商合杭铁路芜湖长江大桥主桥3号墩水下基坑爆破施工技术

针对商合杭铁路芜湖长江大桥水下基坑爆破施工中爆破区域地质条件多变、航道情况复杂、流域水位高、水流急等众多施工技术难题,通过现场实验和专家评估,决定采用水下深孔微差爆破技术。运用钢管排架方案下放套管,基坑底面标高需超深0.4 m,爆区内炮孔采用梅花形布设,纵横向间排距均为2.0 m;炮孔使用水胶炸药装药,设计炸药单耗2.0~2.1 kg/m3,单孔药量48~88 kg,并对装药结构进行抗压处理;并通过六缆定位法,实现钻爆船、清渣船与运渣船协同作业。

Underwater Blasting Construction Techniques for No.3 Pier Foundation Pit of Main Bridge of Wuhu Changjiang River Bridge of Shangqiu-Hefei-Hangzhou Railway

For the construction technology problems of Wuhu Yangtze river bridge of the Shangqiu-Hefei-Hang-zhou railway,there are some complex conditions including engineering geology and channel,high water level and ur-gent flow.Through the field experiment and expert evaluation,underwater deep hole millisecond blasting technology was adopted.The casing was down-transferred by the steel pipe bent frame plan.The bottom of the pit height was de-signed to be over-deep 0.4 m,blasting area with plum blossom-shaped layout,vertical and horizontal spacing 2.0 m. Water glue explosive was designed with consumption 2.0～2.1 kg／m3,single hole explosive amount of 48～88 kg and the charge structure subjected to compression treatment.The co-operation of the blasting ship,the slag cleaning vessel and the slag transporting ship were realized by the six cables positioning method.