3D FEM Analysis of Effects on Adjacent Pipelines by Pit Excavation

Pit excavation influences the stress and deformation of adjacent underground pipelines seriously. On the base of former study, the project was analyzed with the aid of general finite element soft ABAQUS, in which the interactive action of soil with pipeline and pit protection structure were taken into account. Wall-soil friction and pipeline-soil friction contact were used. The influence on adjacent pipelines of pit excavation was analyzed. The laws of deformation and the stress were gained. The results showed that the horizontal displacement was much bigger than the vertical displacement, and the pipeline would lift at the end close to the symmetric plane and fall at the other end. The displacement would decrease with the increment of the distance between pit and pipelines. The laws of influence of the pipeline's embedment and wall-soil friction were similar, while the latter's influence was greater than the former's. The influence on horizontal displacement aroused by wall-soil friction was greater. The principle tensile stress mainly aroused by the pipeline's horizontal displacement would cause tension fracture. The sections of the pipeline around the area of the end and the middle of the pit were dangerous, which should be particularly protected.