Two-mechanism probabilistic framework for excavation-induced settlement and tube-house fragility: dewatering consolidation at Hanoi Metro Station S11

Confined-aquifer dewatering during deep cut-and-cover excavation can equal or exceed wall-deflection settlement, yet deterministic design routinely omits it. This paper presents a probabilistic two-mechanism framework for Station S11 on Hanoi Metro Line 3, in the historic centre of the capital, coupling the Hsieh–Ou spandrel profile with an empirical linear-drawdown consolidation model. Monte Carlo simulation (N = 100,000) propagates parameter uncertainty into distributions of settlement and angular distortion for adjacent tube-houses. Dewatering-related parameters dominate the variance in angular distortion, so under the adopted linear-drawdown representation groundwater control emerges as a primary lever for risk reduction. Model-form uncertainty, rather than parameter uncertainty, drives the predicted risk: the probability of angular distortion exceeding 1/500 rad ranges from 0.01% to 42.5% depending on the dewatering-attenuation assumption. Calibrated in the near field (d ≤ 18 m), the model gives a conservative estimate of angular distortion; in the far field it underestimates settlement magnitude (validation bias −9.8 mm) owing to unmodelled barrier effects, so far-field settlements are reported only as lower bounds. The framework offers a practical basis for risk-averse assessment of excavation impacts on buildings in soft-soil urban environments.