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The mechanics of granular materials at the macroscopic scale inherently depends on the particle interactions occurring at the microscopic scale. In recent decades, growing investigations have explored the mechanics of granular materials subjected to thermal cycles, as they involve complex responses that bear significance for science, engineering, and technology. However, the fundamental understanding of the mechanics of granular materials subjected to thermal cycles remains hindered by the absence of empirical evidence into the microscopic particle interactions that govern the macroscopic response of such materials. For the first time, this study presents direct experimental evidence obtained via synchrotron X-ray microtomography to reveal the behavior of the particles that constitute granular materials during thermal cycling. This work experimentally confirms the existing theory by which thermally induced particle interactions drive a macroscopic volumetric expansion and contraction of granular materials upon heating and cooling, respectively, and the development of irreversible volumetric deformations upon the completion of thermal cycles. The results uncover the evolution of particle non-uniform translations, rotations, and contact variations during thermal cycling, which all inherently depend on particle shape. [ABSTRACT FROM AUTHOR]

A novel position-dependent body force-based confinement for simulating triaxial tests using the Discrete Element Method is presented. The said method is used to perform triaxial simulations on mono-disperse and segregated assemblies of glass spheres. The macroscopic load response obtained in simulations is validated with the experimental load response. A mesh construction algorithm is presented to check whether the confinement applied in the triaxial simulations is accurate. The particle displacement data obtained from triaxial simulations are used to obtain a particle-wise average strain tensor. This is further used to compare the strain localisation between the mono-disperse and segregated assemblies. It is observed that, in the segregated assembly, the interface between the two particle phases acts as a barrier for strain localisation, and the smaller particles preferentially undergo a higher degree of shear strain on average. [ABSTRACT FROM AUTHOR]

To enhance our understanding of soil behavior at critical states, considering that natural soil is composed of granular matter, a quasi-static inertia number taking soil compaction into account is proposed. In analyzing classical triaxial test data of soil, the scaling law of quasi-statically deforming grains at the critical state is explored; a simple linear relationship is found between the coefficient of friction and the proposed number. This scaling law describes quantitatively the influence of initial compaction, shear rate, confining pressure, and particle size on the frictional strength of granular soils when they reach the critical state. The number proposed is employed to describe the scaling of volumetric behavior of granular soils undergoing quasi-static deformation. The difference between the particle volume fraction at the critical state and that at the initial compacted state is also found to be linearly correlated with the quasi-static inertia number, for soil at the critical state. [ABSTRACT FROM AUTHOR]

The effects of the stress loading rate and maximum servo wall speed on the instability characteristics of granular materials were investigated using stress-controlled biaxial compression simulation. The results indicate that: (1) the stress loading rate affects the destabilization process of the specimen, with a higher stress loading rate making it easier for the sample to destabilize in a shorter time. (2) The maximum servo wall speed impacts the shear behavior of the specimen and can even lead to simulation test failure. It is therefore strongly recommended that this parameter be listed as a key parameter in future studies. (3) Based on the above analysis, a new conceptual framework was proposed to characterise the different cases of stress-controlled tests, which can guide the rational selection of rates. [ABSTRACT FROM AUTHOR]

The different flow regimes in a two-dimensional silo with a vibrated base are studied in terms of the usual statistical techniques and information theory. The passage of granular material through the mouth of the silo is analyzed by real-time analysis of images captured by a standard video camera. The brightness of these images is measured and recorded at very small time intervals (100 frames per second). The experiment is repeated for different values of the vibration intensity. Data recognizer wlzip directly treats the resulting b(t) files (brightness time series) based on data compressor techniques, yielding the information content measured by the mutability μ function. μ has not previously been considered as part of the conventional treatment of flow in granular media. The results obtained here clearly demonstrate the usefulness of mutability as a tool for distinguishing between different flowing regimes directly from the brightness sequence, with no manipulation of the series. This shows that information theory techniques can provide a complementary description of the discharge of granular materials and its control through data compression algorithms. [ABSTRACT FROM AUTHOR]

Investigations into the various properties of granular matter composed of particles with defined shapes have gained increasing attention. Additive manufacturing, with its freedom of shape and rapid prototyping capabilities, has significantly contributed to these studies. However, this technique may introduce defects in the manufactured particles, which can significantly affect the properties of granular materials. The extent of these defects on particles of different shapes is investigated here. Particles of various shapes (cube, octahedron, quatropod, stellated octahedron, tetrahedron, and tetrapod) were manufactured and subsequently imaged using micro-Computed Tomography. The surface roughness, solidity, and convexity of the particles were quantified. Discrete element simulations of granular bed porosity, utilizing both idealized and real particle shapes, were conducted with different surface mesh resolutions and frictional parameters. A clear influence of the manufacturing process on the packing properties of 3D printed particles was identified. This influence is not uniform across all shapes and is directly correlated with the particle convexity. For numerical simulations, a shape-dependent correction of particle density and surface characteristics are imperative for each shape under consideration, despite the fact that the particles were manufactured using the same technique and material. [ABSTRACT FROM AUTHOR]

Understanding the ejecting behavior of granular materials under impact conditions is of vital important for the asteroid sampling and defense. During the impact and penetration stages, the interaction between the projectile and the target controls the impact-induced ejecta behavior. However, the correlation between projectile nose shape and the formation and expansion characteristics of the ejecta remains unclear. In this study, a vertical launch system and high-speed camera were used to carry out the experiments of projectile impact on sand target at 100 m/s. The variations of ejecta parameters induced by different projectile shapes (cone and ogive) and sharpness (cone angles of 30°, 60°, 120°; Caliber-Radius-Head values of 0.5, 1.0, 3.0) were compared. The results showed that both the formation and expansion of the ejecta are influenced by the projectile shape, especially the sharpness of projectile nose. Ejecta parameters such as the emergence time, horizontal expansion velocity, and ejecta mass are positively correlated with the sharpness of projectile nose, while emergence diameter and ejecta angle exhibit a negative correlation. The above observed phenomena are attributed to the energy deposition rate of the projectile on the target during the impact stage and the flow direction of sand grains after the projectile-grain interaction during the penetration stage. These findings can gain an insight into the influence of projectile shape on the ejecting behavior of granular materials. In addition, these findings offer valuable references for the modification of ejecta models that incorporate projectile nose shapes and contribute to the design of impact sampling mechanisms in practical tasks. • A vertical launch system is applied to test the ejecta formed under projectile impacts on dry sand targets. • The emergence time, diameter, angle, horizontal expansion velocity, and mass of ejecta are analyzed. • The correlation of ejecta parameters with projectile nose shapes and sharpness is examined. [ABSTRACT FROM AUTHOR]

