一、引言长距离输油管道在平面走向改变处和竖向坡度、坡向变化处,都会出现大量折点,在地形复杂的山区,更是不计其数。在这些地方将管子组接成直管段,利用管子的弹性,用外力(平面折点)或自重(竖向折点)使管道冷弯成所要求的大曲线半径(一 I. INTRODUCTION Long-distance oil pipelines will have a large number of breakpoints at the change of the plane direction and the vertical gradient and slope change. In mountainous areas with complex terrain, it is even more numerous. In these places, the pipes are grouped into straight pipe sections and the pipe is cold-bent to the required large radius of the curve by means of external force (plane break) or self-weight (vertical break), using the elasticity of the pipe