+40m高位切口定向爆破拆除一座150m和两座210m高烟囱

Directional Explosive Demolition of one 150m and Two 210m High Chimney by+40m High Location Cutting

介绍了1座150 m高2座210 m高烟囱因倒塌空间不足而采用的高位切口爆破拆除工程实例。采用+40 m高位切口成功爆破拆除3座高大烟囱,待爆破烟囱均采用正梯形爆破切口,分三次实施定向倾倒爆破,采用孔内、孔外相结合的延时起爆技术,在烟囱倒塌方向铺设缓冲层、堆设防冲堤、开挖减震沟,爆破切口采用密目网、土工格栅覆盖防护等防护措施,通过测振仪对爆破振动进行监测,爆破飞散物和触地振动均控制在安全允许范围内,未对周围建(构)筑物造成损害。爆破效果表明:采用高位切口爆破能有效地解决倒塌空间局限的问题,且避免烟囱底部积灰平台、烟道口等因素影响倒塌方向,减少触地飞溅物的距离,降低触地振动和爆破振动;将钻孔钻透烟囱混凝土壁,打入内衬和隔热层中进行爆破,能够有效地处理烟囱内衬;钻孔取芯机预处理定向窗与导向窗,有利于减少用药量,有利于切口破碎,确保切口顺利闭合,有利于确保倾倒方向的精确性,对于同类型复杂环境下烟囱定向拆除具有一定的参考价值。

One 150 m high and two 210 m high chimneys have been successfully demolished by blasting with 40 m high trapezoidal cuts in an insufficient collapse space.Directional collapse blasting was carried out for three times by combining in-hole and out-hole delays.The protection measures included laying a cushion in the direction of chimney collapse,piling up an impingement dike,excavating a vibration damping ditch,putting a dense screen at the blasting cut and overlaying geogrids.Blast vibrations monitoring proved that the flying objects and blast vibrations were both controlled within the safety allowable range and no damage was caused to surrounding structures.The blasting effect shows that high blasting cuts can effectively solve the problem of limited collapse space,and avoid the influence of factors such as soot platform at the bottom of the chimney and flue entrance on the collapse direction.At the same time,this technique can also limit the flyting distance of the splash on the ground and reduce the ground contact vibration and blast vibration.In addition,the chimney lining can be effectively treated by blasting boreholes through the concrete walls of the chimney into the lining and insulation layer.Another good practice is to pretreat the directional windows and guide windows by a drilling and coring machine,which can reduce explosive charge and promote the breakage of the blasting cuts so as to ensure the exact direction of collapse.