Ground liquefaction potential analysis is a fundamental characterization in areas with continuous seismic activity, such as Ecuador. Geotechnical liquefaction studies are usually approached from dynamic penetration tests, which pose problems both in their correct execution and in their evaluation. Our research involves analyzing dynamic penetration tests and microtremor geophysical surveys (horizontal-to-vertical spectral ratio technique, HVSR) for analyzing the liquefaction potential at the base of the San Marcos dam, a reservoir located in Cayambe canton (Ecuador). Based on the investigations performed at the time of construction of the dam (drilling and geophysical refraction profiles) and the application of 20 microtremor observation stations via the HVSR technique, an analysis of the safety factor of liquefaction (SFliq) was conducted using the 2001 Youd and Idriss formulation and the values of the standard penetration test (SPT) applied in granular materials (sands). In addition, the vulnerability index (Kg) proposed by Nakamura in 1989 was analyzed through the HVSR records related to the ground shear strain (GSS). The results obtained in the HVSR analysis indicate the presence of a zone of about 100 m length in the central part of the foot of the dam, whose GSS values identified a condition of susceptibility to liquefaction. In the same area, the SPT essays analysis in the P-8A drill hole also shows a potential susceptibility to liquefaction in earthquake conditions greater than a moment magnitude (Mw) of 4.5. That seismic event could occur in the area, for example, with a new activity condition of the nearby Cayambe volcano or even from an earthquake from the vicinity of the fractured zone. [ABSTRACT FROM AUTHOR]

We study pore-scale rheological phenomena in two-dimensional sheared wet granular materials. Simulations use a coupled cascaded lattice Boltzmann and discrete element method, to model the liquid–gas multiphase flows and multiple-solid-particle dynamics, respectively. The wet granular material is prepared by first filling a rectangular domain with solid particles and then partially filling the pores between the particles with the liquid phase. The material is then sheared based on standard Couette flow configuration, i.e., with lid-driven velocities U and -U on the top and bottom walls, respectively. The simulations show that the apparent viscosity of the system attains a minimum when the material is wet but not fully saturated, i.e., at a saturation of ∼0.10. Such an observation is coherent both for materials composed of monodisperse and polydisperse particles. Interestingly, this observation coincides with the experimental finding of the decrease in sliding friction on sand by adding a small amount of water. The underlying mechanism is elucidated based on the pore-scale study of liquid patch dynamics. It is shown that, with increasing liquid saturation, the rheology of the wet granular materials is affected by two competing effects: (i) a larger number of liquid patches appear leading to fluidization of the system and (ii) larger patches are formed, clogging the flow. The minimum apparent viscosity saturation of ∼0.10 coincides with the maximum of the product of the two factors: the number of liquid patches and ratio between the system height and largest patch height. [ABSTRACT FROM AUTHOR]

The granular mechanics of lunar and Martian regolith remain inadequately understood, impeding progress in successful exploration, landing, drilling, sampling, and construction activities on extraterrestrial surfaces. This study aims to bridge this knowledge gap by investigating the granular behavior of the lunar and Martian regolith under impact conditions. Impact cratering experiments were conducted for the lunar highlands, lunar mare, Martian regolith simulants (LHS-1, LMS-1, and MGS-1, respectively), and terrestrial silica sand with similar particle sizes as target granular materials, with a sphere projectile dropping at low velocities. A systematic analysis was undertaken to elucidate the influence of parameters, including the fall height of the projectile, impact velocity, kinetic energy of the projectile, porosity, cohesion, and internal friction angle, on the resulting crater depths. Our findings demonstrate that the crater depths of regolith layers of the lunar highlands and Martian surfaces are greater than those of the lunar mare regolith and terrestrial silica sand layers. For example, the crater depth of the lunar highland regolith layer is about two times greater than that of the terrestrial silica sand layer at an impact velocity of 40–70 cm/s. Additionally, our power-law scaling highlights less resistance to crater impact in the lunar and Martian regolith layers than in the terrestrial sand layer. Our study highlights a significant difference in granular behavior between the Earth's sand layer and the lunar and Martian regolith layers, providing valuable insights for future exploration, coring, drilling, and resource utilization endeavors on the lunar and Martian surfaces. [ABSTRACT FROM AUTHOR]

The influence of silo width on dense granular flow in a two‐dimensional silo is investigated through experiments and simulations. Though the flow rate remains stable for larger silo widths, a slight reduction in silo width results in a significant increase in flow rate for smaller silo widths. Both Beverloo's and Janda's formula accurately capture the relationship between the flow rate and outlet size. Flow characteristics in the regions near the outlet exhibit local self‐similarity, supporting Beverloo and Janda's principles. Moreover, global self‐similarity is analyzed, indicated by the transition in flow state from mass flow in regions far from the outlet to funnel flow near the outlet. The earlier occurrence of this transition favors to enhance the grain velocity and consequently increases the dense flow rate. An exponential scaling law is proposed to describe the dependencies of flow rate, grain velocity, and transition height on silo width. [ABSTRACT FROM AUTHOR]

Recent advancements in railway construction have emphasized environmental sustainability, integrating considerations of environmental impact into the planning and execution of infrastructure projects to reduce costs and mitigate adverse effects. This study investigates the use of steel slag as a sustainable alternative for railway ballast, grounded in shakedown theory. The characterization of the aggregates was performed in accordance with NBR 5564 and AREMA standards, confirming that the material meets most requirements. The mechanical behavior of the ballast was analyzed under cyclic loading conditions, assessing permanent deformation and the material's ability to achieve stability (shakedown). Triaxial tests with repeated loading simulated real railway conditions, applying vertical stresses up to 600 kPa and confining pressures ranging from 35 to 200 kPa. The results indicate that steel slag aggregates exhibited promising performance, with seven specimens achieving stable deformation levels, characterized by residual deformations of less than 2.5 mm. Notably, these specimens approached deformations on the order of 10 − 7 , indicating stability under cyclic loading. Furthermore, a comparative analysis of shakedown criteria proposed by various authors revealed variations in limits for granular materials, enhancing the understanding of steel slag aggregate behavior. The experimental results were validated through numerical simulations conducted with Systrain software 2.0, which simulated a loading condition of 32.5 tons per axle, confirming the observations with maximum principal stresses ranging from 166 to 184 kPa in the ballast. The analysis showed that steel slag aggregates can withstand stress levels higher than those of granodiorite, reinforcing their viability as a sustainable alternative for railway ballast. [ABSTRACT FROM AUTHOR]

This paper presents a multiscale experimental study integrated with numerical simulations examining the mechanics of polydisperse granular mixtures composed of coarse‐grained particles mixed with varying percentages of fines. The study includes macroscale wave propagation tests using bender elements on isotopically compressed granular samples to investigate the stiffness variation with changes in size ratio (SR) and fines content (FC). Empirical equations were developed to predict stiffness based on the experimental data, using the concept of equivalent void ratio to represent the influence of void ratio on stiffness. A newly introduced parameter called size disparity indicator was used to consider the coupled effects of size disparity and fines content on stiffness. Microscale assessment of the individual contacting grains revealed that stiffness (at grain scale) is affected by changes in grain size, even when the SR is less than 6, however, the experimental observations of the shear modulus behavior from the macroscale test results reveal minimal effect of FC. Furthermore, numerical simulations using the discrete element method were conducted on the polydisperse granular mixtures to demonstrate the coupled effect of SR and FC on the structural matrix formation, thereby influencing the force transfer among contacts resulting in varying stiffness behavior. Our findings provide valuable insights into the behavior of polydisperse granular mixtures in engineering applications. [ABSTRACT FROM AUTHOR]

