究了掘进巷道火灾致瓦斯爆炸继发性灾害发生规律。建立了典型巷道、关键通风设施及典型井下原发性灾害的物理与数学模型,为整体通风网络分析系统建立奠定基础。采用集总参数和对流扩散方程建立典型巷道内气体输运模型,实现不同风流状态下气体输运模拟;建立了考虑挥发份燃烧的单-双膜固体燃烧单元模型,并基于离散化方法将其引入到类似皮带、电缆或木材等典型长条状物质的火灾蔓延过程模拟中,从而获得火灾释热量、烟气组分、火焰位置等的时间与空间动态演变过程,弥补了现有研究的不足;运用达西定律及气体动力学方程等描述瓦斯在“非破坏区”和“破坏区”流动特征,建立了适用于通风网络计算的煤与瓦斯突出模型;灾害情况下,风门可能被损坏或打开,通过分析风门或风窗开度与相对流通面积及通流能力的关系,建立了不同类型风门或风窗模型。结合流体网络分析方法与所开发模型,建立了可模拟井下通风状态、有害气体组分输运在典型灾害情况下随时间与空间变化过程的动态通风网络分析系统,并对其静态和动态计算准确性进行了实验验证。结果表明:所开发分析系统具有较高精度,与实验室实验结果相比,最大误差在5%左右。在此基础上,对实际煤矿继发性灾害发生规律进行了模拟研究。结果表明:工作面瓦斯异常涌出时,巷道内瓦斯最高浓度达到10%~15%时,危险浓度瓦斯存在时间最长;随着突出初始瓦斯压力提高,风流反向,与掘进巷道间接相连或距离较远区域诱发继发性灾害危险性最高。引入了含危险浓度瓦斯巷道平均体积,发现其与初始瓦斯压力呈良好二次函数关系;火灾下风流巷道易发生继发性灾害,与火灾同一巷道的区域,随着距火灾距离增加,诱发瓦斯爆炸或二次燃烧危险性及所持续时间增大。对火灾时期掘进巷道风流状态及瓦斯和温度分布规律进行了研究,获得了诱发瓦斯爆炸继发性灾害的影响规律。结果表明:火灾强度和位置并非诱发瓦斯爆炸关键因素;风筒断裂一定长度且巷道内存在危险浓度瓦斯时,低强度火灾诱发继发性灾害危险性较大。更多还原

【Abstract】 Mine disasters have always been a serious problem in China. Recently, the secondary catastrophes happened frequently and caused more serious consequences, but few studies have investigated it and there is still a big gap to totally understand the secondary catastrophes. It is quite important and meaningful to study on the characteristics so as to develop prevention strategies and save people. The dynamic analytical ventilation system and other relative models were firstly developed. Then, a real coal mine ventilation system was used to investigate the impact of sudden gas emission, coal and gas outburst and fires on the secondary catastrophes. Meantime, Simulations were established to investigate the influence of fires on the secondary catastrophe which is gas explosion in tunnels.Lumped-capacity method and convection-diffusion equation were used to establish the gas flow and diffusion model and the gas diffusion process under different conditions has been described. The single element combustion model simultaneously considering volatile and carbon reaction was developed. Based on the discrete method, the model was then used to develop a new fire model of long stick materials such as belt, wood and cable. The dynamic propogation of flame and all parameters including heat releasing rate and gas concentrations can be described. It provided a new way to study the fire phenomenon. Darcy Law and aerodynamics theory were used to describe the gas flow patterns in the“non-broken”region and“broken”region. The coal and gas outburst model was then established and good connections to ventilation network were achieved. When developing air door model of different kind, the relations between valve position and the relative flow area were analyzed and together with flow dynamics equations, they were used to determine the relations between air flow rate and valve position.The dynamic analytical platform was developed by using the model developed in this study and fluid network calculation method. A small scale experimental system was established to validate the platform. The comparison results show that platform has sufficient accuracy with the biggest error of 5% in both static and dynamic simulation. The platform was then used to investigate the influence of sudden gas emission, gas outburst and fire on secondary catastrophes in real coal mine. The results indicate that when sudden gas emission occurs, the secondary catastrophes can only happen in the tailgate and the duration time in which the secondary catastrophes may happen would be the longest when the highest gas concentration is between 10% and 15%. When gas outburst occurs, the air flows reversely in some tunnels. As the initial pressure increasing, the probability of secondary catastrophes is highest in the regions which are indirectly connected with the gas outburst tunnel. The average volume of tunnel with the gas concentration of 5%~16% was introduced, and it was found to be a quadratic function of the initial pressure. When fires occur, secondary combustion and gas explosion probably happen in the downward tunnel. As to the positions sharing the same tunnel with fires, the risk and duration time of secondary catastrophes increase as the distance from the fire increasing. Additionally, fire positions have direct influence on the distribution of tunnel regions with a high possibility of secondary catastrophes.The air flow patterns and gas and temperature distributions were finally simulated in the tunnel during the fire and the factors which may induce to secondary catastrophes were obtained. The results indicate that fire intensity and position have no significant influence on the gas and temperature distribution and are not the critical factors to secondary catastrophes. When ventilation tube destroyed and gas concentration between 5% and 16% appeared, fires of lower intensity had a higher possibility to induce to the secondary catastrophe as gas explosion.更多还原