An Experimental Study on the Post-Liquefaction Shear Strength of Aluminum Tailings

There have been many cases of flow failure in tailings dams triggered by liquefaction both from static and dynamic lading in the last two decades. In 2016, an aluminum tailings facility failed in China creating an environmental disaster. Currently, there is a lack of research addressing the large strain characteristics of aluminum tailings especially related to its undrained shear strength which is important since the safety of embankments against flow failure is commonly conducted by carrying out post-liquefaction stability analysis. This paper aims to estimate the post-liquefaction shear strength of aluminum tailings by means of undrained triaxial compression tests and the application of steady state theory. Furthermore, to study the effects of plasticity and mineralogy of the aluminum tailings, a mixture of several types of silica sands was prepared aiming to resemble the aluminum's coarse-fraction gradation. Results showed that quasi steady state response is predominant for aluminum tailings whereas the silica sand mixture shows steady state response at low levels of confining stress and density. Furthermore, a unique normalized undrained ratio for post-seismic stability analysis was obtained and its applicability in engineering design was evaluated.