Strutted excavation in soft soil incorporating a Jet-Grout Base Slab: Analysis considering the consolidation effect

Abstract

The influence of the consolidation on astrutted excavation in soft soil is analysed usinga computer code based on the finite element method.A base jet-grout slab is considered in order to improvestability against bottom heave failure and minimize walldisplacements. The numerical model incorporates theBiot consolidation theory (coupled formulation of theflow and equilibrium equations) with soil constitutiverelations simulated by the pqh critical state model.Special emphasis is given to the analysis, during andafter the construction period, of the pore pressures, shearstresses, stress levels and displacements in the ground,as well as strut compression loads, wall displacementsand bending moments, earth pressures on the wall facesand compression loads and bending moments on the jetgroutslab.The safety factor against bottom heave is alsoevaluated from the finite element analysis consideringformulations of the critical state soil mechanics, and alsocompared to values obtained with traditional methodsthat use limit equilibrium approach and bearing capacityfundamentals.