紧邻既有桥梁的大型钢筋混凝土拱桥爆破拆除

Explosive Demolition of Large Reinforced Concrete Arch Bridge Adjacent to Existing Bridges

待拆除的桥梁为大型钢筋混凝土拱桥,全长为346 m,桥面宽24 m,与紧邻既有桥梁水平间距为0.5 m。为确保紧邻既有桥梁顺利的爆破拆除,采用原地缓冲塌落控制爆破技术来确保紧邻既有桥梁安全。桥梁选取的爆破部位是桥墩、拱腿、斜撑、拱顶,由于尺寸不一,在桥墩处采用深孔爆破,在拱腿、斜撑及拱顶采用浅孔爆破。根据爆破部位的尺寸材料采用不同的爆破参数,来控制爆破有害效应。通过逐跨延时爆破网路,减小一次塌落块体质量,有效的降低了塌落振动强度。应用塌落振动公式和测振仪,来验证爆破振动强度值在安全允许范围内。采用竹排和轮胎的防护方案,有效降低了飞石距离,确保了紧邻既有桥梁的安全。

A large-scale reinforced concrete arch bridge is to be demolished,which is 346 m long and 24 m wide.There is an adjacent bridge with a horizontal distance of 0.5 m from the arch bridge.In order to ensure smooth demolition of existing bridges and the safety of the adjacent bridges,in-situ buffer collapse control blasting technology was adopted.The blasting parts are the piers,arches,strutsand vaults of the bridge.Due to the different sizes of these parts,deep hole blasting is used at the piers,and shallow hole blasting is used at the arches,braces and vaults.Besides,in order to control the blasting effect,different blasting parameters were designed according to the sizes of different parts.By delaying the blasting network on a span-by-span basis,the mass of the collapsed block is reduced,and the strength of the collapse vibration is effectively reduced.The verification by the collapse vibration formula and vibrometer shows that the blasting vibration level is within the safe allowable range.Meanwhile,the protection scheme of bamboo rafts and tires can effectively reduce the flying stone distance and ensure the safety of adjacent bridges.