大型金属罐基础环梁开裂事故的理论分析及加固研究

Theoretical Analysis and Reinforcement Study of the Foundation Ring Beam Cracking Accident for the Large Metal Tanks

位于广西南宁市某工业区内的4个大型液化罐在新建成不久后,调试注水期间,沿罐体基础环梁出现了大量的竖向裂缝,且钢罐与环梁发生了较大角度的翘曲变形,严重影响了企业的后续生产。为了研究此类工程事故发生的原因,通过现场检测获取液化罐与基础环梁的各项性能指标,分析了各罐环梁裂缝状况、混凝土的外观情况和强度以及储罐垂直度等宏观性能;并以具有代表性的1号罐为例,运用数值模拟技术以及传统理论方法进行5种工况组合下的承载力验算。研究结果表明:事故主要由两个方面的原因所致:①在地面标高以上部分的环梁承受其内填砂挤推而开裂;②环梁内填砂不密实,钢罐注水时引起底部钢板的挠曲变形从而挤推填砂,同时又由于施工质量存在缺陷引发罐体底部与环梁发生翘曲,翘曲变形又加大对填砂侧推,交互影响下使得环梁横截面的环向拉应力过大而产生竖向裂缝。最后提出了采取的加固方案,采用填砂法和外加预应力加固法综合加固基础环梁。研究成果可为同类工程的科学研究和设计提供参考。

Located at an industrial zone of Nanning, Guangxi, there are four liquefaction tanks which were built newly. When they were poured into water for debugging, their foundation ring beams appeared a lot of vertical cracks, and steel tanks warped from each ring beam with a large angle. So the company＇s follow-up production seriously affected. In order to research the cause of such construction accident, the performance indicators of liquefaction tanks and foundation ring beams are obtained by on-site inspection, and at the same time, ring beam cracks＇ situation, appearance and strength of ooncrete and tank vertical degree are analyzed. The No. 1 tank is .selected as a typical example to calculate. The numerical simulation technique and traditional theoretical approaches are used to analyze five different cases for bearing capacity. The results show that there are two main causes in this accident. One is that the ring wall above the ground elevation is thrust by the inner sand. The other is that as the ring beam is not filled with dense sand, the bottom ＂steel fiat had a bend deflection when it is poured into water, and at the same time steel tanks warped from ring beam because of bad construction quality. Under the influence of interaction, the hoop tensile stress of ring beam cross-section is over its tensile strength to crack. At last, the reinforcement program is put forward. Sand filling method and plus prestressed reinforcement method are advised. The research results can provide a reference to the scientific research and design of similar projects.