通过现场勘查、宏观检测、扫描电镜分析、金相分析、理化检测等技术手段,对塔式起重机上部结构整体翻落重大事故的发生原因进行了综合分析。结果表明,塔机回转支承的制造缺陷、越程槽处应力集中严重,导致回转支承的承载能力明显降低是事故发生的直接原因。 By means of site investigation, macro inspection, SEM, metallographic analysis, physical and chemical testing, the causes of the overall overturning of the tower crane were analyzed comprehensively. The results show that the manufacturing defects of the tower crane slewing ring and the stress concentration in the cross-flow groove are serious. As a result, the bearing capacity of the slewing ring is obviously reduced, which is the direct cause of the accident.