This paper investigates the stability of the Generalised-α time integration method (the CH method) for a fully coupled solid-pore fluid formulation. Theoretical stability conditions are derived, which are shown to simplify to the existing ones of the CH method for the one-phase formulation when the solid-fluid coupling is ignored. Finite Element (FE) analyses considering a range of loading conditions are conducted to validate the analytically derived stability condition, showing that the

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... al results are in agreement with the theoretical investigation. The CH method is a generalisation of a number of other time integration schemes and hence the derived stability conditions are relevant for most of the commonly utilised time integration methods for fully coupled two-phase formulation.