动静载作用下含瓦斯煤动力响应特征及突出机制研究

The mining and excavation working faces of underground coal mine are normally in a combined condition with both dynamic and static loads. The dynamic disturbance is the direct reason inducing coal and gas outburst, because it could cause coal and rock damaged and unstable. Very few experimental and theoretical studies have been conducted to understand the influence of dynamic and static loads on the dynamical response of gas-bearing coal. Based on self-designed ‘coal-gas coupling test apparatus’ and using helium and methane as experimental gases, this project aims at investigating the influences of quasi-static load and combined dynamic and static load on the gas pressure in pores and the characteristics of dynamical response and coal damage. The interaction effect among unstable adsorption-desorption, fracture development and coal damage under different loads will be studied. The mathematical model of the relationship between stress and pore press will be established. The characteristics of pore pressure change and damage of methane-bearing coal under dynamic and static loads is expected to be revealed. Based on the theoretical and experimental results and building the engineering structure of coal and gas outburst, numerical simulation, physical simulation and gas outburst accident analysis will be comprehensively used to understand the energy and incident development rules of gas outburst in underground condition. The expected results may provide theoretical foundations for the monitoring, alarming and prevention of coal and gas outburst.

煤矿井下采掘工作面附近煤岩体处于典型的动静载叠加作用环境中，动力扰动促使煤岩破坏失稳是诱发煤与瓦斯突出灾害的直接原因，而以往关于动静载组合作用下含瓦斯煤动力响应特征的实验和理论研究较少。本项目拟利用自行设计改进的“气固耦合实验系统”，采用甲烷和氦气为实验气体，分别考察准静载、动静组合加载作用下含瓦斯煤孔隙压力动态响应规律和损伤破坏特征；研究不同载荷作用下含瓦斯煤非稳态吸附解吸与孔隙压力动态变化、裂隙扩张及损伤破坏的互馈作用效应，建立含瓦斯煤应力-孔压耦合作用数力学模型和动态本构方程，揭示动静载作用下含瓦斯煤的孔隙压力动态响应与损伤破坏耦合作用机理；基于上述实验和理论分析结果，通过构建煤与瓦斯突出工程结构模型，结合数值模拟、物理实验和突出事故案例分析等方法，探索煤矿井下动静载叠加作用环境下含瓦斯煤体失稳过程的能量演化规律和突出灾变机制。预期研究成果可为突出监测预警和防控提供一定的理论基础。

煤矿井下采掘工作面附近煤岩体处于典型的动静载叠加作用环境中，动力扰动促使煤岩破坏失稳是诱发煤与瓦斯突出灾害的直接原因，而以往关于动静载组合作用下含瓦斯煤动力响应特征的实验和理论研究较少。.本项目发展了准静态及动静组合加载作用下含瓦斯煤体孔隙压力响应规律和损伤破坏特性的测定装置和实验方法，通过开展不同加载速率条件下含瓦斯煤损伤破坏和孔隙压力响应实验，发现了加载过程中孔隙气体压力会先经历一个上升阶段达到峰值压力点；得出了不同加载速率条件下含瓦斯煤体损伤破坏特征、裂隙扩展和孔隙压力动态变化规律，并掌握了影响孔隙压力响应的主要控制因素；推导和建立了含瓦斯煤基质孔裂隙率演化模型和渗透率方程、瓦斯运移控制方程，并基于新型统计损伤变量定义了考虑应变率影响的损伤模型，构建了含瓦斯煤多场耦合控制方程组；借助COMSOL Multiphysics软件模拟分析了含瓦斯煤受载损伤破坏和孔隙压力响应规律，进一步研究了动静载作用下煤体损伤过程中孔隙瓦斯压力和裂隙瓦斯压力的响应规律；揭示了动静载荷作用条件下煤体孔裂隙瓦斯压力变化与损伤破坏的互馈作用机制，明确认识到在采掘扰动或动载荷作用下，采掘工作面前方瓦斯压力会出现局部增高的现象；通过开展物理模拟试验，验证并完善了煤与瓦斯突出关键结构体致灾机理，掌握了煤矿井下动静载叠加作用环境下含瓦斯煤体突出灾变机制；提出了煤与瓦斯突出危险层次化精准辨识的技术思路。.本项目研究成果加深了对煤与瓦斯突出发生机理的认识，为突出灾害科学防治提供了新的理论支撑，为煤与瓦斯突出预测和预警工作指明了方向。