煤炭地下气化(UCG)是一种将煤炭资源低碳化利用的技术，在中国的低碳经济下具有很好的前景。然而，全球煤炭地下气化经历几十年的现场试验，目前仍有许多待解决的问题。在煤炭地下气化过程中，气化区域随着煤层中裂纹和裂隙的扩展不断扩大，若不能有效监测和控制气化区域，将会引起煤层顶板岩层过度破坏，从而导致气体泄漏、地表沉陷和水污染等问题。为此，提出了以声发射活动参数及变化规律为基础评价气化过程中煤体的破裂及演化活动。利用板状和柱状煤样进行了一系列热履历试验，采用声发射(AE)监测和X射线扫描技术监测煤样加热前后的内部结构变化，研究温度、层理面与加热面方向对煤样破裂和裂隙扩展的影响。结果表明在对煤样表面加热的过程中，煤样表面及内部会产生许多裂纹和裂隙，并释放大量声发射信号;煤样的加热温度变化越快，声发射活性越高，产生的微裂纹越多;煤样内部产生微裂纹的方向与煤层理面趋向于平行。介绍了一种基于声发射活动参量的地下气化破裂区标定模型试验。分别测定了气化过程中的温度分布、声发射活动、气化煤气成分和气化煤量等。揭示了气化条件下煤体内部裂隙产生演化与声发射的内在联系，证明了声发射监测技术能够达到对气化过程中煤岩体破裂及演化区域进行预测及评价的目的。

Underground coal gasification (UCG) is a kind of low-carbon utilization technology of coal resources,which has a good prospect in China’s low-carbon economy.However,the global underground coal gasification has experienced several decades of field tests,and there are still many problems to be solved.In the underground coal gasification process,the gasification zone growth with crack extension inside the coal seam.It will lead to excessive destruction of coal seam roof strata,resulting in gas leakage,surface subsidence,water pollution and other problems,if the gasification zone cannot be effectively monitored and controlled.To this end,it is proposed to evaluate the rupture and evolution of coal during gasification based on acoustic emission parameters and variation laws.The effects of temperature,the direction of the stratified plane,and the inherent microcracks on the coal fracture and crack extension were investigated by some heating experiments with plate-shaped and cylindrical coal specimens.To monitor the failure process and to measure the microcrack distribution inside the coal specimen before and after heating,the acoustic emission (AE)analysis and the X-ray CT were applied.The results show that in the process of heating the surface of the coal sample,many cracks and fissures will be produced on the surface and inside of the coal sample,and a large number of acoustic emission signals will be released.The faster the heating temperature changes,the higher the acoustic emission activity,the more microcracks are produced,and the direction of microcracks in the coal sample tends to be parallel to the coal seam surface.A laboratory-scale UCG model experiment was conducted with set design and operating parameters.The temperature profiles,AE activities,product gas components as well as the gasifier weight loss were measured successively during gasification.It reveals the intrinsic relationship between the evolution of internal fissures and acoustic emission,and it proves that the acoustic emission monitoring technology can predict and evaluate the fracture and evolution area of coal and rock mass in the gasification process.

1 煤样加热试验

   1.1 实验仪器及步骤

   1.2 板状和圆柱状煤样热履历试验

2 UCG 模型实验

   2.1 实验设计

   2.2 结果与讨论

3 结论