中文摘要：

针对直埋热水供热管道三通受力的复杂性，基于土弹簧模型建立了热-力耦合有限元模型，分析了直埋三通应力的主要影响因素，并给出了简化三通接管长度的热-力耦合有限元模型．建模中管土相互作用考虑了介质本身的重量和覆土重力等的作用，三通管段的边界条件施加在主管和支管端头．结果表明，直埋三通在温升作用下，相贯区峰值应力较大；直埋三通的二次应力随温升、管道壁厚、支管管径、主管过渡段长度变化，而受内压影响较小；地面荷载作用使三通最大当量应力减小，对三通起保护作用．该结果旨在为直埋管道的安全性提供帮助．

英文摘要：

To study the complicated stress characteristics of T- joints in directly buried heating pipelines, a thermal-mechanicalcoupled finite element model was constructed using the soil spring model. The main affecting factors on stress distribution of directlyburied T- joints were analyzed. A thermal-mechanical coupled finite element model for T- joints with reduced straight pipe lengthswas given. The weights of thermal medium and covering soil were considered in the pipe-soil interaction of the model. The boundaryconditions were applied to the ends of the main pipes and the branch. The results indicate that the junction area of buried T- jointsbears peak stress with high value due to temperature rise. The secondary stress varies with temperature rise, pipe wall thickness,branch diameter and the length of partly restrained section. The internal pressure has little effect on the secondary stress of T- joints.The ground load, which decreases the maximum equivalent stress of buried tee joint, is benefit to the buried pipelines. The findingsof this article aim to provide aid for security analysis on buried pipelines.