Development of an Online Calculation Tool for Safety Evaluation of Pipes Subjected to Ground Movements

Abstract

Underground pipelines are inevitably installed in unstable geohazard areas associated with the possible development of significant ground deformations. Under ground movement, excessive strains can be generated in the pipe wall, which poses a threat to pipeline integrity. This study aims to develop an industry-oriented calculation tool for safety evaluation of pipes subjected to ground movements induced by a variety of nature and construction-related hazards. The tool, comprised of deterministic and reliability-based analyses, is designed within MecSimCalc which is an innovative online platform for creating and sharing web-based Apps for individuals and groups. Calculation flow behind the tool is developed according to a novel method proposed based upon the finite difference method (FDM). Given grid nodes along the pipe, a large set of simultaneous finite-difference equations are constructed based on nonlinear governing differential equations of the Euler-Bernoulli beam under large deflections. The nonlinearities arising from pipe material, pipe-soil interaction, and geometry of the pipe are considered within the model. As unknowns of the finite-difference equations, the axial and lateral displacement of the pipe at each grid node can be obtained using nonlinear equation solvers. This method is utilized to predict the strain demand in the limit state function for reliability-based assessment. Applying stochastic properties for each basic parameter, the probability of failure can be calculated using Monte Carlo Simulation. Meanwhile, the program is compiled using Numba in Python and then optimized by the parallelization technique to enhance computational efficiency.