A new apparatus for centrifuge modelling of 3D braced excavations
A new apparatus for centrifuge modelling of 3D braced excavations
Continuous urbanisation has placed ever-increasing demands on transport networks, requiring urban planners and engineers to effectively utilise available underground space. The construction phase of underground infrastructure is typically the most disruptive, as it often entails a significant item of temporary works a large braced excavation. This comprises embedded retaining walls supported by a system of temporary props spanning across the excavation as excavation proceeds in a top-down manner. Key design issues for such works are the prediction of ground movements adjacent to the excavation, where neighbouring buildings are often located, and propping forces. While extensive research has focused on 2D modelling of excavations, accounting for 3D effects, which is essential for investigating behaviour at excavation corners, is rarely considered. Improved understanding of corner behaviour and the influences of soil behaviour, system stiffness and propping arrangement could lead to more cost-effective propping strategies, a less congested working volume within the excavation, and improved prediction of ground movements adjacent to corners. This paper first reviews existing techniques for modelling braced excavations. Subsequently, the design of a new apparatus for 3D centrifuge modelling of braced excavations utilising a trapdoor approach is presented and design criteria including excavation geometry, boundary effects, wall design, and propping layouts are discussed. The new concept incorporates soil-structure interaction for a complete 3D box and enables controlled stress reduction within the excavation in a top-down manner around various propping configurations. This will provide data for validation of future numerical and analytical modelling approaches.
A. S. N. Alagha; Jonathan A. Knappett; Mike Brown; Charles Edward Augarde; William Coombs; Alexandros Petalas; Mao Ouyang
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Special Session 1: Physical modelling – from Practice/Industry to Academia
https://doi.org/10.53243/ICPMG2026-458