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This work examines the natural convection flow of an incompressible, viscous, and electrically conducting fluid down a vertical flat plate in the presence of conduction, as well as the effects of suction, magnetic field, viscous dissipation, porous medium, and heat generation. The governing momentum and energy equations have numerical solutions. The impacts of suction, heat production, magnetic, porosity, and viscous dissipation parameters on two-dimensional flow are discussed. Graphical representations of the velocity profile, temperature distribution, skin friction, rate of heat transfer, and surface temperature distribution are shown. The presence of porous media and improving suction values improves the friction drag but diminishes the energy transfer. The thermal production parameter raises the energy inside the flow but diminishes the heat transfer coefficient. This work attempts to offer important insights into these intricate processes by examining the effects of controlling factors including magnetic fields, porous medium, and suction parameters. This research conclusion may find applications in coolers, heat exchangers, and environmental remediation technologies that are more effective, advancing engineering and sustainable practices. [ABSTRACT FROM AUTHOR]

Two-dimensional magnetic materials have been increasingly studied and discussed in the field of spintronics due to their unique electronic properties, high spin polarizability, and a variety of magnetic properties. In this paper, we report a new two-dimensional bilayer hexagonal monolayer material bilayer hexagonal structure (BHS)-CrN2 by first-principles calculations. The BHS-CrN2 nanosheet is an intrinsic ferromagnetic semiconductor material, and the Curie temperature obtained by Monte Carlo simulation is 343 K. The absence of a significant imaginary frequency in the phonon spectrum indicates the dynamic stability of BHS-CrN2. After ab initio molecular dynamics simulation, the supercell of BHS-CrN2 remains a complete structure, indicating its thermal stability. The calculated elastic moduli satisfy the Born–Huang criterion, indicating that the BHS-CrN2 system has good mechanical stability. Interestingly, the compressive strain and O atom doping can transform the electronic structure of BHS-CrN2 from a semiconductor to a half-metal, and the Curie temperature of BHS-CrN2 can be further increased to 1059 K when a 5% tensile strain is applied. Furthermore, the BHS-CrN2 in the ferromagnetic state shows a significant in-plane magnetic anisotropy energy of 0.01 meV per Cr, and the CrP2 and CrAs2 show a large out-of-plane magnetic anisotropy energy of 0.207 and 0.988 meV per Cr, respectively. The results show that the intrinsic ferromagnetic semiconductor BHS-CrN2 has good stability, high Curie temperature, and tunable magnetic properties, which is a promising material for room-temperature spintronic devices. [ABSTRACT FROM AUTHOR]

We investigate the "roughness" of the energy landscape of a system that diffuses in a heterogeneous medium with a random position-dependent friction coefficient α(x). This random friction acting on the system stems from spatial inhomogeneity in the surrounding medium and is modeled using the generalized Caldira–Leggett model. For a weakly disordered medium exhibiting a Gaussian random diffusivity D(x) = kBT/α(x) characterized by its average value ⟨D(x)⟩ and a pair-correlation function ⟨D(x1)D(x2)⟩, we find that the renormalized intrinsic diffusion coefficient is lower than the average one due to the fluctuations in diffusivity. The induced weak internal friction leads to increased roughness in the energy landscape. When applying this idea to diffusive motion in liquid water, the dissociation energy for a hydrogen bond gradually approaches experimental findings as fluctuation parameters increase. Conversely, for a strongly disordered medium (i.e., ultrafast-folding proteins), the energy landscape ranges from a few to a few kcal/mol, depending on the strength of the disorder. By fitting protein folding dynamics to the escape process from a metastable potential, the decreased escape rate conceptualizes the role of strong internal friction. Studying the energy landscape in complex systems is helpful because it has implications for the dynamics of biological, soft, and active matter systems. [ABSTRACT FROM AUTHOR]