As a crucial component of batteries, the binder connects the granular active material and the conductive additive into a whole electrode and attaches to the surface of the current collector through a variety of interactions to maintain the electron/ion transport and the integrity of the electrode during the charge–discharge cycles. However, conventional binders are mostly synthetic polymers with single structures and properties and are not renewable, thus the development of multifunctional green renewable binders derived from biomass materials is attracting increasing attention. The distribution and function of lignocellulose in plants are similar to those of binders in electrodes. They strengthen the structure of the plants via hydrogen bonding, π–π conjugation, hydrophobicity, etc., and maintain the diffusion and transport of molecules, aligning with the criteria for the next generation of battery binders. In the context of the significant impact of binders on the performance of advanced battery systems, recent progress in research on lignocellulose derivative-based binders in various batteries is summarized. The research potential and challenges of lignocellulose and its derivatives as binder materials are discussed, with the hope of shedding light on the rational construction of robust and stable lignocellulose-based binders for high-energy-density batteries. [ABSTRACT FROM AUTHOR]

We propose a constitutive model for both the solid-like and fluid-like behavior of granular materials by decomposing the stress tensor into quasi-static and collisional components. A hypoplastic model is adopted for the solid-like behavior in the quasi-static regime, while the viscous and dilatant behavior in the fluid-like regime is represented by a modified μ (I) rheology model. This model effectively captures the transition between solid-like and fluid-like flows. Performance and validation of the proposed model are demonstrated through numerical simulations of element tests. [ABSTRACT FROM AUTHOR]

The anisotropic microstructure of granular materials has a profound effect on their macroscopic behaviour and can be characterised using a fabric tensor. To include of fabric in the critical state theory (CST), anisotropic critical state theory (ACST) was proposed by modifying the state parameter (ψ) of CST to a fabric-dependent dilatancy state parameter (ζ) . Noteworthy that ψ showed a very strong correlation with characteristic features (e.g. instability, phase transformation and characteristic state) of macroscopic behaviour and, as a result, it has been adopted in many constitutive models. While ζ aided the inclusion of fabric in ACST models, the correlation between ζ and characteristic features has not been evaluated in detail yet, although a large number of works are found on micromechanics and fabric only. In this study, a large number of discrete element method simulations for drained and undrained triaxial were conducted to evaluate the correlation between ζ and characteristic features. To this purpose, the correlation between stress ratio and both classic and dilatancy state parameter (ψ and ζ ) were studied in important characteristic features (e.g. instability, phase transformation and characteristic state). It was found that this correlation was improved using ζ which might be due to the inclusion of fabric in our model. This observation is new and significant for inclusion of fabric evolution in constitutive modelling. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) has emerged as an essential computational tool in geotechnical engineering for the simulation of granular materials, offering significant advantages over traditional continuum-based methods such as the finite element method (FEM) and the finite difference method (FDM). The DEM's ability to model particle-level interactions, including contact forces, rotations, and particle breakage, allows for a more precise understanding of granular media behavior under various loading conditions. However, accurate DEM simulations require meticulous calibration of input parameters, such as particle density, stiffness, and friction, to effectively replicate real-world behavior. This study proposes a simplified calibration procedure, intended to be conducted prior to any granular material flow DEM modeling, based on three fundamental physical tests: bulk density, surface friction, and angle of repose. The ability of these tests, conducted on dry quartz sand, to accurately determine DEM micromechanical parameters, was validated through numerical simulation of cylinder tests with varying height-to-radius ratios. The results demonstrated that this calibration approach effectively reduced computational complexity while maintaining high accuracy, with validation errors of 0% to 12%. This research underscores the efficacy of simplified DEM calibration methods in enhancing the predictive reliability of simulations, particularly for sand modeling in geotechnical applications. [ABSTRACT FROM AUTHOR]

The potential adverse health effects of antiperspirant use are of interest to patients, primary care providers, dermatologists, and pathologists. In rare instances, antiperspirants containing aluminum–zirconium complexes have been associated with granulomatous dermatoses despite being deemed non‐sensitizing in experiments. In this case study, we present a detailed examination of an axillary granuloma in a 28‐year‐old female who had been using an aluminum–zirconium‐based antiperspirant for several years and presented with a left axillary nodule that was excised and analyzed using scanning electron microscopy with energy‐dispersive x‐ray analysis (SEM/EDXA). Histopathological examination revealed a foreign body‐type reaction with amphophilic granular material within giant cells that corresponded to collocated zirconium and aluminum on SEM/EDXA elemental maps. Our case adds to the limited reports of axillary granulomas related to aluminum–zirconium complexes. It illustrates the histopathological appearance and in situ distribution of the aluminum–zirconium complexes, supporting the formation of foreign body‐type granulomas. Additionally, our case study illustrates the potential role of these compounds in such reactions and aims to increase awareness among pathologists and clinicians. [ABSTRACT FROM AUTHOR]

Ground reaction in terms of stress and displacement analysis is one of the major challenges in tunnel design and is helpful for understanding the stability around the excavation zone. In this paper, the analysis of stress, strain responses and radial displacement around circular tunnel excavated in cohesive-frictional granular materials is discussed via an innovative multi-scale approach (FEM × DEM) that combined finite element (FEM) and discrete element (DEM) methods and compared to other solutions obtained with conventional constitutive laws. Thanks to simulations, (i) the Ground response curve is then established and provides a better understanding of the complex behaviour in the vicinity of the tunnel; (ii) the prediction by FEM × DEM approach differs considerably from conventional constitutive laws; and (iii) in a unique manner, macroscopic and microscopic analyses are simultaneously performed showing that at the macroscopic level (FE mesh), diffuse failure mode are observed, while at the microscopic level (DEM level), microscopic evolutions are observed to be strictly related to the macroscopic behaviour. [ABSTRACT FROM AUTHOR]

