大型非锚固变壁厚外浮顶原油储罐的应力测试

Stress testing on large-scale unanchored tapered oil storage tanks with external floating roof

大型原油储罐多为非锚固变壁厚结构,在液压作用下,地基沉降会引起底板边缘板翘曲及壁厚变化处的应力波动等复杂现象。为了研究大型储罐受载后各圈壁板、底板的应力大小及其分布规律,采用电阻应变测量技术对水压试验中10×10~4 m^3的外浮顶原油储罐(直径80 m、罐高21.8 m)进行现场应力测试,得到储罐底板及壁板的应力数据,分析储罐关键部位的应力水平、分布特征及其原因。结果表明:在最高液位下,储罐底板主要表现为径向弯曲应力;储罐壁板根部主要为轴向弯曲应力,随测点高度升高,罐壁在水压作用下发生膨胀变形,主要表现为环向薄膜应力。该研究结果为储罐运行的安全评定提供了参考依据。

Large-scale oil storage tanks are mostly unanchored and tapered, so complicated phenomena will emerge on the tanks as the foundation settles under hydraulic pressure, such as the warping of edge plate at the bottom and the stress fluctuation at the shell thickness changing zones. To investigate the level and distribution of stress at the shell and bottom board of large-scale loaded tanks, field stress testing was performed on an external-floating-roof oil storage tank with a capacity of 10×104 m3 （D=80 m, H=21.8 m） during the hydrostatic testing by using the resistance strain measurement technology. Based on the stress measured at the tank shell and bottom board, the levels and distribution characteristics of stress at key parts of storage tank and their causes were analyzed. It is indicated that radial bending stress is dominant at the tank bottom while the liquid level is the highest. Axial bending stress is dominant at the root of tank shell. With the rising of measurement point height, the tank shell suffers swelling deformation under the effect of hydraulic pressure, and the circumferential membrane stress is dominant. The research results can be used as the reference for the operation safety assessment of storage tanks.