摘要
为了模拟裂隙和非均质煤岩损伤劣化对煤层瓦斯抽放过程的影响,将煤岩视作拟连续介质和裂隙组成的双重介质.拟连续介质(煤岩)视作弹性损伤材料,煤岩的弹性模量、强度的非均匀性用Weibull分布模拟,裂隙利用薄层Desai单元模拟.基于弹性损伤理论考虑煤岩应力状态及损伤与透气系数的耦合,建立了煤岩瓦斯渗流-应力耦合模型,并在数值计算程序Coupling Analysis中开发了相应的计算模块.利用建立的模型模拟了某瓦斯抽放试井瓦斯抽放,结果表明在瓦斯抽放过程中,有效应力变化诱发部分煤岩单元发生损伤,损伤区透气系数最大增加了约2.7倍,受围压影响,非损伤区的透气系数减小,减小的最大幅度达到95%.研究表明,建立的模型能较好地模拟煤岩应力和损伤及煤岩力学参数的非均匀性对透气系数的影响,从而为瓦斯抽放过程模拟提供了一种有效方法.
To simulate effects of fractures and heterogeneous coal＇ damage on gas drainage,coal is viewed as double media composed of continuous and fractured media.The heterogeniety of Young＇s modulus and strength of continuous coal is simulated with Weilbull distribution,and the crack（fractured media） is simulated with Desai thin element.Based on elastic damage theory of coal,coupling of stress and damage with permeability for coal is taken into account,and the seepage-stress coupling mathematical model is presented.Numerical code is developed in Coupling Analysis.Gas drainage progress for a gas well is also simulated with the model.The result shows that the change in effective stress induces the damage of some elements during gas drainage.In damage area,the maximum of gas permeability coefficient increases by 2.7 times.Due to confining pressure,the maximum of gas permeability coefficient in elastic area decreases by 95%.Results also show that the model can simulate the effect of stress,damage and heterogeneity of coal on gas permeability coefficient,and an effective method is povided to simulate gas drainage.
出处
《采矿与安全工程学报》
EI
北大核心
2009年第4期481-485,共5页
Journal of Mining & Safety Engineering
基金
国家自然科学基金重点项目(50434020)