An experimental study on the packing thickness (PT) dependent plasma emission caused by laser ablating thin-layer microgranular samples in air was conducted using three sets of size-selected copper grains (median size d50 = 53 mm, 72 mm, and 100 mm, respectively). For each size-selected case, the PT parameter was tuned from 0.15 to 1.00 mm through varying the amount of grains packed into a vessel with a steel bottom wall and the emission spectra of laser-induced plasma were measured at various PT. It is found that there is a striking threshold phenomenon in the measured behavior of PTdependent plasma emission. Specifically, when PT is less than a threshold PTth, the emission intensity exhibits an exponential decreasing with incremental thickness; however, when it exceeds PTth, the emission intensity becomes almost constant. It is also found that the PTth slightly depends on grain size but the ratio of PTth to d50 seems to be size independent. Combining the mechanical fundamentals of granular materials, we interpreted the findings by considering a PT-dependent effect of the vessel's bottom on the formation circumstance of a laser-induced plasma. This work has practical significance in assessing a threshold thickness above which laser-induced breakdown spectroscopy, as an analytical technique to quantify elements embedded in microgranular materials, is viable regardless of PT difference. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of soils subjected to any stress path in which deviatoric stresses are present is heavily characterised by non-linearity, irreversibility and is strongly dependent on the initial state of stress. The latter, for the majority of geotechnical applications, is normally determined by the at-rest earth pressure coefficient K0, even though this state is valid, strictly speaking, for axisymmetric conditions and for zero-lateral deformations only. Many expressions are available in the literature for the determination of this coefficient for cohesive and granular materials both for normal consolidated and over-consolidated conditions. These relations are available for low to medium stress levels. Results of an extensive experimental investigation on two sands of different mineralogy up to very high stress (120 MPa) are reported in the paper. For reach very high vertical stresses, a special oedometer has been realised. In the loading phase (normal consolidated sands), the coefficient K0n depends on the stress level. It passes from values of about 0.8 to values of about 0.45 in the range of effective vertical stress σ′v = 0.5–4 MPa. Subsequently, K0n is about constant and varies between 0.45 to 0.55 up to very high vertical effective stresses (120 MPa). For the sands employed in the tests, Jaki's relation did not lead to reliable results at relatively low pressures, while at high pressures, the same relationship seems to lead to reliable predictions if it refers to the constant volume angle of shear strength. For the over-consolidated sands, K0C strongly depends on the OCR, and for very high values of OCR, K0C could be greater than Rankine's passive coefficient of earth pressure, Kp. This result is due to the very locked structure of the sands caused by the grain crushing, with intergranular contact of sutured and sigmoidal, concavo-convex and inter-penetrating type, that confer to the sand a sort of apparent cohesion and make it similar to weak sandstone. [ABSTRACT FROM AUTHOR]

Earthquake‐triggered landslides are widely recognized. Despite extensive research on the seismic responses of landslides triggered by single earthquakes, there is a lack of understanding of the seismic responses of landslides due to earthquake sequences and multiple earthquakes, and the mechanisms of dynamic weakening under multiple earthquakes still lack support from experimental results. To explore their seismic response characteristics and triggering mechanism, a series of multi‐period vibrations ring shear tests and dynamic triaxial‐bender tests were conducted with glass spheres. The experimental results show that the co‐vibration slip occurred during the vibration process, and as the vibration periods increased, the sample gradually slipped after vibration, eventually leading to accelerated instability. The sample exhibited a transition from a solid‐semi‐solid state to a liquid state due to the increase in vibration periods. Further results show that the shear modulus progressively weakened with successive vibration periods. The weakening of the shear strength of the sample caused by multi‐periods vibration was affected by the amplitude, the vibration time, and the interval time between two periods of vibration. Our study provided insights into how multiple earthquakes of seismic sequence and seismically active area trigger landslides. Plain Language Summary: Earthquake‐triggered landslides are affected by seismic sequences and multiple earthquakes in the geological history, but how multiple earthquakes trigger landslides is still unclear. In view of the dynamic response characteristics and triggering mechanism of landslides triggered by multi‐stage earthquakes, we carried out dynamic ring shear experiments and dynamic triaxial‐bender experiments. The experimental results show that with an increase in the number of vibration period, the sample initially experienced no deformation after vibration, followed by decelerated deformation, and finally underwent accelerated unstable deformation, showing a phase transition process from solid‐semi solid to liquid. The experimental results further indicate that this was because the shear modulus of the sample decreased with the increase of the vibration period. Our results revealed how multiple earthquakes and seismic sequences trigger landslides. Key Points: Ring shear experiments show the deformation characteristics of granular materials under multi‐period vibrationsPost‐vibration slip controls the accelerated deformation and instability of granular materialsThe shear modulus of granular media decrease under multi‐period vibrations, resulting in phase transitions from solid‐semi solid to liquid [ABSTRACT FROM AUTHOR]

Surface morphology plays a crucial role in friction between two contacting geomaterial surfaces, yet many questions remain unanswered regarding how detailed frictional responses deviate from analytical solutions for smooth surfaces due to the presence of roughness. In this study, we revisit the Cattaneo‐Mindlin problem for contacts between two fractally rough elastic or elasto‐plastic spheres generated based on ultra‐high degree (e.g., up to 2,000) spherical harmonics with the corresponding wavelength less than a thousandth of the mean grain diameter. Transverse contacts are simulated by finite element method, validated by the extended Cattaneo‐Mindlin solution to full slide regime for smooth sphere contacts. Extensive simulations are conducted to study contacts between two rough spheres with various surface geometries, micro friction coefficients, normal contact distances, relative roughness, fractal dimensions, and wavelength ranges. Out results indicate that: (a) the new analytical solution can approximately predict the macro contact response except for extremely high relative roughness and narrow wavelength range; (b) deviations induced by roughness from smooth sphere contacts can be neutralized by plasticity, high normal contact interference, and high micro friction coefficient; and (c) fractal dimension impacts frictional contacts less than relative roughness. The main cause of these phenomena can be credited to the underlying microscale contact information. Contact area and stress distributions and their evolutions provide concrete evidence of these observed behavior. This work provides a pathway for applying computational contact mechanics to many geophysical fields, such as the asperity model in earthquake science and the mechanics of granular materials. Plain Language Summary: Geophysical bodies, such as faults, rocks, and grains, exhibit surface roughness across length scales. Contacts between rough surfaces are usually simplified to a rough‐to‐flat contact scenario. To release these strong assumptions, for the first time, extensive finite element simulations are conducted for transverse contacts between two rough grains. Particularly, grain roughness is controlled by ultra‐high degree spherical harmonics, which enables depicting surfaces of diverse grains from silica sands up to asteroids. Our results highlight the importance of surface features in frictional contacts, and indicate that the effects of roughness can be alleviated by the plasticity, contact conditions, and high intrinsic friction coefficient. Furthermore, fractality, quantifying how much the surface fluctuates over length scales, impacts frictional contacts less than roughness amplitude. This study provides a pathway for applying computational contact mechanics to many geophysical applications involving frictional contacts, such as asperity models in earthquake science and mechanics of granular materials. Key Points: Transverse contacts are simulated between two fractal rough grains generated by ultra‐high degree spherical harmonics for the first timeCattaneo‐Mindlin solution is extended to the full slide regime, capable of predicting the critical partial‐to‐complete sliding transitionEffects of roughness can be generally neutralized by plasticity, high contact interference, and friction coefficient [ABSTRACT FROM AUTHOR]

In this work, the frictional traction forces developing in the annular space between two concentric vertical cylinders consisting of the outer surface of a cylindrical rod and the inner sidewall of a wider circular cylinder will be analyzed. The experiments carried out for this study allowed us to measure the traction on the rod for several filling heights, H. For the rod, it is possible to find a linear relation between the theoretically computed traction T r o d and the traction measured experimentally, T r o d M . Based on these results, it is possible to understand the fascinating phenomenon of the lifting, by the rod, of the weights of the mass of grains and of the outer cylinder. Finally, a physical analogy between this problem and the upward movement of trees in tornadoes can be identified. [ABSTRACT FROM AUTHOR]

