Lyu Jiabing, Tao Tiejun, Xie Caijin
School of Civil Engineering, Guizhou University, Guiyang, 550025, China.
School of Mining, Guizhou University, Guiyang, 550025, China.
Sci Rep. 2025 Apr 8;15(1):11968. doi: 10.1038/s41598-025-96636-w.
In the conventional radial uncoupled charge single free surface blasting, the bottom rock mass is difficult to be fully broken, which affects the blasting effect and restricts the tunneling efficiency. This difficulty adversely impacts the blasting outcome and limits the efficiency of excavation. To address this issue, this paper proposes a solution that involves modifying the charge structure to implement a variable diameter decoupled charge, and it analyzes the theoretical feasibility of this approach. The variably diameter decoupled charge and radial decoupled charge single-hole blasting model was established and compared using LS-DYNA. Furthermore, the effects of various parameters on the rock-breaking efficiency of variable diameter decoupled charges were analyzed. The results show that, in comparison to radially decoupled charges, variable diameter decoupled charges exhibit a greater explosive mass at their base. This enhancement leads to an increase in the effective stress on the surrounding rock, thereby effectively addressing the issue of inadequate fragmentation of the rock mass at the base of radially decoupled charges. Simultaneously, the directional effect of stress wave superposition and the balancing effect of the cavity on internal pressure contribute to an increase in the effective stress and reflected tensile stress of the overlying rock mass. This phenomenon ensures that effective fragmentation of the overlying rock mass can still be achieved, even with a relatively small amount of explosive charge. Under the condition of maintaining the same charge weight and borehole diameter, increasing the length and radius of the expanding section of the explosive significantly impacts rock fragmentation, whereas reducing the radius of the contracting section has a minimal effect. In engineering applications with a common borehole diameter of 4.2 cm, when the length of the expanding section of the explosive charge is half of the total charge length and the radius of the expanding section ranges from 1.65 cm to 1.70 cm, more effective rock fragmentation at the bottom can be achieved, resulting in an overall favorable fragmentation outcome.
在传统的径向不耦合装药单自由面爆破中，底部岩体难以充分破碎，这影响了爆破效果并制约了掘进效率。这一难题对爆破结果产生了不利影响，限制了开挖效率。为解决这一问题，本文提出了一种解决方案，即通过修改装药结构来实施变直径不耦合装药，并分析了该方法的理论可行性。利用LS-DYNA建立并比较了变直径不耦合装药与径向不耦合装药单孔爆破模型。此外，分析了各种参数对变直径不耦合装药破岩效率的影响。结果表明，与径向不耦合装药相比，变直径不耦合装药底部的炸药量更大。这种增加导致围岩有效应力增加，从而有效解决了径向不耦合装药底部岩体破碎不足的问题。同时，应力波叠加的定向效应和空腔对内压的平衡效应有助于增加上覆岩体的有效应力和反射拉应力。这一现象确保即使炸药量相对较少，也能实现上覆岩体的有效破碎。在保持装药重量和炮孔直径相同的条件下，增加炸药扩张段的长度和半径对岩石破碎有显著影响，而减小收缩段的半径影响最小。在炮孔直径为4.2厘米的工程应用中，当炸药扩张段的长度为总装药长度的一半且扩张段半径在1.65厘米至1.70厘米范围内时，底部可实现更有效的岩石破碎，从而获得总体良好的破碎效果。