Recent experiments by Brückner et al. [Science 380, 1357 (2023)] have observed an anomalous chain length dependence of the time of near approach of widely separated pairs of genomic elements on transcriptionally active chromosomal DNA. In this paper, I suggest that the anomaly may have its roots in internal friction between neighboring segments on the DNA backbone. The basis for this proposal is a model of chain dynamics formulated in terms of a continuum scaled Brownian walk (sBw) of polymerization index N. The sBw is an extension of the simple Brownian walk model widely used in path integral calculations of polymer properties, differing from it in containing an additional parameter H (the Hurst index) that can be tuned to produce varying degrees of correlation between adjacent monomers. A calculation using the sBw of the mean time τc for chain closure predicts—under the Wilemski–Fixman approximation for diffusion-controlled reactions—that at early times, τc varies as the 2/3 power of N, in close agreement with the findings of the Brückner et al. study. Other scaling relations of that study, including those related to the probability of loop formation and the mean square displacements of terminal monomers, are also satisfactorily accounted for by the model. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferrovalley semiconductor materials with intrinsic spontaneous valley polarization offer new prospects for valley electronics applications. However, there are only a limited number of known promising candidate materials, which are in urgent need of expansion. In particular, the room-temperature 2D ferrovalley materials are still lacking. In this study, we predicted novel 2D ferromagnetic CeX 2 (X=Fe,Cl,Br) monolayers by using first-principles calculations. The monolayer CeX 2 is a bipolar magnetic semiconductor with robust dynamical and thermal stabilities, and easy magnetization direction is in the plane. Due to the simultaneous breaking of both inversion symmetry and time-reversal symmetry, the monolayer CeX 2 is exhibiting a spontaneous intrinsic valley polarization when magnetized along the out-of-plane z direction. Interestingly, monolayer CeBr 2 is a spontaneous intrinsic ferrovalley material with a room temperature of 334 K and an obvious valley splitting of 32 meV. Due to the non-zero valley-contrast Berry curvature, monolayer CeBr 2 is a candidate materials for realizing the anomalous valley Hall effect under a suitable applied electric field. Our study provides a theoretical reference for the design of valley electronic devices with anomalous valley Hall effect based on hole-doped CeX 2. [ABSTRACT FROM AUTHOR]

Due to geological processes such as sedimentation, tectonic movement, and backfilling, natural soil often exhibits characteristics of rotated anisotropy. Recent studies have shown the significant impact of rotated anisotropy on slope stability. However, little research has explored how this rotated anisotropy affects the large deformations occurring after slope failure. Therefore, this study integrates rotated random field theory with smoothed particle hydrodynamics (SPH) to investigate its influence on post‐failure slope behavior. Focusing on a typical slope scenario, this research utilizes graphics processing unit (GPU)–accelerated covariance matrix decomposition (CMD) method to create rotated anisotropy random fields and applies the SPH framework for analysis. It examines the influence of rotated anisotropy angles and the cross‐correlation between cohesion and internal friction angle on landslides. The results indicate that the rotational anisotropy of the slope significantly influences post‐failure behavior. When the rotation angle is close to the slope surface, it tends to amplify both the magnitude and variability of slope failure. Furthermore, the study evaluates the efficiency of generating these random fields and emphasizes the substantial computational speed improvements achieved with GPU acceleration. These findings offer a robust approach for probabilistic analysis of slope large deformations considering rotated anisotropy. They provide a theoretical foundation for accurately assessing the risk of slope collapse, holding significant practical implications for geotechnical engineering. [ABSTRACT FROM AUTHOR]

An ancient landslide located in Xichang, China, that was reactivated by mining excavation and rainfall was investigated in this study. The volume of the reactivated landslide was approximately 1200 × 104 m3, thus posing a major threat to the mining area's safety. Field surveys, drilling, on-site monitoring, laboratory studies, and numerical analyses were performed to investigate the landslide deformation characteristics and reactivation mechanism. The reactivated landslide was divided into four zones: the leading-edge collapse, the sliding, the uplifting, and the traction sliding zones. X-ray diffraction and ring shear tests indicate that the sliding zone soil exhibits significant strength-weakening characteristics when exposed to water, and the residual cohesion and internal friction angle decrease by 26.9% and 28.9%, respectively, as the moisture content increases from 15 to 24%. Additionally, a three-dimensional numerical simulation was conducted to quantitatively analyze the stability evolution of the landslide. The results showed that the topographic, stratigraphic lithology, and sliding zone soil properties provided the basic conditions for landslide formation, while mining excavation and concentrated rainfall triggered landslide reactivation. Furthermore, a conceptual model characterizing the reactivation process was constructed, and the reactivation process was divided into five stages: leading-edge collapse, sliding, extrusion and bulging, deformation expansion, and accelerated creep deformation. This study provides a basis for understanding the reactivation mechanism of ancient open-pit mine landslides. [ABSTRACT FROM AUTHOR]

