立式圆柱形油罐基础形状和罐底板寿命

Shape of Foundation and Service Life of Bottom Plates for Vertical Cylindral Tanks.

目前国内立式圆柱形油罐基础顶面的形状均为正圆锥形,即罐基础中心高、四周低,目的是当罐基础沉降稳定后仍能保持这个形状,便于排除油罐底面上的积水。通过对罐基础发生沉降后罐底板实际形状的分析研究,认为中心高、四周低的形状在基础沉降稳定后将不能保持,基础发生沉降时,罐底板的面积大于油罐基础的表面积,且底板在罐壁板和边缘板的约束下,底板外部板的环向拉抻变形很小,使罐底板不得不因基础沉降而发生凹凸变形,这种凹凸变形将无法保证原设计排水坑处于罐基础的最低点,造成排水困难。底板上的沉积水分散于各个凹坑中,给凹坑中的底板腐蚀创造了条件,加速了底板腐蚀。为了防止罐基础沉降前后的形状改变对底板的腐蚀,建议参考国外中心低、四周高的罐基础形状,以一个新观念去重新设计罐基础。

The top surfaces of foundations for vertical cylindral tanks in China are of cone shape, (i. e. high in center and low all around) ,the reason for that is to maintain this shape after foundation settlement and to be convenient for the drainage of deposited water. On the basis of the analysis on the actual shapes of the bottom plates after foundation settlement, the author holds that the designed cone shape will not be maintained after foundation settlement. During settlement,the area of bottom plates will become larger than that of tank foundation,and the circumferential tensile deformation of the outer bottom plates will be quite small due to the restrains from shell plates and edge plates. Under these circumstances, bottom plates deform unevenly,and the designed drains move off the lowest position. So the result is that the deposited water will be difficult to be drained,and the corrosion to bottom plates accelerated. This paper suggests that new tank foundation shape (i. e. low in center and high all around) shall be designed to prevent bottom plates from corrosion resulted from foundation deformation after settlement.