The article "Simulations in Bulk Solids Handling: Applications of DEM and Other Methods" from the Johnson Matthey Technology Review discusses the use of discrete element method (DEM) modelling in bulk powder handling processes. The book compiled by Professor Don McGlinchey focuses on simulation methods for granular solids transfer and transport operations within manufacturing environments. It provides insights into calibration, chute design, belt conveyor operation, pneumatic conveying, and erosion wear in powder handling processes. The article emphasizes the importance of understanding granular material properties and methods for efficient industrial powder processing. [Extracted from the article]

The nuclear density gauge (NDG) is the most established device for compaction control. Several studies have proposed alternatives to it, but none have been widely adopted for a variety of reasons. This paper presents the Sherbrooke Method (SM), which involves the use of innocuous, user-friendly, and low-cost devices. It uses frequency domain reflectometry (FDR) sensors to obtain bulk density and gravimetric water content. In this research, 442 field test comparisons between the SM and the NDG device, and 117 between the SM and physical tests were obtained at sites where a type of well-graded gravel (MG 20 in Quebec) was used. The FDR technology showed promising results, with good ability to predict bulk density and gravimetric water content. Moreover, the method presented low complexity of execution and the data emitted by the probe can be obtained in 1 minute. Nowadays, the total lapse of time from setting up the device to the final response (of 3 tests) is approximately 20 minutes. The SM also presents a bulk density precision comparable to that of other devices reported in the technical literature. [ABSTRACT FROM AUTHOR]

The mechanics and motion behavior of granular materials affect the production and life of human beings. In order to study the influence of the sliding friction coefficients corresponding to different contact types in the block discrete element method on the simulation results, this study established a block discrete element model to analyze a slope example based on the test method. The example was a homogeneous soil slope that did not consider water. The correctness of the models was verified by establishing the block discrete element slope model and comparing it with the known finite element method (FEM) model in terms of the maximum shear strain. Then, the sliding friction coefficient algorithm was embedded into the discrete element slope model for comparative analysis. The results show that in the calculations in the block discrete element method, the sliding friction coefficients of different contact types are different. Different sliding friction coefficients should be set based on different contact types to improve the accuracy of the simulation. Because the block discrete element model needs to preset the landslide surface of the slope, the displacement at the edge of the landslide surface is slightly different. The discrete element method (DEM) model was also compared with the block element model, and the results show that the DEM model is more stable. [ABSTRACT FROM AUTHOR]

High-modulus asphalt concrete (HMAC) has been widely used in the surface coating of high-grade pavement. Due to HMAC's modulus being significantly higher than traditional asphalt concrete, the mechanical responses of a pavement structure using an HMAC coating must be notably different from those of a traditional asphalt pavement structure. Moreover, when asphalt surface coating is fixed, the selection of base-course combinations will determine the mechanical response of the whole pavement structure. However, previous studies usually analyzed the mechanical response of pavement structures at limited combinations of base-courses, resulting in difficulties comprehensively understanding the laws of mechanics and effectively optimizing the HMAC pavement structure. Hence, in this study, a total of 108 groups of numerical experiments under six working conditions of base-course combinations are carried out using orthogonal experimental design to investigate the mechanical response of pavement structures using HMAC coatings using the PR MODULE high-modulus additive. The effects of pavement thickness, material modulus, and structural combination on mechanical responses are analyzed for the 108 groups to determine the optimal pavement combinations based on the balance of mechanical response and economic efficiency. The results show the following: The effect of the base layer type on mechanical response is more significant than that of the subbase layer type. Surface and undersurface layer thickness for the granular material base layer; surface and base layer thickness for the asphalt mixture base layer; and base layer thickness, subbase layer modulus, and base layer modulus for the inorganic binder mixture base layer are the key factors for mechanical response. Finally, six recommended HMAC pavement structure configurations for various base-courses are proposed. [ABSTRACT FROM AUTHOR]

The high‐speed impact‐resistanct materials are of great significance while their development is hindered by the intrinsic tradeoff between mechanical strength and energy dissipation capability. Herein, the new chemical system of molecular granular material (MGM) is developed for the design of impact‐resistant materials from the supramolecular complexation of sub‐nm molecular clusters (MCs) and hyper‐branched polyelectrolytes. Their hierarchical aggregation provides the origin of the decoupling of mechanical strengths and structural relaxation dynamics. The MCs' intrinsic fast dynamics afford excellent high‐speed impact‐resistance, up to 5600 s−1 impact in a typical split‐Hopkinson pressure bar test while only tiny boundary cracks can be observed even under 7200 s−1 impact. The high loadings of MCs and their hierarchical aggregates provide high‐density sacrificial bonding for the effective dissipation of the impact energy, enabling the protection of fragile devices from the direct impact of over 200 m s−1 bullet. Moreover, the MGMs can be conveniently processed into protective coatings or films with promising recyclability due to the supramolecular interaction feature. The research not only reveals the unique relaxation dynamics and mechanical properties of MGMs in comparison with polymers and colloids, but also develops new chemical systems for the fabrication of high‐speed impact‐resistant materials. [ABSTRACT FROM AUTHOR]

Three-dimensional printing of cementitious materials for construction has been extensively investigated in recent years, with several demonstration projects successfully carried out. These efforts aim to leverage the printing process to achieve more efficient production of components compared to conventional concrete technologies. This includes both the process itself (eliminating the formwork stage) and the flexibility in producing complexly shaped elements. To maximize the potential of 3D printing in the construction industry, additional steps must be taken, grounded in a holistic view of the entire process. This involves integration of the production chain, including design, materials, and manufacturing of components, to create elements with optimal performance, encompassing structural, environmental, and architectural aspects. Such multi-functionality requires the viewing of 3D printing not just as a production technology but as a platform enabling the integration of all these components. To advance this approach, quantitative tools are developed to optimize the following three key components: material composition; manufacturing parameters to ensure buildability; and design tools to optimize multiple performance criteria, particularly structural and architectural shape. A demonstration component, namely a post-tensioned beam, featuring two multi-functional characteristics—structural and architectural—is designed, produced, and evaluated. The scientific concepts and research tools used to develop these quantitative design tools are multidisciplinary, including rheological characterization, control of the internal structure and composition of granular materials, simulation of the mechanical behavior of green material during printing, and the hardened properties of the components, all utilizing structural optimization to enhance performance. [ABSTRACT FROM AUTHOR]

