Numerical analysis of cylindrical cavity expansion in sand considering particle crushing and intermediate principal stress

Abstract

Considering the effects of particle crushing and intermediate principal stress on material yielding strength, the spatial mobilization plane (SMP) yielding criterion and state parameter model including a general critical state line are selected in the analysis of cylindrical cavity expansion. Meanwhile, combining Rowe’s flow rule and Bolton’s simplification to stress-dilatancy relationship to reflect soil shear dilatancy and softening behavior, this paper analyzes the problem of cylindrical cavity expansion in sand by discretizing the plastic zone, which is applicable to cavity expansions from zero initial radius and finite initial radius simultaneously and can determine stress field, strain field and limit cavity pressure. A series of comparative analyses are made with the results ignoring crushing and based on Mohr-Coulomb criterion to examine the effects of crushing as well as the coupled effects of crushing and intermediate principal stress on cavity expansion. Results indicate that crushing causes a reduction in limit cavity pressure and void ratio, and results in less stiff response in expansion curves, the amounts of which increase with initial density and mean effective stress. The consideration of crushing can weaken the effects of intermediate principal stress on expansion, while the consideration of intermediate principal stress makes crushing effects become more prominent. The limit cavity pressure can be reduced by over 40% for dense sand with high initial stress based on SMP criterion when crushing is considered.

Keywords

spatial mobilization plane (SMP) theory / particle crushing / strain-softening / discretization analysis / plastic zone

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