Research on mechanical response of artificial dam under gas explosion in roadway
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摘要: 当矿井发生瓦斯爆炸时,爆炸冲击波会破坏储水坝体,导致采空区储水大量涌出,甚至造成瓦斯与水耦合灾害,因此,人工坝体在极端条件下的稳定性对矿井安全具有重要意义。针对当前对井下人工坝体随瓦斯爆炸冲击波传播的力学响应特性研究较少的问题,利用LS−DYNA软件模拟了巷道内瓦斯爆炸对人工坝体力学性能的影响,研究了迎爆侧、黄土夹层及背爆侧受力状态、形变和应力特征,分析了巷道内瓦斯爆炸冲击波作用下人工坝体的动力响应过程。人工坝体表面载荷分布分析结果表明:当巷道内部发生爆炸时,人工坝体迎爆面的爆炸荷载为不均匀分布,同时在井下各结构相交区域,反射超压因反射冲击波的汇聚和叠加作用而产生明显的增强效应;随着爆炸能量的快速释放,迎爆面中心测点的冲量加载时程曲线表现为三阶段变化特征,当瓦斯体积为200 m3时,在起爆500 ms内,迎爆面中心测点的最大冲量可以达到0.04 MPa·s。人工坝体表面形变和应力分析结果表明:在0~500 ms内,迎爆面中部始终处于受压状态,中心节点的最大横向位移为0.319 mm,由于掏槽的作用,人工坝体四周受拉应力,在此处出现了最大拉应力及剪切应力;黄土夹层动力响应依次为“受压−压实−塑变−传压”,在该过程中黄土起到缓冲作用,最大位移为0.067 5 mm;背爆侧墙体由于受到黄土夹层的挤压而发生力学响应,但应力都较小,外侧墙体基本处于安全状态。Abstract: When a gas explosion occurs in a mine, the explosion shock wave can damage the water storage dam, leading to a large amount of water gushing out of the goaf, and even causing gas water coupling disasters. Therefore, the stability of artificial dams under extreme conditions is of great significance for mine safety. Currently, there's a lack of research on the mechanical response features of underground artificial dams propagating with gas explosion shock waves. In order to solve the above problems, the LS-DYNA software is used to simulate the impact of gas explosion in roadways on the mechanical properties of artificial dams. The stress state, deformation, and stress features of the explosion facing side, loess interlayer, and explosion backing side are studied. The dynamic response process of artificial dams under the action of gas explosion shock waves in roadways is analyzed. The analysis results of the load distribution on the surface of the artificial dam indicate that when an explosion occurs inside the roadway, the explosion load on the explosion facing surface of the artificial dam is unevenly distributed. At the same time, in the intersection area of various underground structures, the reflected overpressure has a significant strengthening effect due to the convergence and superposition of reflected shock waves. With the rapid release of explosive energy, the impulse loading time history curve of the central measuring point on the explosion facing surface exhibits a three-stage change feature. When the gas volume is 200 m3, the maximum impulse of the central measuring point on the explosion facing surface can reach 0.04 MPa·s within 500 ms of explosion. The results of deformation and stress analysis on the surface of the artificial dam indicate that within 0-500 ms, the central part of the explosion facing surface is always under compressive stress. The maximum lateral displacement of the central node is 0.319 mm. Due to the effect of cutting, the artificial dam is subjected to tensile stress around it, where the maximum tensile and shear stresses occur. The dynamic response of the loess interlayer is in the order of "compression - compaction - plastic deformation - pressure transfer", during which the loess plays a buffering role, with a maximum displacement of 0.067 5 mm. The wall of the explosion backing side undergoes mechanical response due to the compression of the loess interlayer. But the stress is relatively small, and the outer wall is basically in a safe state.
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表 1 混合气体材料及状态方程参数
Table 1. Parameters of mixed gas material and its state equation
甲烷体积分数/% 密度/(kg·m−3) 爆速/(m·s−1) 爆热/(MJ·kg−1) E/(MJ·m−3) V C0—C3 C4,C5 C6 9.5 1.234 1 855 2.762 3.4 1 0 0.274 0 表 2 空气材料及状态方程参数
Table 2. Parameters of air material and its state equation
材料 密度/(kg·m−3) C0 C1—C3 C4 C5 C6 E/(MJ·m−3) V 空气 1.29 −1×105 0 0.4 0.4 0 0.25 1 表 3 黄土及围岩材料参数
Table 3. Parameters of loess and rock layer materials
材料 密度/(kg·m−3) 泊松比 弹性模量/Pa 黄土 1 810 0.45 2.40×107 围岩 2 600 0.19 2.07×1010 -
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