岩溶陷落柱围岩支承压力-渗流演化特征数值模拟

Numerical simulation of abutment pressure-seepage evolution characteristics of surrounding rock of karst collapse column

为保证含陷落柱复杂煤层的安全开采,合理确定煤柱尺寸对于此类煤层水害防治至关重要。采用理论分析与数值模拟建立固-液耦合模型计算手段,计算了孔隙水压力与安全煤柱尺寸之间关系,分析了开采过程中围岩支承压力演化过程、围岩变形破坏规律、渗流演化特征等。结果表明:随着陷落柱内部孔隙水压力的不断增加,满足安全需求的煤柱尺寸增加;围岩应力分布特征呈“拱壳”型,拱顶在工作面倾斜上部区域;开采引起的围岩支承压力与陷落柱体侧支承压力存在“增强-降低-再增强”演化过程;支承压力叠加导致工作面围岩产生大量裂隙是陷落柱导水通道产生的主要原因;工作面围岩塑性区分布呈“马鞍形”;随着工作面不断推进,渗流影响范围不断增大,渗流轮廓呈梯度型分布,煤柱处孔隙水压力不断升高;综合确定了合理煤柱尺寸。研究结果为现场实际生产提供参考依据。

In order to ensure the safe mining of coal seams with karst collapse column,reasonable determination of coal pillar dimensions is essential for the prevention of water damage in such coal seams.This paper used the combination of theoretical calculation and numerical simulation to establish a solid-liquid coupling model with the relationship between pore pressure and safe coal pillar size analyzed;the evolution process of abutment pressure under the coupling field during mining was explored as well as the deformation and failure law of surrounding rock,the evolution characteristics of seepage flow,etc.Research indicates:With the continuous increase of the pore pressure inside the collapse column,the size of the coal pillars meeting the safety requirements increased approximately positively.During the process of propulsion,the evolutionary process of“coupling enhancement-coupling reduction-coupling re-enhancement”exists in the surrounding rock abutment pressure caused by mining and the lateral abutment pressure of the collapsed column.The superimposed of abutment pressure is the main cause of the water channel of the collapse column.The plastic zone of the surrounding rock is“saddle shape”.As the working face continues to advance,the range of seepage fields is increasing,and the pore pressure at the coal pillar rising.At last,this paper also determined the reasonable coal pillar size.The research results provide a reference for actual production on site.