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The results of the experimental studies of the dynamics of the elastic working body of a vibratory conveying device equipped with two inertial vibration exciters are presented. The nature of the change in the mismatch of vibration source rotary frequencies and the degree of their mutual influence with an increase in the linear weight of bulk material has been established. The basic relationships of the structural and dynamic parameters of the vibrating device have been determined, which make it possible to increase the movement range of loose geomaterials.

The paper presents the results of studying separation processes of various mineral particles of different density in a hydrodynamic (water) environment in three laboratory models of counter-current drum separators with cylindrical, conical and multifaceted drums. Research results have shown that compared to cylindrical and conical drum separators, the multifaceted separator is most effective in separating and refining in a hydrodynamic environment. The high recovery of heavy minerals in the concentrate proves this fact.

Natural resource reservoirs usually consist of heterogeneous aggregated geomaterials containing a large number of randomly distributed particles with irregular geometry. As a result, the accurate characterization of the stress field, which essentially governs the mechanical behaviour of such geomaterials, through analytical and experimental methods, is considerably difficult. Physical visualization of the stress field is a promising method to quantitatively characterize and reveal the evolution and distribution of stress in aggregated geomaterials subjected to excavation loads. This paper presents a novel integration of X-ray computed tomography (CT) imaging, three-dimensional (3D) printing, and photoelastic testing for the transparentization and visualization of the aggregated structure and stress field of heterogeneous geomaterials. In this study, a glutenite rock sample was analysed by CT to acquire the 3D aggregate structure, following which 3D printing was adopted to produce transparent models with the same aggregate structure as that of the glutenite sample. Uniaxial compression tests incorporated with photoelastic techniques were performed on the transparent models to acquire and visualize the stress distribution of the aggregated models at various loading stages. The effect of randomly distributed aggregates on the stress field characteristics of the models, occurrence of plastic zones, and fracture initiation was analysed. The stress field characteristics of the aggregated models were analysed using the finite element method (FEM). The failure process was simulated using the distinct element method (DEM). Both FEM and DEM results were compared with the experimental observations. The results showed that the proposed method can very well visualize the stress field of aggregated solids during uniaxial loading. The results of the visualization tests were in good agreement with those of the numerical simulations.

Soil stabilization technology based on microbial-induced carbonate precipitation (MICP) has gained widespread interest in geotechnical engineering. MICP has been found to be able to improve soil strength, stiffness, liquefaction resistance, erosion resistance, while maintaining a good permeability simultaneously. MICP processes involves a series of biochemical reactions that are affected by many factors, both intrinsically and externally. This paper reviews various influential factors for MICP process, including bacterial species, concentration of bacteria, temperature, pH, composition and concentration of cementation solution, grouting strategies, and soil properties. Through this comprehensive review, we find that: (1) the species and strains of bacteria, concentration of bacteria solution, temperature, pH value, and the cementation solution properties all affect the characteristics of formed calcium carbonate, such as crystal type, appearance and size, which consequently affect the cementation degree and distribution in geomaterials; (2) the condition with temperature between 20 and 40 °C, pH between 7 and 9.5, the concentration of the cementation solution within 1 mol/L, and high bacteria concentration is optimal for applying MICP in soil. Under the optimal condition, relatively low temperature, high pH value, and low concentration of cementation solution could help retain permeability and vice versa; (3) the effective grain size ranging from 10 to 1000 µm. MICP treatment works most effectively for larger size, well-graded sand; (4) the multi-phase, multi-concentration or electroosmotic grouting method can improve the MICP treatment efficiency. The grouting velocity below 0.042 mol/L/h is beneficial for improving the utilization ratio of cementation solution. The recommended grouting pressure is generally between 0.1 and 0.3 bar for MICP applications in sand and should not exceed 1.1 bar for silty and clayey soils.

