大直径瓦斯抽采钻孔穿越保护煤柱围岩变形损伤规律

Deformation and Damage Law of Surrounding Rock of Large DiameterGas Extraction Drilling Through Protected Coal Pillar

为探究大直径钻孔穿越保护煤柱的钻孔围岩破坏规律,采用ABAQUS进行数值模拟分析,在软件中嵌入Concrete damage model屈服准则,并分析了塑性准则下的煤体、泥岩的抗压强度、抗拉强度与损伤因子演化规律。以平舒煤矿81117工作面为例建立数值模型,探究了钻孔开挖以及工作面采动条件下的煤柱围岩应力、位移、损伤特征。结果表明:煤体与泥岩的抗压、抗拉强度与损伤因子具有相同规律的演化形式,但泥岩具有更高的强度特性。钻孔开挖对保护煤柱的损伤影响较小,而工作面的采动作用将会导致围岩出现明显的变形损伤,回采300 m时,钻孔的位移量约为-0.08 m,回采600 m时,钻孔的位移量达到0.32 m,巷道顶底板与煤柱塑性区存在贯通破坏风险。

In order to explore the damage law of the surrounding rock of large-diameter boreholes through the protected coal pillar,the numerical model was established by ABAQUS in the 81117 working face of Pingshu Coal Mine.The Concrete damage model yield criterion was embedded in the software,and the strength and damage factor evolution law of coal and mudstone under plastic criterion were analyzed.The results showed that the strength and damage factor of coal and mudstone have the same regular evolution form,but mudstone has higher strength characteristics.The impact of drilling and excavation on the damage of protecting coal pillar is relatively small,while the mining action of the working face will lead to obvious deformation and damage of the surrounding rock.The displacement of the drilling hole is about-0.08 m in 300 m of mining,and the displacement of the drilling hole reaches 0.32 m in 600 m of mining.There is the risk of penetrating and damaging the plastic zone between the top and bottom of the tunnel and the coal pillar.