基于渗流-损伤耦合分析的煤层底板突水过程的数值模拟

Numerical simulation on water-inrush from the seam floor based on the coupled analysis of seepage and damage

根据杨村煤矿17煤的水文地质条件,应用岩石破裂过程渗流与损伤耦合作用分析系统(FRFPA2D),建立了薄煤层底板采动破坏的数值模型,模拟了采动条件下底板的破断失稳、裂隙扩展和突水过程,探讨了底板突水的机理,并对底板的易发生突水部位进行了预测。结果表明,当回采工作面推进到26.8m时,在隔水层的两个约束端产生拉剪破坏区。该破坏区和12灰贯通形成突水通道。突水后通道处的位移、流量都发生突变增加,并形成连锁反应,使12灰到13灰及其之间的隔水层依次发生破坏,最大破坏深度达13m,但未勾通和14灰、奥灰之间的水力联系,在底板没有断层的地段不会发生突水。两个工作面采前和采后压水试验结果表明,采动后底板破坏深度在9.96～12.35m,同数值模拟结果相吻合。

The present paper aims to introduce the authors＇ simulation of the instable failure process of seam floor above confined aquifer under mining. Our simulation was done numerically based on the thecry of the flow and damage coupling by using F-RFPA^2D（ Coupling System of Flow ＆ Solid in Rock Failure Process Analysis） . The paper also made a discussion with F-RFPA^2D the water outburst mechanism from the seam floor and predicted the position of the water outburst. In accordance with the geological conditions of Yangeun coalmine, a mechanical model for the mining process simulation of seam No. 17 with average height of 1.2 m was established. The simulation results show that, when the coal of 26.8 m long was mined, the failure zone caused by the shear and tension was developed due to the water retarding formation as well as other factors concerned in the nearby zones. Then the failure zone would gradually perforate into the underlying confined aquifer, which in turn may lead to the water outburst. In such a situation, the displacement and flow volume would increase suddenly after the water outburst. Statistically the vertical flow proved to be 650 m^3/（d· m） with the displacement being 700 ram. The maximum depth of the failure zone reached 13 m below the seam, And in turn the failure would also cause water-inrush from the karst aquifer No. 12 and No. 13 but might not be linked to karst aquifer No, 14 and Ordovician system. In such a case, the aquifer No. 14 and Ordoviclan system would usually turn to be the major threat to seam No. 17. As a matter of fact, the water-pressure test with Yangcun Coahnine before and after the coal excavation was designed with its two working faces, whose results indicate that the maximum fractured depth has reached 12.35 m under the seam floor. The given result is actually consistent with that of the numerical sinmlation. Therefore, F-RF- PA^213 can be used in predication of water-inrush in coahnining.