Rill swell (RS) events are outflows of dry, fine-grained material mainly observed at drawpoints in cave mining. These events can negatively affect production and have fatal consequences. Unfortunately, comprehensive studies analyzing these events are lacking. This paper uses the discrete element method to study RS events. With this method, a numerical model was constructed and calibrated based on an RS event recorded in Ridgeway Deeps Block Cave. Drawpoint geometries, material properties, and the initial mass of the fine material were then analyzed. The results show that both the brow beam height and drawpoint width had a noticeable influence on the RS magnitude, mainly on the tonnage of the flow and the distance reached by coarse particles dragged into the extraction drift. While the mass of fine material is crucial to the magnitude of RS events, results suggest that narrowing drawpoint width and/or increasing brow beam height can mitigate the impact of RS events. [ABSTRACT FROM AUTHOR]

We study the behaviour of a particle bed immersed in water when a flow generated by an oscillating plate is induced above it. We first consider a rigid plate submerged and oscillated over a particle bed. During upward motion of the plate, a portion of the bed fails, allowing particle displacement, and the bed surface to deform into a heap. We have already determined the flow of the fluid above and within the bed. This work describes the particle motion within the failed region of the bed: when the particles are mobile, they follow the fluid. We depth average the balance of mass and obtain an evolution equation for the displacement of the bed surface. We solve this equation and compare the predictions with the measurements of surface displacement in earlier experiments on rigid square plates. We carry out new experiments to measure the surface displacements under elongated plates. Elongated rigid plates behave similarly to the rigid square ones. Flexible plates produce multiple heaps. We determine that the peaks of these heaps are correlated with the flexural modes of the plates and occur at points along the bed at which the fluid pressure has its extreme values. Different plate flexural modes, resulting in different numbers of heaps, are produced by driving the plate at different frequencies. The particle motion within the bed and heap evolution under a flexible plate can be roughly described by regarding it as two or more rigid plates. We test the predictions of the theory against experiments. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of the effects of separation of spherical particles with different densities in a fast gravitational flow on a rough slope with varying flow parameters in order to increase the efficiency of the process. The determining role of the effect of quasi-diffusion separation in the process has been established, the intensive manifestation of which is facilitated by the formation of s-shaped profiles of the fraction of voids and velocity in the flow. The results of an experimental and analytical study of the efficiency of particle separation by density in a fast gravitational flow when shear deformations are activated by longitudinal pulses are presented. It has been established that when particles are exposed to the pulse effect from the open surface of the flow, its central part develops a zone with a typical s-shaped inflection in the velocity profile and void fraction, which functions like a quasi-diffusion separator that increases the efficiency of the process. [ABSTRACT FROM AUTHOR]

It is important to understand the flow behaviour inside wedge-shaped hoppers and accurately predict the discharge rate for the processing and handling of granular materials, regardless of whether the wedge hopper is symmetric or asymmetric. In this paper, the discrete element method (DEM) was used to reveal the flow behaviour of pellet feed in an asymmetric wedge-shaped hopper from the discharge rate, flow pattern, velocity distribution, normal contact force between particles and free-fall arch. The results showed that, with the hopper angle decreasing, the area of the active region of the particles increased, the stagnation zone decreased, and the free-fall arch became unstable. When the unilateral hopper angle was less than 45°, the discharge rate of the wedge-shaped hopper increased, and the average discharge rate reached the maximum value of 1.070 kg s−1 when the left and right hopper angles were equal to 15°. In addition, using the discharging mass proportion coefficient to represent the size of the region in which the unilateral hopper angle affected the flow of particles in the hopper, the hopper angle term in the Brown and Sellers model was corrected. The predictive errors of the corrected discharge rate model were less than 7.6% and 3.3% in the simulated and actual discharging tests respectively, which was better than that of the Brown and Sellers model. The results of the study could provide a theoretical basis for the intelligent upgrading of feed accurate handling equipment, and provide a reference basis for the design of asymmetric wedge-shaped hopper. • Simplified modeling of pellet feeds applied. • Discharge characteristics of an asymmetric wedge-shaped hopper revealed. • Discharge rate prediction model for an asymmetric wedge-shaped hopper developed. [ABSTRACT FROM AUTHOR]

The discrete-element method was employed to investigate the macro- and micromechanical behaviors of anisotropic granular specimens using orientational rotational shear (ORS) tests. The variations in the initial fabric orientation relative to the vertical direction were considered during the sample preparation stage. Several ORS tests were performed on samples with various initial fabrics, stress ratios, and densities. The contact-normal-based fabric tensor was considered as a measure of the internal structure of the granular assembly and employed in the detailed analysis. The proportional and noncoaxial components of the fabric tensor, with reference to the deviatoric stress tensor, exhibited similar sinusoidal evolution trends. The initial fabric represented by the bedding plane angle affected the phase angle of the cyclic variation waveforms of the proportional and noncoaxial components, whereas the stress ratio and initial density primarily affected their amplitude and magnitude. The decomposition of the strain increment tensor with respect to the stress indicated that the noncoaxial part was dominant, but the orthogonal component gradually vanished with an increase in the deviatoric strain, whereas the noncoaxial part decreased with an increase in the stress ratio. The new findings obtained in this study may provide useful guidance for the development of micromechanics-based constitutive models of granular materials subjected to ORS. [ABSTRACT FROM AUTHOR]

Hydrophobized soils have functional hydrophobic coatings to delay or restrict water infiltration and thus prevent infrastructure failure and long-term degradation. Over time, hydrophobized soils will be subjected to degradation under the action of external stresses, leading to the loss of its functional properties. Microencapsulation approaches, initially developed for self-healing applications emerge as a potential solution to enhance, switch (from hydrophilic) or prolong the longevity of hydrophobized soils. The aim of this study is to produce and investigate the effectiveness of microencapsulation to impart hydrophobicity in granular materials in response to external stimuli. In this research, polydimethylsiloxane (PDMS), with hydrophobic properties, is encapsulated in calcium alginate microcapsules with the ionic gelation method. The effectiveness of the microcapsules to induce hydrophobicity is investigated by mixing sand with microcapsules and quantifying the change of the contact angle and water drop penetration time (measures of hydrophobicity) under an external trigger, i.e., under drying and consecutive wetting–drying cycles. The results show that microcapsules release the hydrophobic cargo (PDMS) during shrinkage. After drying, the PDMS content in sand increased to 0.1–0.8% by mass of sand. The released hydrophobic cargo (PDMS) induced hydrophobicity in sands, reflected by a contact angle increase from 29.7° to at least 87.7°. The amount of polydimethylsiloxane encapsulated is a key parameter controlling the release of hydrophobic cargo. In addition, 4% capsule content in sands is identified as an effective microcapsule content in inducing hydrophobicity. [ABSTRACT FROM AUTHOR]

Flow-type landslides, including subaerial and submarine debris flows, have poor spatiotemporal predictability. Therefore, researchers rely heavily on experimental evidence in revealing complex flow mechanisms and evaluating theoretical models. To measure the velocity field of experimental flows, conventional image analysis tools for measuring soil deformation and hydraulics have been borrowed. However, these tools were not developed for capturing the kinematics of fast-moving soil–water mixtures over complex terrain under non-uniform lighting conditions. In this study, a new framework based on deep learning was used to automatically digitalize the kinematics of experimental flow-type landslides. Captured images were broken into sequences and binarized using a fully convolutional neural network (FCNN). The proposed framework was demonstrated to outperform classic image processing algorithms (e.g., particle image velocimetry, trainable Weka segmentation, and thresholding algorithms) over a wide range of experimental conditions. The FCNN model was even able to process images from consumer-grade cameras under complex shadow, light, and boundary conditions. This feature is most useful for field-scale experimentation. With fewer than 15 annotated training images, the FCNN digitalized experimental flows with an accuracy of 97% in semantic segmentation. [ABSTRACT FROM AUTHOR]

