油田上使用着的各种井架,绝大多数都是由许多截面尺寸远小于其长度的细长杆体所组成的一种特殊的杆体体系结构,即塔桅钢结构。通常,井架在工作过程(包括其起放过程)中发生的重大事故,往往都是由于井架丧失稳定(简称失稳)。井架的失稳一般包括倾倒失稳和弹性失稳两种类型。前者是整个井架作为一个刚体在外力作用下,不能保持其原来的位置而倾倒。至于后者,则是整个井架或其中个别杆 The vast majority of derricks that are used on the field are made of a special rod-body structure consisting of many elongated rods of much smaller cross-sectional dimensions than their length, namely tower mast steel structures. In general, the major accidents that occur in the derrick during its operation (including its release process) are often caused by the loss of stability of the derrick. Derrick instability generally includes two types of dumping instability and elastic instability. The former is the whole derrick as a rigid body in the external force, can not maintain its original position and dumping. As for the latter, it is the entire derrick or individual rods