Numerical study of creep in soil anchor walls - a case study

ABSTRACT

One of the fundamental unknowns in geotechnical engineering, particularly in the design and analysis of retaining walls, is creep. Traditional design approaches for anchored walls often specify a certain prestressing force in the anchors while allowing minimal wall displacement. Unfortunately, the long-term effects of creep are frequently overlooked. Over time, creep leads to increasing displacement in anchored walls, changing the loads acting on stabilizing elements and diminishing the factor of safety for excavation stability. While past research has predominantly focused on short-term behaviour in anchored and nailed walls, only limited attention has been devoted to their long-term behaviour. This study addresses the existing gap by collecting data related to the long-term behaviour of anchored walls in an excavation project. Utilizing two-dimensional finite element numerical modelling, using plane-strain analyses, the study predicts the behaviour of these walls both at the end of the excavation and five years after its completion. Long-term behaviour modelling employs a history matching approach to determine creep variables. Subsequently, the study investigates horizontal wall displacements and changes in loads within the anchors over a five-year period. Through a comparison of modelling results with field measurements, the study demonstrates the model validation in forecasting horizontal displacements at various locations and changes in loads on the anchors over time. Furthermore, the proposed method for long-term deformation calculations of excavation walls enables the anticipation of when horizontal wall displacements may surpass allowable limits. This research concludes with an examination of the evolving trends in anchor loads over time, substantiated by a combination of measurements and numerical modelling.

KEYWORDS:

• Excavation
• soil anchor wall
• displacement
• creep
• numerical modelling
• finite elements

Disclosure statement

No potential conflict of interest was reported by the author(s).