爆破掘进动载作用下巷道顶板稳定机理研究

    Research on stability mechanism of roadway roof under dynamic loading induced by blasting excavation

    • 摘要: 针对爆破掘进过程中巷道直接顶因下沉与振动引发的顶板稳定性问题,以王坡煤业3203工作面高抽巷为工程背景,基于爆破动载衰减计算公式分析爆破动载作用下顶板受力特征及与爆破参数之间的相互关系,建立基于岩石抗拉强度的稳定判据,并量化爆破参数(装药长度、炮孔直径、炮孔长度)与顶板拉应力的关系,结合3203工作面高抽巷工程背景条件,提出了最优爆破参数组合。结果表明:爆破发生后作用在巷道顶板峰值压应力随炮孔长度和装药直径增大呈指数减小、随装药长度减小呈指数增大的规律,且与爆破参数均具有显著的敏感性;以抗拉强度为顶板稳定判据,得到了拉应力表达式,揭示了顶板在爆破动载作用下沿断面方向的拉应力与压应力相互转变现象,且最大拉应力分布在巷道直接顶中间位置,拉压拐点分布在直接顶靠近巷道两帮的位置;分析了顶板拉应力分布与爆破参数(炮孔长度、装药直径、装药长度)之间的量化关系,获得了保持3203工作面高抽巷直接顶稳定最优爆破参数为装药长度1.8 m、炮孔直径ϕ42 mm及炮孔长度2.4 m,结合具体工程实例得到了拉压拐点在0.6~0.8 m和2.6~2.8 m范围。工程实践验证了巷道直接顶在爆破掘进过程中没有发生拉破坏,成巷效果较好。

       

      Abstract: Addressing the stability issues of the immediate roof in roadways caused by subsidence and vibration during blasting excavation, this study takes the high-level drainage roadway of Panel 3203 in Wangpo Coal Mine as the engineering background. Based on the calculation formula for blasting dynamic load attenuation, the stress characteristics of the roof under blasting loads and their interrelationship with blasting parameters were analyzed. A stability criterion based on the tensile strength of the rock was established, and the quantitative relationship between blasting parameters (charge length, borehole diameter, borehole length) and roof tensile stress was determined. Combining this with the specific engineering conditions of the 3203 high-level drainage roadway, an optimal combination of blasting parameters was proposed. The research results indicate that after blasting, the peak compressive stress acting on the roadway roof exhibits an exponential decrease with increasing borehole length and charge diameter, and an exponential increase with decreasing charge length. Furthermore, it shows significant sensitivity to all these blasting parameters; using tensile strength as the stability criterion for the roof, a tensile stress expression was derived. This expression reveals the phenomenon of transition between tensile stress and compressive stress along the cross-section of the roof under blasting dynamic loads. The maximum tensile stress is distributed in the middle of the roadway immediate roof, while the tensile-compressive transition points (inflection points) are located near the ribs (sidewalls) of the roadway; the quantitative relationship between the distribution of roof tensile stress and blasting parameters (borehole length, charge diameter, charge length) was analyzed. The optimal blasting parameters for maintaining the stability of the immediate roof in the 3203 high-level drainage roadway were determined as: charge length of 1.8 m, borehole diameter of ϕ42 mm, and borehole length of 2.4 m. Combined with a specific engineering case, the tensile-compressive transition points were found within the ranges of 0.6-0.8 m and 2.6-2.8 m from the centerline. Engineering practive verification confirmed that the immediate roof did not experience tensile failure during the blasting excavation process, resulting in effective roadway formation.

       

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