Abstract

Abstract

The Synthetic Lightweight Aggregates (SLA) is a patented aggregate composed of fly ash and high-density polyethylene (HDPE). It is considered as an eco-friendly material because its use would contribute to reduce the amount of waste going to landfills. One of most promising applications of SLA is related with the geotechnical engineering field because of its low density that when combined with natural soils may produce a composite backfill material with adequate mechanical properties. This research focuses on testing SLA material properties, including material characterization, trial mixes of SLA with natural aggregates, and compaction tests to obtain the optimum dry density. The composite soil meets the AASHTO classification standards for A-2-4 soils. The validation of the observed behavior lead to propose at least three basic applications related with natural disasters prevention: a) efficient design of retaining walls with lower lateral pressures, b) control of settlements using low density composite soils over compressible soils, and c) slope stability problems.

Abstract

Slope stability analysis is a challenging task when complex stratigraphies, complex geometries and spatially variably soil parameters are considered. Numerical methods, such as the finite element method are commonly used in slope stability analyses, however, these methods require significant user input when meshing geometries consisting of heterogeneous and spatially variable materials. This paper presents a numerical technique combining the scaled boundary finite element method and image-based meshing for slope stability analysis. The inputs for the analyses require images detailing the stratigraphy and the spatial variation of the material properties. Quadtree decomposition is applied to simultaneously generate meshes and consider the spatial variation of material properties directly from the images through a mapping technique. The stability of slopes is analysed assuming an elastoplastic Mohr-Coulomb constitutive model for the soil. The shear strength reduction technique is applied to evaluate the shear reduction factor iteratively to define the factor of safety of the slope. Coal slopes at Yallourn open-pit mine, Victoria, Australia was considered, forming the basis of a case study to demonstrate the applicability of the presented method.