A new apparatus for centrifuge modelling of 3D braced excavations

TY - CONF

T1 - A new apparatus for centrifuge modelling of 3D braced excavations

AU - Alagha, Ahmed

AU - Knappett, Jonathan

AU - Brown, Michael

AU - Augarde, Charles

AU - Coombs, William M.

AU - Petalas, Alexandros

AU - Ouyang, Mao

N1 - Conference code: 11

PY - 2026/6/8

Y1 - 2026/6/8

N2 - 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.

AB - 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.

KW - Braced Excavation

KW - Retaining walls

KW - centrifuge model simulation

U2 - 10.53243/ICPMG2026-458

DO - 10.53243/ICPMG2026-458

M3 - Paper

T2 - 11th International Conference on Physical Modelling in Geotechnics

Y2 - 8 June 2026 through 12 June 2026

ER -