非稳态扩散双重附加效应下含瓦斯软硬煤共生体失稳致灾机制

In our country, coal and gas outburst disasters become more and more serious. The soft coal often exists in the area of coal and gas outbursts, and it can provide favorable conditions to coal and gas outbursts. However, the soft coal does not exist in isolation, and it is often combined with hard coal of normal structure in the same place. In this project, the soft coal and hard coal symbiont containing gas is regarded as the research object of this project, and the dual additional effects of mechanics and energy systems of symbiont induced by unsteady state diffusion will be concerned. The methods of laboratory experiment, theoretical analysis, numerical simulation and field verification will be used. Firstly, the equivalent structure characteristics of soft coal and hard coal will be obtained. The transition mechanism of gas unsteady state diffusion will be researched, and the gas unsteady state diffusion model will be established based on equivalent structure characteristics of coal. Then, the relationship of mechanical failure and damage evolution of symbiont containing gas will be analyzed, and the mechanism of crack initiation, expansion and penetration for symbiont containing gas will be stated. The mechanical failure behavior of symbiont containing gas will be obtained under the additional stress induced by the dual additional effects of unsteady state diffusion. Finally, the energy instability evolution model of soft coal and hard coal symbiont containing gas will be established, and the instability induced disaster mechanism of soft coal and hard coal symbiont containing gas will be revealed based on the unsteady state diffusion. This project is beneficial to the quantitative of outburst instability of soft coal and hard coal symbiont, and it can provide the theoretical basis for the gas outburst scientific prevention and control.

我国煤与瓦斯突出灾害形势严峻，在瓦斯突出发生的地点多发育着一定程度的构造软煤，软煤为突出灾害的发生提供了有利条件；煤层中软煤并非孤立存在的，多与原生结构硬煤呈组合共生的赋存形式。本项目以含瓦斯软硬煤共生体为研究对象，重点关注非稳态扩散对共生体力学和能量系统的双重附加效应，采用实验室实验、理论分析、数值模拟和现场验证相结合的方法，首先获得软煤与硬煤的等效结构特征，探讨煤中瓦斯扩散流态转换机制，建立基于等效结构特征的瓦斯非稳态扩散模型；然后分析含瓦斯软硬煤共生体力学破坏与损伤演化的关系，阐述含瓦斯共生体接触面的裂纹萌生、扩展与贯通机制，获得非稳态扩散附加应力下诱发含瓦斯共生体动态破坏特征；最后建立含瓦斯共生系统能量失稳演化模型，揭示非稳态扩散双重附加效应下含瓦斯共生系统失稳致灾机制。本项目成果将有助于提高含瓦斯软硬煤共生体突出失稳的定量化表征，为现场煤与瓦斯突出的科学防治提供理论基础。

煤矿资源的大量开采使得开采深度逐年增加，进而导致煤与瓦斯突出灾害日趋严重。煤矿现场赋存的构造煤为瓦斯突出提供了便利的条件，由于构造软煤多与原生结构的硬煤体共生赋存，使得软硬煤共生赋存条件下的瓦斯灾害的防治一直是研究难点。本项目针对这种煤层赋存特点与瓦斯灾害特征，以软硬煤共生体为研究对象，开展了煤的表面结构形态特征与内部孔隙结构特征实验，对软硬煤体孔裂隙表面形貌、内部结构和空间拓补特征进行了精细化的表征；获得了硬煤样、软煤样等效基质尺度和等效裂隙开度特征，建立了基于煤体等效结构特征的瓦斯非稳态扩散模型，获得了煤的非稳态扩散动力学特征。分析了煤粒尺度、应力路径和瓦斯状态等对共生体力学破坏的主控因素；构建了考虑解吸扩散的接触面附加应力计算模型，揭示含瓦斯软硬煤共生体接触面的裂纹扩展机制；探讨了开采过程解吸扩散附加应力诱发含瓦斯软硬煤共生体力学行为特征，结合数值模拟结果验证了相关理论。建立了应力-渗流-非稳态扩散多场控制模型和能量失稳判据，分析不同情境模式下巷道前方瓦斯压力、应力和塑性破坏的分布规律，获得了能量失稳前含瓦斯软硬煤共生体的初始损伤状态；定量分析共生煤体瓦斯突出能量的主控因素，揭示基于解吸扩散附加能量效应的共生煤体失稳致灾机制，最后提出了含瓦斯软硬煤共生体瓦斯突出的防治措施。项目研究成果有助于定量化表征软硬共生煤体的力学和能量失稳，完善了煤与瓦斯突出防治理论，为科学指导现场煤与瓦斯突出的防治工作提供理论基础。