液罐基础环墙砼开裂的理论计算及成因分析

工业储罐广泛应用于各类石油化工行业。位于广西南宁市某工业区的12个巨型酒精发酵罐在试运营阶段曾发生了基础环墙的群体性开裂,产生大量的竖向裂缝,同时钢液罐与环墙发生较大角度的翘曲,影响了企业的后续生产。为了探究此类工程事故的内在原因,通过现场检测获取发酵罐与基础环墙的各项性能指标,分析了各罐的环墙混凝土强度、裂缝状况、钢筋保护层厚度及罐体垂直度等宏观特性;并以具有代表性的1号发酵罐为例,运用计算机数值模拟以及传统理论方法进行不同工况组合下的承载力验算。分析结果表明:事故由两个方面原因所致,其一是地面标高以上部分的环墙承受填砂侧压而导致;其二是由于环墙内填砂不密实,承载时引起底部钢板的变形而挤推填砂,同时引发罐体底部与环墙发生翘曲,翘曲变形又加大侧推填砂,交互作用下使得环墙的环向拉应力过大而产生竖向裂缝。研究结果可为同类工程的科学研究和设计提供参考。

Theoretical calculation and cause analysis of the cracking of concrete foundation ring wall of liquid tanks

Industrial tanks are widely used in various petrochemical industries.Located in an industrial area in Nanning,Guangxi,the foundation ring walls of twelve newly built huge alcohol fermentation tanks were cracked massively when a trial operation began.There were many vertical cracks,together with a large angle warping between the steel tank and the ring wall,which had a negative impact on the production of the factory.In order to explore the cause of such accidents,the performance indicators,such as concrete strength,state of cracks,steel condition and its cover thickness,tank verticality,concrete surface defects and so on,were tested on site.The No.1 fermentation tank was analyzed as a typical example.Computer simulation and traditional theoretical approaches were applied to calculate the bearing capacity of different cases.It is concluded that the ring walls above the ground elevation faced lateral pressure induced by the internal sand may lead to the crack.Or it is most likely that the internal sand is not dense and when the water was injected into the steel tank,the tank was warped.This may result in the bottom steel slab to become deformed and to push the sand,leading to too much larger tensile stress in the ring walls to crack.