复杂环境下含人字形内衬的180 m烟囱爆破拆除

Blasting Demolition of 180 m Chimney with Herringbone Lining in Complex Environment

针对武汉钢铁厂二烧180 m钢筋混凝土烟囱具有内含人字墙、大体积内衬及临近煤气管道的爆破拆除难题,采用ANSYS/LS-DYNA有限元软件论证了“开凿超大拱形导向窗,提高爆破切口”优化方案的可行性。计算结果表明:爆破切口产生后,内衬的垮塌堆积速度明显大于爆破切口的闭合速度。采用一般定向倾倒方案时,烟囱在堆积体的影响下有炸而不倒的风险。而将爆破切口高度提高至5.6 m,同时开凿6.09 m宽、8 m高的超大拱形导向窗的方案能够确保烟囱整体倒塌。此外,为确保拆除爆破良好,提出了采用机械清除爆破切口周边内衬,并在爆破切口及煤气管道表面覆盖由安全网、铁丝网、土工格栅等多种复合材料组成的柔性防护层的辅助措施。实际拆除爆破结果表明:切口起爆后烟囱倒塌过程平稳顺利,数值模拟结果与实际情况较为吻合,且倒塌后烟囱根部筒壁与地面间空隙被堆积物体完全填充,临近煤气管道未出现损害。此外,开凿超大拱形导向窗不仅实现了对砌体堆积的疏导,还能够大大减少装药、防护工作量,该优化方案可为类似烟囱的爆破拆除提供参考。

Aiming at the blasting demolition problems of a 180 m reinforced concrete chimney in Wuhan Iron and Steel plant,which contains a herringbone large volume lining and an adjacent gas pipe,the feasibility of the opti-mization scheme of"digging large arched guide window and raising blasting incision"was demonstrated by the AN-SYS/LS-DYNA finite element software.The calculation results show that the collapse and accumulation speed of the inner lining is obviously greater than the closing speed of the blasting incision after it is generated.Meanwhile,the chimney may not be topple over under the influence of the accumulation body by using a general directional dumping scheme.However,the chimney will collapse by raising the height of blasting incision to 5.6 m and digging a large arched guide window which is 6.09 m wide and 8 m high.In addition,to ensure a good effect of blasting demolition,the auxiliary measures of mechanically removing the lining around the blasting incision and covering the surface of the blasting incision and gas pipeline with flexible protective layers composed of safety nets,barbed wires,geogrids and other composite materials were put forward.The actual demolition blasting results show that the chimney collapse process is smooth after the incision detonation,and the numerical simulation results are in good agreement with the actual situation.At the same time,the gap between the chimney root cylinder wall and the ground is filled with the accumulated objects after the collapse,and there is no damage to the adjacent gas pipe.Besides,the excavation of the oversized arched guide window not only realizes the relief of the accumulation materials,but also greatly reduces the workload of charging and protection.