Cantilever steel tubular pile wall embedded in soft rock subjected to sequential loadings

• Published in: International journal of physical modelling in geotechnics 2024-11, p.1-63
• Main Authors: Shafi, S M, Takemura, Jiro, Kunasegaram, Vijayakanthan
• Format: Article
• Language: English
• ISSN: 1346-213X; 2042-6550
• DOI: 10.1680/jphmg.24.00007

An attempt has been made to study the mechanical behaviour of a cantilever-type large-diameter steel tubular pile retaining wall embedded in soft rock subjected to sequential dynamic and static loadings by centrifuge modelling. A centrifuge model is developed to simulate sequential dynamic and static loadings with clear boundary conditions, aiming to comprehend the mechanical response of a cantilever-type retaining wall embedded into the soft rock. The model wall was made of steel tubular piles with a 2m diameter and 25mm thickness in a prototype scale under 50g. Wall retained height (H) and embedment depth (d r ) into model soft rock (q u =1.4MPa) were 12m and 3m, respectively. Sequential loadings were applied to the model: firstly, dynamic loadings by sinusoidal input accelerations to the wall with dry retained sand; secondly, static loading by the rising water level in the retained sand; and thirdly, dynamic loadings in the wet sand condition. It was found that the resilience of the wall created by the confinement of soft rock during the dynamic loading is a critical factor that controls the earth pressure and the dynamic and residual displacements of the wall, both during and after the dynamic loading and the static loading. Due to the resilience effect, an effective earth pressure ratio of more than the design active or even an at-rest pressure coefficient could be expected, especially after dynamic loading. However, A slight wall movement in the static loading and wall creep displacement after dynamic loading could reduce this resilience effect. Secured rock confinement could be ensured for the displacement over 2%H caused by the sequential loadings.