The rapid progress of urbanization and industrialization has led to the accumulation of large amounts of metal ions in the environment. These metal ions are adsorbed onto the negatively charged surfaces of clay particles, altering the total surface charge, double-layer thickness, and chemical bonds between the particles, which in turn affects the interactions between them. This causes changes in the microstructure, such as particle rearrangement and pore morphology adjustments, ultimately altering the mechanical behavior of the soil and reducing its stability. This study explores the effects of four common metal ions, including monovalent alkali metal ions (Na+, K+) and divalent heavy metal ions (Pb2+, Zn2+), with a focus on how ion valence and concentration impact the soil's microstructure and mechanical properties. Microstructural tests show that metal ion incorporation reduces particle size, increases clay content, and transforms the structure from layered to honeycomb-like. Small pores decrease while large pores dominate, reducing the specific surface area and pore volume, while the average pore size increases. Although cation exchange capacity decreases, cation adsorption density per unit surface area increases. Monovalent ions primarily disperse the soil structure, while divalent ions induce coagulation. Macro-mechanical tests reveal that metal ion contamination reduces porosity under loading, with compressibility rises as the ion concentration increases. Soils contaminated with alkali metal ions shows higher compression coefficients at all loads, while heavy metal ions cause higher compression under lower loads. Shear strength, the internal friction angle, and cohesion in metal-ion-contaminated clay decrease compared to uncontaminated field-state clay, with greater declines at higher ion concentrations. The Micropore Morphology Index and hydro-pore structural parameter effectively characterize both micro- and macrostructural properties, establishing a quantitative relationship between HPSP and the engineering properties of metal-ion-contaminated clay. [ABSTRACT FROM AUTHOR]

In cold regions, the extensive distribution of silt exhibits limited applicability in engineering under freeze–thaw cycles. To address this issue, this study employed rice husk carbon and calcium lignosulfonate to stabilize silt from cold areas. The mechanical properties of the stabilized silt under freeze–thaw conditions were evaluated through unconfined compressive strength tests and triaxial shear tests. Additionally, scanning electron microscopy was utilized to analyze the mechanisms behind the stabilization. Ultimately, a damage model for rice husk carbon–calcium lignosulfonate stabilized silt was constructed based on the Weibull distribution function and Lemaitre's principle of equivalent strain. The findings indicate that as the content of rice husk carbon and calcium lignosulfonate increases, the rate of improvement in the compressive strength of the stabilized silt progressively accelerates. With an increase in the number of freeze–thaw cycles, the deviatoric stress of the stabilized soil gradually diminishes; the decline in peak deviatoric stress becomes more gradual, while the reduction in cohesion intensifies. The decrease in the angle of internal friction is relatively minor. Microscopic examinations reveal that as the number of freeze–thaw cycles increases, the soil pores tend to enlarge and multiply. The established damage model for stabilized silt under freeze–thaw cycles and applied loads demonstrates a similar pattern between the experimental and theoretical curves under four different confining pressures, reflecting an initial rapid increase followed by a steady trend. Thus, it is evident that the damage model for stabilized silt under freeze–thaw conditions outperforms traditional constitutive models, offering a more accurate depiction of the experimental variations observed. [ABSTRACT FROM AUTHOR]

Using coal gangue as subgrade filler (CGSF) can address the accumulated issues of coal mine waste, but also save the constructing costs, which has the important ecological and engineering practical value. The well-graded limit of CGSF was captured based on the fractal model grading equation (FMGE). The large-scale vibration compaction test (LCT) shows that particle grading has a remarkable influence on the compaction of CGSF, with the increase of fine particle content, the dry density of sample first increases and then decreases. On this basis, the optimal range of particle grading was obtained. A series of large-scale triaxial tests (LTT) were conducted to investigate the mechanical behaviors of CGSF. The results shown that (1) the peak deviatoric stress shows a well-quadratic correlation with the fractal dimension. The optimal grading range of CGSF captured by LTT and LCT is basically the same, hence the suggestion of acquiring the optimal grading through LCT was given. (2) Increasing the compaction degree (DC) can significantly improve the strength of CGSF if DC is smaller, while when DC is greater, the strength improved by increasing DC will not be significant. (3) The grading and DC have a significant impact on the cohesive force of CGSF, while have little effect on internal friction angle. In addition, the research results provide good guidance for the constructing of a highway subgrade in practice. [ABSTRACT FROM AUTHOR]

Projects related to Geotechnical Engineering require thorough ground study to know the soil behaviour thus making it necessary to determine the strength and stability parameters of soil. The soils of Assam are primarily of four types viz., Alluvial (old and new), Piedmont, Hill and Lateritic soils with the alluvium abundantly available in the state. The most important soil parameters are the shear strength parameters, namely, cohesion (c) and angle of internal friction (Φ) which can be obtained using triaxial tests with different drainage conditions. But one triaxial test may take weeks to complete and are very expensive. Moreover, for large projects it is practically preposterous to conduct large number of triaxial tests. Hence, an alternate way is to develop a relation between different parameters which enable us to determine others. The main objective of this study is establishing prediction models that allow the shear parameters to be predicted from soil index properties. For this, three prediction models are developed by combining various soil parameters viz., Liquid Limit (LL), Plastic Limit (PL), Specific Gravity (G) and Optimum Moisture Content (OMC) using Multivariate Regression Analysis (MRA) and Artificial Neural Network (ANN). The results show better performance for ANN than MRA. [ABSTRACT FROM AUTHOR]

