在直埋热力管网中，直管段占有相当大的比重，合理地进行直管段的强度设计对整个热网安全经济地运行具有重要意义。在直管段的强度设计中，应采取一定的措施，防止直管段中的管道出现下列破坏：温度变化产生的应力变化导致的循环塑性变形；运行温度下高的轴向压力导致的管线整? In the directly buried heat pipe network, the straight pipe section occupies a considerable proportion, and reasonably designing the strength of the straight pipe section is of great significance to the safe and economic operation of the entire heat network. In the strength design of straight pipe sections, certain measures should be taken to prevent the following damages to the pipes in straight pipe sections: Cyclic plastic deformation caused by stress changes due to temperature changes;