The precise determination of subsurface thermal properties is critical for ground-source heating systems. The geomaterials are inherently heterogeneous, and their thermal conductivity measured in laboratory and field tests often exhibits anisotropic behaviours. However, the accurate measurement of thermal responses in geomaterials presents a challenging task due to the anisotropy’s variation with the observed scale. Hence, a numerical method is developed in this work and illustrated by taking a typical anisotropic structure of geomaterials with the porosity of 0.5 as an example. The differences in data from laboratory measurements and field tests are discussed to explore the scale effect on anisotropic thermal properties. A series of simulation tests are conducted on specimens with varying dimensions using the finite element method. Results indicate that the thermal properties show a substantial sensitivity to the observation scale, the variation of which decreases with the sample dimensions. By comparing in situ data and laboratory results, the values of average thermal conductivity and corresponding anisotropy ratio are lower than those at small scales, indicating that careful consideration should be given to the thermal properties to account for heterogeneity and anisotropy. In addition, four upscaling schemes based on the averaging method are discussed. This study sheds light on the gap between the laboratory results and the field’s inherent properties and provides guidelines for upscaling small-scale results to field-scale applications.

Continuum numerical modeling of dynamic crack propagation has been a great challenge over the past decade. This is particularly the case for anticracks in porous materials, as reported in sedimentary rocks, deep earthquakes, landslides, and snow avalanches, as material inter-penetration further complicates the problem. Here, on the basis of a new elastoplasticity model for porous cohesive materials and a large strain hybrid Eulerian–Lagrangian numerical method, we accurately reproduced the onset and propagation dynamics of anticracks observed in snow fracture experiments. The key ingredient consists of a modified strain-softening plastic flow rule that captures the complexity of porous materials under mixed-mode loading accounting for the interplay between cohesion loss and volumetric collapse. Our unified model represents a significant step forward as it simulates solid-fluid phase transitions in geomaterials which is of paramount importance to mitigate and forecast gravitational hazards. Anticrack propagation in snow results from the mixed-mode failure and collapse of a buried weak layer and can lead to slab avalanches. Here, authors reproduce the complex dynamics of anticrack propagation observed in field experiments using a Material Point Method with large strain elastoplasticity.

In an age of depleting earth due to global warming impacting badly on the ozone layer of the earth system, the need to employ technologies to substitute those engineering practices which result in emissions contributing to the death of our earth has arisen. One of those technologies is one that can sufficiently replace overdependence on laboratory activities where oxides of carbon and other toxins are released. Also, it is one technology that brings precision to other engineering activities especially earthwork design and construction thereby reducing to lower ebb the release of carbon oxides due to inexact utilization of materials during geotechnical practices. In this review, the use of artificial intelligence techniques in geotechnics has been explored as a precise technique through which geotechnical engineering works don't impact on our planet due to precision. The intelligent learning algorithms of ANN, Fuzzy Logic, GEP, ANFIS, ANOVA and other nature-inspired algorithms have been reviewed as they are applied in the prediction of geotechnical and geoenvironmental problems and system. It is a complex exercise to conduct experimental protocols during the design and construction of earthwork infrastructures. Most times, such experimental exercises don't meet the required condition for sustainable design and construction. At other times, certain errors as a result of experimental set up or human misjudgment may mar the accuracy of measurements and release unexpected emissions. The employment of the evolutionary learning methods has solved most of the lapses encountered in repeated laboratory measurements. So, in this review work, the relevant computational intelligent techniques employed at different times, under different laboratory protocols and utilizing different materials, have been presented as a comprehensive guide to future researchers in this innovative and evolving field of artificial intelligence. With this extensive review, a researcher would not have to look far to get a technical and state of the art guide in the utilization of various intelligent techniques that would enable engineering models in a more efficient, precise and more sustainable approach to forestall multiple practices that release carbon emissions into the environment.

