Abstract

Rocking foundations reduce seismic force demand through controlled uplift and rotation, but their application remains limited by uncertainty in residual settlement and recentring capacity. Grouting is often employed to reduce these serviceability concerns, yet uncertainty in the geometry of the improvement and seismic demand constrains confident adoption. This paper examines whether strength- and serviceability-related responses of jet-grouted rocking foundations exhibit comparable epistemic uncertainty when motion amplitude and grouting layout are represented by bounded Random Set inputs. A sparse deterministic response database was generated using three-dimensional finite-difference modelling for isolated columns, directional walls, and intersecting walls beneath a 3 × 3 m2 foundation supporting a bridge-pier-type structure. The grouting layout was represented by a directional stiffness isotropy index. Motion demand was represented through bounded peak ground acceleration intervals. The deterministic results indicate that walls aligned with the excitation direction provide greater settlement reduction and energy dissipation than isolated columns or perpendicular walls. Variation in the depth of intersecting walls further reveals a trade-off between settlement reduction and recentring capacity. Random Set propagation was then used to construct uncertainty bounds for maximum moment, residual settlement, and recentring ratio. The results show that moment demand is comparatively well constrained, whereas serviceability indicators exhibit wider epistemic uncertainty.

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