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Fine controlled blasting of subsurface excavation for subway stations in soft–hard mixed-medium rock mass
Tunnelling and Underground Space Technology ( IF 6.7 ) Pub Date : 2025-01-20 , DOI: 10.1016/j.tust.2025.106407
Wanzhi Zhang, Jie Mei, Keguo Sun, Bangshu Xu

Drilling and blasting excavation methods along with primary arch-cover primary supports are frequently employed in the construction of urban subway stations. However, traditional blasting methods fail to control tunnel face flatness, overbreak, and underbreak in soft–hard mixed-medium rock mass owing to symmetric and invariable blasting parameters. The Shishan Road Station of Qingdao Metro Line 6 is located in a soft–hard mixed-medium rock mass. Traditional blasting excavation methods result in considerable over-excavation of the soft rock on the one side, forming a concave inside, and minor over- and under-excavation of the hard rock on the opposite side, forming a convex outside. Herein, numerical models were developed to analyze the rock damage caused by contour blasting in soft–hard mixed-medium rock mass. Different perimeter hole spacings, burden thicknesses, and charge weights were investigated to identify the optimal parameters. Based on these models, this study proposes an asymmetric blasthole pattern and charge parameters, such as a smaller spacing and charge weight on the soft rock side and deeper hole lengths on the hard rock side. In addition, higher delay times were suggested to control the blasting vibration. Field tests showed that the optimized blasting scheme effectively controlled the flatness, overbreak, and underbreak. The utilization rate of blast holes increased by 5%, the average overbreak area decreased by 57.3%, and underbreak did not occur. The blasting energy of a single initiation and the proportion of low-frequency energy decreased significantly, resulting in better control of rock damage caused by blasting vibrations.

中文翻译:


在软-硬-混合-介质岩体中对地铁站的地下开挖进行精细控制爆破



钻孔和爆破开挖方法以及初级拱形覆盖初级支护经常用于城市地铁站的建设。然而,由于爆破参数对称且不变,传统的爆破方法无法控制软硬混合介质岩体中的隧道掌面平整度、超挖和欠挖。青岛地铁 6 号线狮山路站位于软硬混合介质岩体中。传统的爆破开挖方法导致一侧软岩出现相当大的超挖,内部形成凹陷,而另一侧的硬岩则出现轻微的过挖和欠挖,形成外凸。在此,开发了数值模型来分析等高爆破在软-硬混合-中等岩体中造成的岩石损伤。研究了不同的周长孔间距、负载厚度和装药重量,以确定最佳参数。基于这些模型,本研究提出了一种不对称的爆破孔模式和装药参数,例如软岩侧的间距和装药重量较小,而硬岩侧的孔长较深。此外,建议更高的延迟时间来控制爆破振动。现场试验表明,优化后的爆破方案有效控制了平整度、超挖和欠挖。爆破孔利用率提高了 5%,平均超挖面积减少了 57.3%,未发生欠挖。单次起爆的爆破能量和低频能量的比例显著降低,从而更好地控制了爆破振动引起的岩石损伤。
更新日期:2025-01-20
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