Numerical Analysis of Submerged Soil Behavior in Pipeline Installations Crossing Rivers

The paper investigates the pattern of soil stress around a pipeline installed under the river using a nonlinear three-dimensional finite element method (FEM). This study compares von Mises soil stresses occurring in native soil adjacent to river crossing pipeline between traditional open trench (OT) and horizontal directional drilling (HDD) pipe installation methods. The Mohr-Coulomb theory is utilized to describe soil behavior in the finite element models. The entire model is assumed to be elastoplastic. The whole research considers saturated native soil one month after construction. Additionally, design parameters (i.e., depth of cover and annular space) in HDD method are examined to understand their influence on soil stress occurring around original soil. The paper investigates how critical design parameters (i.e., density and diameter) in the annular space affect the pattern of maximum von Mises soil stresses occurring in native soil adjacent to pipeline installed under the river. Finally this study found that when the OT method is used for pipeline crossing under the river, stress occurring in the soil cover is greater than when the HDD method is used. In addition, the diameter of the annular space in HDD method could impact on total soil stress occurring in the soil overburden.