我厂新扩建的5000吨多层冷藏库,在做外围墙的防潮隔气层时,不慎发生火灾。从一层至四层已经吊装完毕之顶排管,经大火灼烧后,均出现有不同程度的下垂现象。下垂幅度一般达20～50毫米。但经取样化验证实,其钢材性能并未改变。对于这些烧伤的一组组双层顶管,若拟割 When the newly expanded 5,000-ton multi-storey cold storage plant of our factory was doing the moisture-proof gas barrier of the outer wall, a fire accident occurred. From the first floor to the fourth floor, the top row of pipes that have been hoisted and burned after a large fire all exhibit different degrees of sagging. The droop range is generally 20 to 50 mm. However, it has been confirmed by sampling that the properties of its steel have not changed. For these groups of burned double-layer pipe jacking, if cut