复杂环境下齐次定向爆破拆除四座烟囱的实践

Practice on Demolition of Four Chimneys by Homogeneous Directional Blasting in Complex Environment

为成功爆破拆除复杂环境下位于同一厂区的两座砖烟囱和两座钢筋混凝土烟囱,通过分析周边环境条件以及烟囱结构特点,确定“单切口,定向倒塌”的总体爆破方案对四座烟囱进行齐次拆除。根据工程经验确定烟囱切口底边位置为标高+0.5 m处,切口角度为215°,切口高度、切口长度以及相关爆破参数通过理论公式计算得到具体数值,切口形式采用类梯形切口,起爆网路采用精准度更高的数码电子雷管起爆系统以顺发齐爆的方式进行起爆。考虑四座烟囱不同的结构组成分别制定对应的预处理方案,并通过对烟囱的倒塌可靠性、爆破振动、倒塌振动进行安全校核以及对爆后飞溅碎片和爆破飞石的有效控制,从而确保四座烟囱按设计方向倒塌,防止对周围保护目标造成危害。通过使用有限元软件LS-DYNA对四座烟囱的倒塌过程进行模拟,结果表明模拟倒塌过程与实际过程几乎一致,倒塌完成时间均在14 s左右,并且通过分析顶部节点的位移与速度规律可以判断烟囱倒塌效果充分,达到预期目标,进一步表明了数值模拟对工程实践的指导意义,可为类似工程提供参考。

In order to successfully demolish two brick chimneys and two reinforced concrete chimneys located in the same plant area where is a complex environment by blasting.The overall blasting scheme of“single cut,directional collapse”is determined to demolish the four chimneys at one time,by analyzing the surrounding environmental conditions and the structural characteristics.According to the engineering experience,it is determined that the bottom edge of the chimney cut is at the elevation of+0.5 m,the cut angle is 215°,the cut height,cut length and relevant blasting parameters are calculated by theoretical formula.The cut form is trapezoid like,and the initiation network uses the digital electronic detonator initiation system with higher accuracy to initiate in the way of parallel firing.Considering the different structural composition of the four chimneys,corresponding pretreatment schemes are formulated respectively.Through the safety check of the collapse reliability,blasting vibration and collapse vibration of the chimneys and the effective control of the flying debris and flying stones after blasting,the four chimneys collapse in the design direction and prevent harm to the surrounding protection targets.By using the finite element software LS-DYNA to simulate the collapse process of four chimneys,the results show that the simulated collapse process is almost the same as the actual process,and the collapse completion time is around 14 s.Moreover,by analyzing the displacement and velocity law of the top node,it can be judged that the chimney collapse effect is sufficient and the expected goal is achieved,which further shows a guiding significance of the numerical simulation for engineering practice and can provide reference for similar projects.