Thrust Restraint of Buried Pipelines

The paper presents a discussion on the behavior of a pipeline near a bend with and without a thrust block when subjected to internal pressure, including the Poisson effect, and thermal loading resulting from the differences between the operation and construction environments. The paper presents load combinations that must be considered in analysis and design of thrust blocks and pipelines with tied joints near bends applicable to concrete, metallic, fiberglass, and plastic pipeline materials. The analysis of thrust effects is performed using FEA of pipe-soil interaction near the bends. The results show that the longitudinal strains resulting from the Poisson effect of internal pressure and thermal loads may result in significant differences in loads on thrust blocks and stresses in bends. The Poisson effect of pressure in the pipeline decreases the stresses in the pipe wall and the load on thrust blocks. Thermal loads may increase or decrease the loads on thrust blocks and stresses in the pipe wall. The case of a fiberglass pipe with restrained joints, which was analyzed, is discussed in detail.