基于双孔结构等效特征的卸荷煤体损伤-渗流协同响应机制

Pressure relief and permeability enhancement is an important technology to eliminate the coal and gas outburst danger in coal seams with high gas content and low permeability. During the measures of pressure relief and permeability enhancement in coal seams were carried out, the coal structure was damaged due to the unloading. It has become the key factors affecting the implementation of pressure relief and permeability enhancement technology that how to characterize accurately the structural characteristics of unloading coal and its permeability evolution law. Based on this, the complex coal structure will be simplified in an equivalent way and the scale effect and equivalent characteristics of the dual-porosity structure of unloading coal will be studied deeply, and then the structural changes of different coal bodies will be further reflected. The synchronous stress-acoustic emission-permeability experiments will be carried out to reveal the cooperative evolution law of the unloading gassy coal damage and gas flow based on the equivalent characteristics of dual-porosity structure. The volume response characteristics of unloading gassy coal will be analyzed and the mechanical constitutive equation is going to be built. The gas-solid coupling model for unloading coal containing gas will be established based on the equivalent characteristics of dual-porosity structure for analyzing the relationship between the coal seam permeability and the equivalent characteristics of dual-porosity structure of unloading coal. The effect of the equivalent characteristics of dual-porosity structure on the permeability of coal seams will be studied by the numerical simulation. Then, the above research results will be verified and evaluated by combining the field data. The research results can be used to predict the regional distribution characteristics of permeability in coal seams with pressure released and guide the engineering design of the gas extraction.

卸压增透是消除高瓦斯低透气性煤层突出危险性的重要技术手段。在卸压增透过程中，煤体结构发生卸荷损伤破坏，如何准确描述卸荷煤体复杂结构及渗透率演化特征成为卸压增透技术实施时面临的关键问题。基于此，本项目将煤体结构通过等效的方式进行简化，深入研究卸荷煤体双孔结构尺度效应及其等效特征，并进一步反映不同煤体的结构变化；开展卸荷煤体应力-声发射-渗流同步试验，获得基于双孔结构等效特征的含瓦斯卸荷煤体损伤-渗流协同演化特性；分析卸荷损伤过程中含瓦斯煤的体积响应特征并建立其力学本构方程，研究含瓦斯卸荷煤体应力场、变形场、渗流场等多场耦合机制及其与煤体双孔结构等效特征的关系，构建基于双孔结构等效特征的含瓦斯卸荷煤体气固耦合模型；结合数值分析手段，研究卸荷煤体双孔结构等效特征对煤层渗透性的影响，并通过现场实测渗透率数据进行对比验证。上述研究成果可用于预测卸压增透煤层渗透性区域分布特征，指导瓦斯抽采工程设计。

卸压增透是消除高瓦斯低透气性煤层突出危险性的重要技术手段。在卸压增透过程中，煤体结构发生卸荷损伤破坏，如何准确描述煤体复杂结构及渗透率演化特征成为卸压增透技术实施时面临的关键问题。基于此，本项目将煤体结构通过等效的方式进行简化，深入研究煤体双孔结构尺度效应及其等效特征，并进一步反映不同煤体的结构变化；开展煤体应力-损伤-渗流同步试验，获得基于双孔结构等效特征的含瓦斯煤体损伤-渗流协同演化特性；分析损伤过程中含瓦斯煤的体积响应特征并建立其力学本构方程，研究含瓦斯煤体应力场、变形场、渗流场等多场耦合机制及其与煤体双孔结构等效特征的关系，构建基于双孔结构等效特征的含瓦斯煤体气固耦合模型；结合数值分析手段，研究煤体双孔结构等效特征对煤层渗透性的影响，并通过现场实测渗透率数据进行对比验证。上述研究成果可用于预测卸压增透煤层渗透性区域分布特征，指导瓦斯抽采工程设计。