V型钢筋混凝土结构拱桥的控制爆破拆除

Controlled Explosive Demolition of V Rigid Arch Reinforced Concrete Bridge

为了拆除一座斜拱断面尺寸大、配筋高、周边环境复杂的长149.22 m连续钢构的V型拱桥,研究其控制爆破拆除方案及相关爆破参数。针对桥梁的特点,采取了对桥梁的斜拱下部及其上方箱型梁进行预拆除后再爆破的原地坍塌拆除方案。下部斜拱处爆破切口的断面宽度4.02～5.75 m、厚度1.8 m,切口长度6 m,采用水平布孔;上部箱梁切口的腹板断面宽度0.5～0.9 m、高度1.7 m,切口长度3 m,采用垂直布孔;所有炮孔均采用分段装药结构;下部切口间的起爆时差0.5 s,上、下切口的起爆延时0.5～0.7 s;爆破切口区域进行覆盖防护和近体遮挡防护,并在爆破切口下方堆砌松软土埂以减弱桥体坍塌的触地冲击振动。爆破效果良好,有效控制了爆破飞石和桥体坍塌引起的振动效应等危害。

In order to demolish a V rigid arch bridge with the length 149.22 m,due to the large section size and high reinforce as well as the complex surroundings,a scheme of controlled explosive demolition and blasting parameters were studied.According to the characteristic of the bridge,the collapse demolition scheme was designed as dividing the bottom of oblique arch and the box beam in advance.For the inclined arch,the blast cut section was designed as 4.02~5.75 m wide,1.8m thick and 6 m long,where the blast hole was horizontal.For the box beam,the blast cut section of was 0.5~0.9 m wide,1.7 m high and 3 m long,where the blast hole was vertical.The divided charging construction was used in all blast holes.The delay interval between the blast cut of oblique arch was 0.5 s and which between the blast cut of oblique arch and one of box beam was 0.5~0.7 s.The overlay defense and shield defense were all used in the blast cut area.Moreover,the light soil dams were stacked under the blast cut area so as to weaken the vibration caused by touchdown of bridge collapse.The adverse effects of blasting such as blasting flying and blasting vibration were effectively controlled.