Numerical analysis of strain holding test considering partial drainage and soil rheology

Strain holding test(SHT),part of self-boring pressuremeter test,is one of the most effective in-situ tests in determining horizontal coefficient of consolidation(ch).However,the commonly used interpretation method proposed by Clarke et al for deriving ch from SHT results can lead to an inaccurate estimation of ch due to simplified assumptions.Numerical analysis of SHT in saturated clay is carried out to illuminate the applied conditions of Clarke consolidation curve(after Randolph and Wroth) based on elastic-perfectly plastic Drucker-Prager model.And the values of time factor T50 provided by Clarke el al to estimate ch are modified in view of the effects of soil permeability and strain rate on partial drainage during cavity expansion.Moreover,analysis is performed considering the soil rheology during SHT based on the coupling Drucker-Prager and creep model to investigate the influence of soil rheology during SHT on the decay of excess pore pressure.It is concluded that for the lower permeability,the soil rheology has significant impact on the dissipation of excess pore pressure,and that ignoring the soil rheology during SHT will overestimate ch by several times,and even tens of times for some conditions.