Abstract
In this study an effective stress model for cement-treated soil is employed to carry out a systematic study on cement-treated soil slab used to control the wall displacement in excavations with thick, soft clay layers. Deterministic analyses were first conducted to assess the drainage state of the treated soil slab. These indicate that, under timescales which are representative of those in actual construction, cement-treated soil slab conditions may range from nearly undrained to drained. Random finite-element analyses also show that the global undrained and drained behaviour of the treated soil slab differ significantly. Undrained loading leads to a rapid rise in stress with strain to a peak strength with subsequent softening. Drained behaviour, on the other hand, leads to a more compliant response, which suggests that the main issue in the drained condition is likely to be large displacement, rather than complete collapse. A rational design framework for cement-treated soil slab is proposed, which explicitly considers the distribution in global behaviours of the treated soil slab. This differs from current limit state approaches which are largely based on statistical properties of the input data, such as the unconfined compressive strength of sampled cores.