On some uncertainties related to static liquefaction triggering assessments

Abstract

Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering (SLT) have been made. These include applications of critical-state-based models in a stress–deformation framework to identify if in situ conditions are approaching a level where SLT could occur. However, several important uncertainties remain. In this work, three of these uncertainties (geostatic stress ratio K0, intermediate principal stress ratio and principal stress angle from vertical) were investigated, along with their effects (both independently and in conjunction) on the identification of SLT and slope failure. These uncertainties were examined through a series of numerical analyses of an idealised TSF. Various values of K0 were used to examine their effect on SLT, while different approaches were taken to assess the potential effects of the intermediate principal stress ratio and the principal stress angle from vertical on instability. This work revealed that the current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo SLT. Experimental and in situ test programmes that may be useful in reducing this uncertainty are outlined.