Bowing of a Pipeline from Longitudinal Compressive Stress Induced by Ground Movement

This paper concerns a case history of a buried gas transmission line which had been exposed to mine subsidence ground movements. The mine subsidence movements were the result of longwalling ore at a depth of approximately 1,600 ft. As the extraction of the ore progressed, the stress in the monitored pipeline worsened and was approaching unacceptable levels. The excessive pipe compression resulted when it was exposed to the compression zone of the subsidence basin created by the mining. In order to relieve ground movement induced compressive stress, the line was uncovered. As more of the pipeline was exposed, the pipe abruptly bowed in the trench excavation. An analysis of this pipe deformation which was performed is provided in this paper. This bowing/buckling phenomenon is not specifically covered in the ASME code. Also, discussed in this paper are ways to mitigate this pipe deformation or upheaval buckling from occurring.