短补偿臂“Z”形供热直埋弯管的应力分析

Stress Analysis of Z-shape Elbow with Short Compensated Arm in Directly Buried Heat-supply Pipeline

《城镇供热直埋热水管道技术规程》CJJ/81-2013规定,Z形弯管补偿器补偿臂长不应小于2倍管道的弹性臂长。工程实践中由于道路等条件限制,绝大部分Z形弯管补偿臂长小于2倍管道的弹性臂长。这样规定,使得相当一部分Z形弯管不但不能用作Z形弯管补偿器使用而且还要人为安装补偿器或固定墩进行保护,既增加了工程造价、延长了施工周期、还降低了供热运行的安全性。针对这一问题,应用ANSYS10.0有限元分析软件,对DN150-DN500供热直埋管道补偿臂长小于2倍管道弹性臂长的＂Z＂形弯管进行了数值模拟。得出了补偿臂长在1.25-2倍管道弹性臂长的＂Z＂形弯管,SINT应力值更小,更适宜用作Z形弯管补偿器使用。这一结论填补了CJJ/81-2013中,对于管径在DN150-DN500、补偿臂长在1.25-2倍管道弹性臂长的＂Z＂形弯管,用作Z形弯管补偿器使用的空白。

Regulation prescribes that the compensated arm length of Z-shape compensated elbow should not be less than double elastic arm length. However, in engineering practice, most compensated arm length of Z-shape compen- sated elbow is less than double elastic arm length due to road conditions, and so on. It makes a part of Z-shape el- bows cannot be used as compensators, and compensators and fixed piers must be installed to protect the pipeline by people ,thus both increasing the engineering cost, extending construction period, and also reducing the safety of heating operation. Therefore, the Z-shape elbow,whose pipe diameter is DN150 to DNS00 and the compensated arm length is less than double elastic arm length ,was simulated by finite element analysis software ANSYS10.0. For the thermal stress values smaller than the regulation, the Z-shape elbow with the compensated arm length 1.25 to 2 times of elastic arm length is more suitable as a Z-shape bend compensator. It is concluded that the Z-shape elbow with the pipe diameter DN150 to DNS00 and the compensated arm length 1.25 to 2 times of elastic arm length can be used as Z-shape compensator. That conclusion fills the gap of the regulation.