Particle shape irregularity is a notable feature of granular materials that exerts a profound influence on their mechanical behavior. This study examines the effects of particle overall regularity and surface roughness on the fabric evolution of granular materials using the Discrete Element Method (DEM). By connecting multiple spheres with varying sizes and positions, a diversity of clump particles characterized by distinct overall regularity (OR$OR$) and surface roughness (Rc$R_c$) are generated. A series of DEM simulations on drained triaxial compression tests have then been performed on granular assemblies with varying shapes, whereby their characteristics of contact intensity and the anisotropy of various fabric entities defined by contact normal, branch vector, and particle orientation, have been thoroughly investigated. The results show that increasing particle shape irregularity, indicated by smaller values of OR$OR$ and Rc$R_c$, is generally associated with an enhanced internal structure within the granular assembly, exhibiting a higher mechanical coordination number and a greater fabric anisotropy. Conversely, in granular assemblies with relatively high overall regularity, the fabric anisotropy is notably reduced, and this reduction cannot be compensated by enhancements in particle surface roughness. The evolution of two contact‐related fabric anisotropies is analyzed in relation to particle orientation‐based fabric anisotropy, which is more profoundly influenced by particle overall regularity, underscoring its significant role in fabric evolution of granular materials. [ABSTRACT FROM AUTHOR]

The applicability of particle-scale modeling using the discrete-element method (DEM) is typically evaluated by comparing simulation results with stress–strain responses observed in elementary tests. This validation at the global level may not guarantee that the simulation can capture realistic particle-level motion. Thus, this study investigated the applicability and limitation of two types of DEM models, through the comparison with experimental results of biaxial shearing tests on bidisperse granular assemblies comprising circular (round) and hexagonal (angular) particles under various confining pressures. Experimental data wherein particle rotations were identified by novel image analysis technique were used to evaluate whether the DEM models could accurately reproduce macroscopic stress–strain relationships and microscopic particle responses. Experimental findings suggested that particle rotations play a crucial role in granular deformation and are influenced by the particle shape. A detailed DEM model with precise particle shapes effectively replicated both macroscopic stress–strain relationships and microscopic responses, including particle rotation and interlocking at global and local levels. Conversely, a simpler ad hoc DEM model, which incorporates rolling resistance for circular particles, could imitate the stress–strain relationships of hexagonal particles but fell short in replicating microscopic responses accurately. [ABSTRACT FROM AUTHOR]

Accurate topographic data are essential for quantitative structural analysis, both in natural settings and in the laboratory. The selection of modeling materials (with appropriate rheological properties) is known to be fundamental for the success of scaled physical analog experiments. However, the optical properties of analog materials and their impact on the reliability and precision of high‐resolution topographic reconstructions have not (to our knowledge) previously been assessed. Here we evaluate the effects of material composition, color, and grain size on Structure‐from‐Motion (SfM) photogrammetry reconstruction efficacy for deformed and undeformed model configurations in the laboratory. Image collections for photogrammetry are acquired from multiple camera positions with a handheld digital camera, and reconstructions are registered using ground control points in a local coordinate system. Static experiments show that low reflectivity granular materials (e.g., silica sand, volcanic ash, pumice, and Al2O3) yield relatively reliable photogrammetry data for a wide range of grain sizes (44–2,400 μm) but larger grain sizes (≥250 μm) provide more robust results. Reflective materials (e.g., glass beads, wet clay) yield less reliable point‐clouds but the addition of low‐reflectivity granular materials (e.g., Al2O3 grains) on the surface of wet clay improves reconstruction results, with higher grain densities typically yielding lower point‐cloud residuals. SfM‐photogrammetry reconstruction of deformed clay analog models tends to improve at higher extension magnitudes because of fault and associated texture development on model surfaces. We anticipate that our results will help practitioners to improve the precision and reliability of photogrammetric data acquired in the analog modeling laboratory. Key Points: Low‐reflectivity granular materials yield more reliable Structure from Motion topographic reconstructions than wet clay or reflective granular mediaApplication of granular material to wet clay surfaces improves the reliability and precision of model surface reconstructionsFault development imparts surface texture to model surfaces, improving topographic reconstruction results [ABSTRACT FROM AUTHOR]

The baffle design resisting dry granular flow is still impeded by the effect of the particle size distribution coupled with the influence of Froude characteristics on baffle performance – for example, the deceleration process and run-up process. Based on discrete-element method simulation, this study investigated the baffle deceleration and granular flow run-up. Baffle deceleration is controlled by the change of particle contact behaviour behind the baffle slits and is more sensitive to the particle size than the Froude characteristics of granular flow. Although the granular flow run-up height is also affected by the debris–slit interaction, it is mainly dominated by the flow climbing along the baffle, which is more sensitive to the Froude characteristics and stress-transfer mechanism. Bidisperse granular flow has more complex interaction with the baffle compared with monodisperse flow. The effect of material inhomogeneity on baffle performance depends on the particle content. For baffle design, the first array can be considered as a reference. The estimation of the baffle deceleration potential and height with consideration to unsteady dynamics and material inhomogeneity is also presented in this paper. [ABSTRACT FROM AUTHOR]

