2.3. Model dimensions
When buried pipes are in service, pipes are surrounded by soil, and external load is transferred to pipes through the soil. Deformation will occur on the pipe due to the loading, and the soil is squeezed, which makes it becomes deformed too. Thus, in the simulation process, soil around the pipe should be taken into account. At the same time, on the premise of accuracy, computations should be reduced as little as possible. On the LY2811376 of the principle mentioned above, the dimension of the finite element model is taken as 10 m × 3 m × 1.8 m (length (L) × width (W) × height (H)). There are three sections in the axial direction of the pipe, subsidence area (5 m), transition section (1 m) and non-subsidence area (4 m). The outside diameter of the PE pipe is DN110, which is commonly used in urban gas transportation systems, with SDR11 (Standard Dimension Ratio), and its thickness is 10 mm.