Numerical Modeling of a Tiedback Wood-Lagging Wall during Excavation

Predicting the performance of tiedback soldier beam shoring walls is one of the challenges in geotechnical engineering. This paper presents the results of advanced nonlinear numerical modeling of a full-scale instrumented shoring wall. The wall was constructed in granular materials, and included one- and two-tier tiedback solider beams with wood-lagging in between them. The goals of the numerical modeling were to accurately predict the bending moments in the soldier beams, the lateral movements of the exposed height of the wall, and the ground settlements behind the wall. Staged excavation analyses were performed to more accurately include the effects of the construction sequence. The tiebacks were modeled as pre-stressed springs to account for the lock-off loads and to capture increased tieback resistance relative to wall movements. The numerical model was able to predict behavior of wall and soil settlements behind it. However, the model was unable to predict soldier beam settlements, and the data indicates that soldier beam settlement significantly impacted lateral movements and ground settlements.