Cyclic resistance curves, derived through undrained element tests, are central to the study of liquefaction. Their use implies that water drainage is negligible during an earthquake. Nevertheless, a growing body of evidence suggests that this hypothesis is not realistic. In proximity to the interface of a liquefiable layer with an overlying lower permeability layer, upwards water flow can lead to localised, co-seismic pore volume increase. The aim of this paper is to quantify the effects of pore volume increase on cyclic resistance curves. Cyclic triaxial experiments are presented, performed under undrained conditions and under conditions of volumetric expansion. A constant inflow rate is chosen for the sake of simplicity. Results show that even small inflow rates have a detrimental effect on cyclic resistance. A simplified methodology is developed, which can estimate cyclic resistance under constant water inflow rates, by assuming a superposition of isotropic unloading and undrained cyclic shearing. The results presented add to increasing evidence on how current liquefaction susceptibility assessments might not be conservative for layered deposits. In addition, they highlight significant aspects of soil response under partially drained conditions. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop new materials with adsorbent properties that can be used for the adsorption recovery of Au(III) from aqueous solutions. To achieve this result, it is necessary to obtain inexpensive adsorbent materials in a granular form. Concomitantly, these materials must have a high adsorption capacity and selectivity. Other desired properties of these materials include a higher physical resistance, insolubility in water, and materials that can be regenerated or reused. Among the methods applied for the separation, purification, and preconcentration of platinum-group metal ions, adsorption is recognised as one of the most promising methods because of its simplicity, high efficiency, and wide availability. The studies were carried out using three supports: cellulose (CE), chitosan (Chi), and diatomea earth (Diat). These supports were functionalised by impregnation with extractants, using the ultrasound method. The extractants are environmentally friendly and relatively cheap amino acids, which contain in their structure pendant groups with nitrogen and sulphur heteroatoms (aspartic acid—Asp, l-glutamic acid—Glu, valine—Val, DL-cysteine—Cys, or serine—Ser). After preliminary testing from 75 synthesised materials, CE-Cys was chosen for the further recovery of Au(III) ions from aqueous solutions. To highlight the morphology and the functionalisation of the material, we physicochemically characterised the obtained material. Therefore, the analysis of the specific surface and porosity showed that the CE-Cys material has a specific surface of 4.6 m2/g, with a porosity of about 3 nm. The FT-IR analysis showed the presence, at a wavelength of 3340 cm−1, of the specific NH bond vibration for cysteine. At the same time, pHpZc was determined to be 2.8. The kinetic, thermodynamic, and equilibrium studies showed that the pseudo-second-order kinetic model best describes the adsorption process of Au(III) ions on the CE-Cys material. A maximum adsorption capacity of 12.18 mg per gram of the adsorbent material was achieved. It was established that the CE-Cys material can be reused five times with a good recovery degree. [ABSTRACT FROM AUTHOR]

In slopes where high pore water pressure exists, deep counterfort drains (also called drainage trenches or trench drains) represent one of the most effective methods for improving stability or mitigating landslide risks. In the cases of deep or very deep slip surfaces, this method represents the only possible intervention. Trench drains can be realized by using panels or secant piles filled with coarse granular material or permeable concrete. If the trenches are adequately "socket" into the stable ground (for example sufficiently below the sliding surface of a landslide or below the critical slip surface of marginally stable slopes) and the filling material has sufficient shear strength and stiffness, like porous concrete, there is a further increase in shear strength due to the "shear keys" effect. The increase in shear strength is due both to the intrinsic resistance of the concrete on the sliding surface and the resistance at the concrete–soil interface (on the lateral surface of the trench). The latter can be very significant in relation to the thickness of the sliding mass, the "socket depth", and the spacing between the trenches. The increase in shear strength linked to the "shear keys effect" depends on the state of the porous concrete–soil interface. For silty–clayey base soils, it is very significant and is of the same order of magnitude as the increase in shear resistance linked to the permanent reduction on the slip surface in pore water pressure (draining effect). This paper presents the results of an experimental investigation on the shear strength at the porous interface of concrete and fine-grained soils and demonstrates the high significance and effectiveness of the "shear keys" effect. [ABSTRACT FROM AUTHOR]

Noise pollution has been considered as a serious threat to the health of humans. The application of sound absorption materials is an effective noise reduction approach. Fibrous materials exhibit the unique micro-structures including small diameter, large specific surface area, and high porosity, which has been widely developed for sound absorption. Recently, rapid growth has been observed in the coating treatment of fibrous based materials and composites for acoustic applications, which can be attributed to the advantages of a facile production process, cost-effectiveness, and good sound absorption capability. This review aims to provide a brief overview on different coating layers of fibrous materials for improved sound absorption properties. The details of various factors affecting the acoustic behavior of coating materials are described. Among them, polymer coating is a widely used acoustic treatment method, adding particles and nanofiber materials to the polymer matrix, and carrying out structural design, which can further improve the sound absorption performance of textile materials. According to the different needs of the application field, different coating treatment methods have their own advantages. In summary, coating materials are promising to be used in buildings and interiors for efficient noise reduction and control. [ABSTRACT FROM AUTHOR]

This paper develops an approximate stress distribution in a conical heap of jammed dry granular material loaded by gravity. An Eulerian formulation of elastic-inelastic response is used to explain why the residual stresses in the heap can be approximated by the current state of stress in the material. The proposed normalized stress components are functions of the normalized radial and vertical coordinates and are parameterized by only the angle of repose. It is shown that the vertical stress distribution applied to the base of the heap compares well with experiments using a rain procedure for sand deposition. [ABSTRACT FROM AUTHOR]

Microbially or enzyme induced carbonate precipitation has emerged to be a new type of soil improvement method. However, it appears that the biocementation process is affected by many factors and a common understanding on the control factors on the biocement effect has not been reached. This paper attempts to identify the main factors that controlling the MICP or EICP effect through an in-depth discussion on the fundamentals of biocementation process. Similar to other cemented granular materials, biocemented soil is a structural soil composite consisting of soil skeleton and biocement force chain or biocement network. The strength and stiffness of the biocemented soil is controlled by the reinforcement effect of the biocement network on the soil skeleton or the interplay of the soil skeleton and precipitates. The contribution of the strength by soil skeleton is affected by the soil types and soil properties, while the contribution of the precipitates is through the distribution of the biocement network and the properties of the precipitates. [ABSTRACT FROM AUTHOR]

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Large amplitude and unexpected waves are a regular source of natural disasters. Among them, impulse waves generated by landslides can represent a significant threat. Therefore, predicting and measuring the generation of such waves is essential. In this study, the phenomenon is modeled by a 2D‐experimental setup using a steady non‐uniform granular flow along a slope as a forcing wave generator. The present device provides a continuous supply of grains to avoid finite volume effects, as the part of the landslide actually involved in the wave generation strongly depends on the configuration and is not necessarily available in geophysical events. This system consists of an energy transfer between the granular flow and the wave generation which is characterized by a Froude number. It is found that the latter cannot be defined only based on the dry flow properties to characterize the wave. In particular, the dynamics underwater influence wave generation during a finite time. Accordingly, the present study shows that the wave maximum amplitude is governed by a newly defined Froude number, based on both dry and underwater granular flow properties. Moreover, it is shown that the granular deposit, specifically its runout, can be thought as a proxy of the immersed granular dynamics as long as the impact properties are still considered. Plain Language Summary: Landslides can cause huge waves if they impact the surface of an ocean, a lake or a sea. The properties of the landslide as well as the wave formation are complex features. In this study, an attempt to model this phenomenon experimentally at the laboratory scale is made, using a controlled granular flow impacting water in a 2D wave channel. The rapid evolution of this system requires a camera in order to extract the dynamics of both the wave and the granular material, simultaneously. From these measurements, it is shown that the wave and the granular flow are strongly linked at early stages. Moreover, after the maximum wave amplitude is reached, the wave propagates freely and may influence the granular deposit. This study proposes to link these processes and the wave characteristics to a single dimensionless parameter, which is a combination of Froude numbers. Key Points: A detailed analysis of new impulse wave experiments using a continuous granular supply is presented to highlight the wave‐granular couplingThe wave maximum amplitude is shown to evolve non‐monotonically with the deposit runoutConsidering wave‐granular interaction, a newly defined Froude number allows to accurately predict the wave characteristics [ABSTRACT FROM AUTHOR]