采动煤岩体弹脆塑性损伤本构模型及应用

CONSTITUTIVE MODEL FOR ELASTO-BRITTLE-PLASTIC DAMAGE OF COAL ROCK MASS DUE TO MINING AND ITS APPLICATION

为提高保护层开采的有效性、安全性和经济性,通过引入理想弹脆塑性模型和内切圆准则,采用FLAC3D技术,在德鲁克–普拉格塑性流动格式基础上建立采动煤岩体弹脆塑性损伤本构模型的数值格式。利用VC++2005开发环境将本构模型编写成可供FLAC3D软件调用的自定义模型,并通过试件单轴和三轴压缩数值试验的对比,验证模型用于研究采动煤岩体脆性应变软化特征的正确性和合理性。将所建立模型用于阳泉新景矿超远距离保护层开采的数值模拟得出:位于保护层上部125m的超远距离被保护煤层处于裂隙带上边缘,被保护层卸压瓦斯取得良好效果,能利用保护层开采及被保护层卸压瓦斯抽采消除被保护层的突出危险。计算结果与物理相似模拟结果基本吻合,表明所建立的采动煤岩体弹脆塑性损伤本构模型可用于保护层开采及被保护层卸压瓦斯抽采效果的预评价。模拟结果可为保护层开采及被保护层卸压瓦斯抽采设计提供合理建议。

The exploitation of the protective layer and pressure-relief gas drainage is an effective primary method to eliminate coal and gas outburst and it is widely used in many mineral fields. In order to improve the effectiveness, safety and economy of the protective layer mining, a set of numerical equations of elasto-brittle-plastic constitutive model of coal rock mass damage due to mining are set up based on the plastic flow format of Drucker-Prager constitutive model in fast Lagrangian analysis of Continua in 3-dimension continua（FLAC^3D）. And the model is modified by using the inscribed circle criterion and the ideal brittle-plastic model. The model is developed into DLL file in VC＋＋2005 programming environment for FLAC^3D; and the correctness and rationality of this model used to study the brittle strain-softening characteristics of coal rock mass due to mining are validated by comparing with uniaxial and triaxial compression numerical tests. This model is used to simulate the super-remote protected seams exploitation of Xinjing coal mine in Yangquan coal field. The results show that the protected layer lies in the top edge of fractured zone 125 m away from the protected layer; and the relieved gas in the super-remote protected layers could be better drained utilizing the mining influence of the protective layer. And the conclusions agree with that of the similar experiment, which indicates that the elasto-brittle-plastie constitutive model of coal rock mass damage due to mining could be used to preliminary evaluation of protective layer mining and relief-pressure gas drainage. Simulation results may protective layer mining and relief-pressure gas drainage.