Numerical Analysis of the Stress Distribution in Symmetrical Backfilled Trenches with Inclined Walls: Fid-Bau Portal

Numerical Analysis of the Stress Distribution in Symmetrical Backfilled Trenches with Inclined Walls

Li, Li / Aubertin, Michel

Abstract Backfilled trenches are commonly used for municipal and industrial services such as gas, drinking water and sewers. Their design involves the determination of the stresses imposed due to the fill material, which requires a good understanding of the interaction between the backfill and abutment walls. In practice, such stresses (or loads) are often estimated using an analytical solution proposed by Marston, based on the arching theory with a constant earth pressure coefficient. However, a number of influencing factors are neglected when using this approach. This paper investigates the effect of key factors on the stress distribution in symmetrical backfilled trenches with inclined walls, through a series of numerical simulations. The results presented here illustrate how the vertical and horizontal stresses distribution is affected by the trench geometry, including its width and wall inclination, and by the backfill properties. Results from this numerical investigation show that the application of the basic Marston’s solution can lead to a significant underestimation of the stresses, particularly in the lower part of a trench. The magnitude of the undervaluation is more pronounced when the stiffness contrast between the backfill and wall material is small. The simulations further indicate that the earth pressure coefficient K varies with depth and wall inclination, indicating that using a constant value of K may not be appropriate for trenches with inclined walls. A discussion follows on the significance and limitations of this work, and on additional factors that can influence the stress state in backfilled trenches.