On the rheological characterisation of liquefied sands through the dam‐breaking test

Abstract

Summary This paper concerns the rheological characterisation of liquefied sands as non‐Newtonian Bingham fluids. For this purpose, dam‐breaking laboratory tests are often executed and interpreted, offering a viable option to identify the properties of fluidised water‐soil mixtures. However, limited attention has been devoted so far to clarify what variables and measurements would allow unambiguous calibration of Bingham parameters, namely, the viscosity η and the yield stress τy. The numerical results of parametric studies based on the particle finite element method (PFEM) are critically inspected to gain deeper insight into the problem. First, it is confirmed that multiple η − τy pairs may reproduce the same experimental evidence when formed by only one measurement—usually, the post–dam‐breaking displacement of the bottom toe (tip) of the liquefied mass. Then, two alternative procedures are proposed for unambiguous identification of both η and τy: one is based on monitoring the evolving aspect ratio of the fluid mass during free, gravity‐driven flow; the other relies on a slightly different dam‐breaking test, also including impact against a rigid obstacle. In particular, the latter approach reduces the relevant duration of the test, reducing the possible influence of reconsolidation effects on the calibration of rheological parameters.

A State of the Art Review of the Particle Finite Element Method (PFEM)

“…17to represent the behaviour of frictional viscoplastic materials. This model has been extensively used in the PFEM framework to simulate the flow of soil or granular material in [22,61,117].…”

Lagrangian Differencing Dynamics for Time-Independent Non-Newtonian Materials

“…The analyses given in Basic et al [37] have shown that the types of problems described using Equations ( 17) and ( 19) reach second-order convergence for Dirichlet, Neumann and mixed-boundary conditions. Equation (19), along with the no-slip boundary condition, can be straightforwardly solved using an iterative matrix-free solver.…”

“…Two-and three-dimensional simulations were carried out using the PFEM, and solid structures were simulated by employing FEM. Della Vecchia et al [19] investigated Bingham fluids, specifically the rheological characteristics of water-soil mixtures on the dam-break tests. The numerical analysis examined the viscosity and yield stress of the Bingham model based on the CFD-PFEM parametric studies.…”

CFD-Based Framework for Analysis of Soil–Pipeline Interaction in Reconsolidating Liquefied Sand

“…According to Montassar and de Buhan (2013), "obtained data for the equivalent Newtonian viscosity coefficients range between 10 −1 and 10 7 Pa•s". Not only 'intrinsic' factors (e.g., soil mineralogy, porosity, and grain size distribution) contribute to such variability, but also the lack of standard procedures for the interpretation of laboratory tests (Della Vecchia et al, 2019).…”