The microbial‑induced carbonate precipitation (MICP), as an emerging biomineralization technology mediated by specific bacteria, has been a popular research focus for scientists and engineers through the previous two decades as an interdisciplinary approach. It provides cutting-edge solutions for various engineering problems emerging in the context of frequent and intense human activities. This paper is aimed at reviewing the fundaments and engineering applications of the MICP technology through existing studies, covering realistic need in geotechnical engineering, construction materials, hydraulic engineering, geological engineering, and environmental engineering. It adds a new perspective on the feasibility and difficulty for field practice. Analysis and discussion within different parts are generally carried out based on specific considerations in each field. MICP may bring comprehensive improvement of static and dynamic characteristics of geomaterials, thus enhancing their bearing capacity and resisting liquefication. It helps produce eco-friendly and durable building materials. MICP is a promising and cost-efficient technology in preserving water resources and subsurface fluid leakage. Piping, internal erosion and surface erosion could also be addressed by this technology. MICP has been proved suitable for stabilizing soils and shows promise in dealing with problematic soils like bentonite and expansive soils. It is also envisaged that this technology may be used to mitigate against impacts of geological hazards such as liquefaction associated with earthquakes. Moreover, global environment issues including fugitive dust, contaminated soil and climate change problems are assumed to be palliated or even removed via the positive effects of this technology. Bioaugmentation, biostimulation, and enzymatic approach are three feasible paths for MICP. Decision makers should choose a compatible, efficient and economical way among them and develop an on-site solution based on engineering conditions. To further decrease the cost and energy consumption of the MICP technology, it is reasonable to make full use of industrial by-products or wastes and non-sterilized media. The prospective direction of this technology is to make construction more intelligent without human intervention, such as autogenous healing. To reach this destination, MICP could be coupled with other techniques like encapsulation and ductile fibers. MICP is undoubtfully a mainstream engineering technology for the future, while ecological balance, environmental impact and industrial applicability should still be cautiously treated in its real practice.

Searching for alternative material options to reduce the extraction of natural resources is essential for promoting a more sustainable world. This is especially relevant in construction and infrastructure projects, where significant volumes of materials are used. This paper aims to introduce three alternative materials, crushed ground glass (GG), recycled gypsum (GY) and crushed lime waste (CLW), byproducts of construction industry geomaterials, to enhance the mechanical properties of clay soil in Cartagena de Indias, Colombia. These materials show promise as cementitious and frictional agents, combined with soil and cement. Rigorous testing, including tests on unconfined compressive strength (qu) and initial stiffness (Go) and with a scanning electron microscope (SEM), reveals a correlation between strength, stiffness and the novel porosity/binder index (η/Civ) and provides mixed design equations for the novel geomaterials. Micro-level analyses show the formation of hydrated calcium silicates and complex interactions among the waste materials, cement and clay. These new geomaterials offer an eco-friendly alternative to traditional cementation, contributing to geotechnical solutions in vulnerable tropical regions.

This study explores using natural rubber latex (NRL) as a sustainable polymeric additive to improve the mechanical performance of cement-stabilized soil–crushed limestone waste (CLW) mixtures for pavement base applications. The experimental program involved varying cement contents (3%, 6%, and 9% by weight of soil) and NRL replacement levels (10%, 15%, 20%, and 25% of an 18% optimum water content, as determined by the standard Proctor test) under two target dry unit weights (16.6 and 17.6 kN/m3) and curing periods of 7 and 28 days. Unconfined compressive strength (UCS) tests and stiffness (Go) measurements were performed, while microstructural developments were examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results indicate that an optimal NRL replacement exists for each cement content, enhancing interparticle bonding through the formation of polymeric films that reduce porosity and improve the ductility of the matrix. However, excessive NRL was found to retard cement hydration and ultimately decrease strength. On average, a 28-day curing period produced a 38% increase in UCS over 7-day values, independent of the NRL dosage. Comparisons with literature standards, including the ASTM D4609 threshold of 345 kPa for field strength, confirm that the optimized mixtures meet and exceed the minimum performance requirements. These findings underscore the potential of NRL as a viable alternative to conventional synthetic latexes in sustainable pavement base materials.