Implementation of two-phase flow models for recycled materials in embankments

¹ RDP Geotechnical Engineer, Geocomp Corporation, Acton, MA, USA, and Former Research Assistant, Center for Energy and Sustainability, California State University, Los Angeles, USA
² Graduate Research Assistant, Dept. of Civil Engineering, California State University, Los Angeles, USA
^3* Assistant Professor, Dept. of Civil Engineering, California State University, Los Angeles, USA
⁴ Undergraduate Research Assistant, Dept. of Civil Engineering, California State University, Los Angeles, USA
⁵ Professor, Dept. of Civil Engineering, California State University, Los Angeles, USA

^* Corresponding author: wkwan4@calstatela.edu

Abstract

Recycled materials like Bauxite Residue (Red Mud) and Fly Ash are prevalent in recent feasibility studies on reused materials in geotechnical engineering applications. Red Mud is a mining waste from aluminum manufacturing, and Fly Ash is a by-product of coal combustion in power plants. Nevertheless, to fully reveal the feasibility of using those materials for constructing above-ground earth structures, a better understanding of their unsaturated performance in geo-structure is essential. While some popular empirical models (e.g., van Genuchten 1980) in Soil Water Retention Curves (SWRC) are commonly used to describe soils' unsaturated conditions, those models may not apply to unique materials like Red Mud and Fly Ash. Recently, SWRC curves of both materials were acquired through the Steady-State Centrifuge (SSC) Unsaturated Flow Apparatus (UFA) procedure at Cal State LA. The experimental data were used to develop analytical models following the van Genuchten model. Using a finite-difference software (FLAC) and obtained SWRC curves, this study performed numerical simulations of embankments filled with Fly Ash and Red Mud, comparing it with an embankment filled with typical silty soil with the same dimensions and conditions. Results showed seepage flow rates for Fly Ash and Red Mud are higher when used as fill material as above-ground embankments.