Strength analysis of buried elbow under working load based on contact element

As a common structural element of long-distance pipeline, buried elbow may easily fail under external load. With the non-linear finite element method (FEM), a numerical model is built for stress analysis, with pipeline simulated by shell elements, soil simulated by solid elements, and interaction between elbow and soil simulated by contact elements. Through calculation and comparison of stresses under different characteristic parameters like pipeline diameter, wall thickness, curvature radius, inclination of elbow, friction factor between pipeline and soil, and elastic modulus of soil, changes in peak stresses of the pipeline are determined, namely, higher stresses can be observed on elbows with higher pipeline diameter. Structurally, it is possible to minimize stresses on the elbow by increasing wall thicknesses, curvature radius and inclination of elbows. In addition, compacting of soil around the elbow may help to reduce the stress on elbow.