构造应力场煤巷掘进冲击地压能量分区演化机制

Mechanism of energy partition evolution of excavation roadway rockburst in coal seam under tectonic stress field

在新建深部矿井,原岩应力区煤巷掘进冲击地压问题日益突出,且现场破坏具有区间性和方位性特征,为揭示这一机制,针对深部构造应力场条件下的煤层掘巷,基于数值模拟和理论分析研究,建立不同掘进速度下围岩弹性能空间分区演化模型,划定能量非稳态释放边界,分析其分布形态与能量特征,结论与现场实际破坏情况较为吻合。研究结果表明:依据弹性能所处状态及变化特征的不同,构造应力场煤巷掘进围岩在空间上可划分为6类区间,顶底板内同时分布能量积聚区和释放区,而巷帮仅存在能量释放区,这与最大主应力的做功特征密切相关。掘进速度增大时,围岩弹性能释放区的走向范围将同时向两端扩展,非稳态释能边界沿走向不断拉长,具有冲击风险的范围不断扩大。构造应力场中,巷帮潜在冲击启动区位于工作面附近,其冲击发生必要条件包括高原岩应力和快速掘进。巷帮和工作面潜在冲击启动区均位于围岩浅部。由于滞后区顶底板能量非稳态释放前积聚水平更高,加上顶板和帮部支护作用,导致底板滞后区冲击破坏强度要大于工作面附近顶底板和巷帮冲击破坏强度。研究结论与构造应力场现实冲击案例较为吻合,对构造应力场煤巷掘进冲击地压监测预警及解危方法的研究具有参考意义。

In the newly built deep mine,the rockburst in in-situ stress area gradually increases,and the site damage has regional and directional characteristics.In order to reveal this mechanism,a spatial partition evolution model of excavation roadway surrounding rock under different heading speeds based on the numerical simulation under the condition of deep tectonic stress field is established.The distribution boundary of energy unsteady release boundary is defined.Its distribution pattern and energy characteristics is analyzed.The conclusion is consistent with the situation on site.The results show that the surrounding rock of excavation roadway can be divided into six types of space according to the elasticity of the state and the characteristics of change.The energy accumulation area and the release area are both distributed in the roof and floor,but there is energy release area only in the roadway wall.When the heading speed increases,the direction of the elastic energy release area of the surrounding rock will expand to both ends at the same time,and the unsteady release boundary will be elongated along the way,and the range of rockburst risk will be expanded.In the tectonic stress field,the potential rockburst zone of the roadway is near the heading face,and the necessary conditions for its rockburst include the high in-situ stress and the rapid excavation.The potential burst start-up of roadway wall and face are located in shallow rock.The energy accumulation level of the roof and floor far away from the face is higher,and the roof and wall have bolt support,which lead to the rockburst damage strength of roof and floor far away from the face is greater than that close to the face.The conclusion is of significance for the study of the early warning and the method of detecting rockburst in the tectonic stress field.