This study evaluates dykes stability of bauxite residue storage facility using limit equilibrium (LEM) and finite element methods (FEM), considering diverse construction phases. In LEM, steady state seepage is simulated using piezometric line while factor of safety (FOS) is determined by Morgenstern-Price method using SLOPE/W. In FEM, actual loading rates and time dependent seepage is modelled by coupled stress-pore water pressure analysis in SIGMA/W and dyke stability is assessed by stress analysis in SLOPE/W, referencing SIGMA/W analysis as a baseline model. Both the analysis incorporated suction and volumetric water content functions to determine FOS. FEM predicted pore pressures are validated against in-situ piezometer data. The results highlight that coupled hydro-mechanical analysis offers accurate stability assessment by integrating stress-strain behaviour, pore pressure changes, seepage paths, and dyke displacements with time. It is found that inclusion of unsaturated parameters in Mohr-Coulomb model improved the reliability in FOS predictions.

With the Bulk Jupiter accident, the dynamic separation behavior of solid bulk cargoes in sea transportation, which is different from the usual liquefaction of cargoes, has gradually come to people's attention and is an almost empty field that urgently needs to be researched. In this work, we first conducted vibration table tests for bauxite, replaced bauxite with transparent soil with the same particle size distribution and moisture content, and combined image processing and analysis techniques to complete the detailed visualization of the dynamic separation process. Through the above research, this article reveals the essential characteristics of dynamic separation, including the changing rules of layer-wise water content, pore water pressure, particle motion, and pore water migration. It is concluded that the most apparent feature of the dynamic separation process is the generation of a free liquid surface containing fine particles in the upper layer. The article concludes with a systematic study of the dynamic separation of typical mineral soil. The novel experimental system developed in this study contributes to elucidating the mechanism of dynamic separation of minerals and soil from a precise perspective. [GRAPHICS] .

Differences in the fabric of reconstituted triaxial samples may increase the difficulty of achieving a unique critical state for some soils. Moreover, changes in the salt concentration of bauxite residue can result in non-unique critical state lines (CSLs). To evaluate the effects of fabric and pore-water chemistry on the critical state of bauxite residue, this paper compares the triaxial compression behavior of intact, slurry consolidated, and various forms of moist tamped samples, at a range of salt concentrations. The variations in fabric were also investigated using scanning electron microscopy and nuclear magnetic resonance (NMR) tests. The changes in pore-water chemistry were analyzed using X-ray methods and changes in salt concentration. The results showed that the particle agglomeration induced during reconstitution resulted in a more significant shift of the CSL than the decrease in salt concentration. Microimaging and shear behavior of samples showed that the slurry consolidation method may be the most suitable method for representing in situ behavior of clayey bauxite residue. NMR findings suggest that variations in water retained in the micropores of reconstituted samples stem from differences in microstructure. The implications of changes in salt concentration and sample microstructure on the design of clayey bauxite tailings storage facilities are discussed.

This study aimed to evaluate the potential of replacing fly ash (FA) with bauxite tailing (BT) slurry for geopolymer synthesis and investigate the long-term leaching behaviour of BT slurry/FA geopolymers (BFGs) for heavy metal immobilisation. The mechanical properties and heavy metal immobilisation efficiency of BFGs were tested, and numerical simulations were conducted to assess their environmental impact as a backfill material. The results showed that the incorporation of 5 Wt.% BT increased the early compressive strength of the geopolymer without any additional treatment. A small quantity of Cu2+ improved the mechanical strength, while excess heavy metals harmed the geopolymer. Heavy metal immobilisation efficiency decreased with increased heavy metal addition and exceeded 99.9% for Pb2+ and Cu2+ when simulating acid rain leachate. The modified Elovich equation described the leaching kinetics of Cu2+ well, and the leaching rate decreased with time. Numerical analysis indicated that Cu2+ leaching from landfill leachate occurred in three phases, with an initial increase followed by a gradual decrease, stabilisation, and diffusion into the surrounding soil layer. This study provides insight into the material's long-term stability and environmental performance, offering a scientific basis for relevant engineering applications.

Despite its vital importance to the contemporary economy, some drawbacks are mainly associated with waste derived from mining activity. This waste consists of tailings that are hydraulically disposed of in large impoundments, the tailings dams. As the dams are enlarged to accommodate higher amounts of materials, the stress states at which the deposited tailings are submitted change. This may be a concern for the stability of such structures once the geotechnical behavior of this material may be complex and challenging to predict, considering the existing approaches. Thus, the present study concerns the mechanical response of bauxite tailings under a wide span of stresses, ranging from 25 kPa to 4000 kPa. One-dimensional compression tests and isotropically drained and undrained triaxial tests were carried out on intact and remolded samples of the bauxite tailings. The after-shearing grain size distribution was characterized via sedimentation analysis. The results have shown a stress-dependency of the critical state friction angle for the intact material, which may be related to fabric alterations derived from structure deterioration and particle breakage. Overall, this research provides valuable insights into the response of structured and de-structured bauxite tailings, which are helpful for future constitutive modeling of such material.

How can we remain attentive to the scale of the environmental damage caused in traditional Maroon territories by the effects of the Plantationocene and the material vestiges of colonial and racial violence left by capitalism? Dwelling on conversations held with Maroon Cottica Ndyuka women living in Moengo, a small town established on the Cottica River in Eastern Suriname to support a bauxite industrial plant in the early twentieth century, this text seeks to illuminate what Maria Puig de la Bellacasa (2021) calls elemental affinities, relationships in which humans and more-than-humans interact in composing body and earth through refractive and diffractive effects. The paper observes how the women mixed and modeled clay, turning it into sculpted balls known as pemba or pemba doti, frequently used as a therapeutical and spiritual substance, and as food. In so doing, the text deals with processes such as creating, composing, undoing, decomposing, and perishing once the earth-as soil-takes part in and renders possible the existence of diverse creatures. This is a contribution toward an ethnography of (de)compositions of the earth that sets out from the affinities between earth and bodies, attentive to certain metamorphic possibilities, the multiplicities of relations in which soils act.