The reactivation mechanism of multi-slide landslides entails high complexity, and the shear mechanical properties of high groundwater-level landslides are crucial for analyzing the formation mechanism of reactivated landslides. Taking the K39 landslide of Wenma Expressway in Yunnan Province as the research object, we identified the geological and hydrogeological conditions of the landslide, the physical and mechanical properties of the slip zone soil, and the landslide deformation law using geological mapping, geotechnical engineering, indoor testing, and in situ monitoring. The results show the landslide exhibited alternating acceleration and deceleration movements under seasonal heavy rainfall and high groundwater levels. The shear strength of the soil in the deep sliding zone was greater than that of the soil in the shallow sliding zone. The deep and shallow sliding zone soils showed a decrease in shear strength with increased water content. Moreover, the residual strength of the deep sliding zone soil displayed a negative rate with an increased shear rate. In contrast, the residual strength of the shallow sliding zone soil exhibited a positive rate. Furthermore, under different shear rates, the residual internal friction angle and cohesion of the deep sliding zone soil decreased with increased water content, whereas only the residual internal friction angle of the shallow sliding zone soil followed this pattern. Finally, we performed a sensitivity analysis using the GA-BP neural network for the ring shear test parameters of the deep and shallow sliding zone soils, which included consolidation pressure, water content, and shear rate. Our analysis revealed that the residual strength of deep sliding zone soils is most affected by water content, whereas the residual strength of shallow sliding zone soils is most affected by consolidation pressure. Furthermore, it was found that the effect of water content on residual strength is much greater than the effect of shear rate on residual strength for both deep and shallow sliding zone soils. The study results contribute to a unified understanding of how shear rate affects residual strength mechanisms, support research on shear mechanical properties for multiple landslide revivals, and inform engineering practices and policies in landslide-prone areas. [ABSTRACT FROM AUTHOR]

Dredged soils possessing low-bearing capacity and high compressibility were tested incorporating waste rubber tyre powder (WRTP) at varying percentages in increments of 1.5% up to 15% by dry weight of the soil and 2% cement. It was observed that maximum dry unit weight (MDUW) decreased to 11.75 and 12 kN/m3 for combinations of 15% WRTP and 15% WRTP + 2% cement respectively. Direct shear test (DST) parameter 'c' at 4.5% WRTP and 2% cement increased from 44 to 49 kN/m2 whereas angle of internal friction, 'ϕ' showed an increase up to 37°. The Unconfined compressive strength (UCS) of soil-WRTP-cement mixture enhanced from 110 kN/m2 in the untreated state to 596 kN/m2 at 28 days curing and 6% WRTP + 2% cement. Further, California bearing ratio (CBR) values increased up to an optimum addition of 6% WRTP + 2% cement, both in unsoaked (6 to 13%) and soaked condition (2 to 7%). Soil improvement using WRTP and cement can improve the strength and durability of road subgrades and embankments. WRTP in addition to cement can be used in locations with weak or problematic soils to improve load-bearing capacity and reduce settlement-related problems. [ABSTRACT FROM AUTHOR]

The scotch yoke inerter (SYI) is a new geometrically nonlinear vibration isolator with a smaller maximum transmissibility than linear inerter systems. The influence of internal friction and the damping effect on the response of the SYI system for seismic isolation can be significant and needs to be studied. In this study, a small-scale SYI is designed and tested, and an accurate model of SYI is developed for describing its dynamic behavior. Then, the motion equation of the coupled structure-SYI system is established, and several dynamic analyses are studied, including the amplitude-frequency response, the critical excitation amplitude, the backbone curve, the peak response, the starting frequency, and the linearization design, and many fitting expressions for engineering applications are proposed. Finally, the vibration isolation performance of SYI is investigated when friction and damping effects are considered or not, using a single-degree-of-freedom system and a building structure as examples. For harmonic excitations, the maximum transmissibility of the SYI system is superior to that of the linear inerter system, and its advantage becomes more obvious as the excitation amplitude increases. Its seismic isolation effect is slightly better than that of a linear inerter for seismic excitations, where the SYI considering friction and damping effects is better. Practical Applications: A scotch yoke inerter is a geometrically nonlinear inerter that is simple to construct, easy to implement, and has the advantage of variable inertance. The variation of inertance is reflected in two aspects: first, its nominal inertance can be changed by adjusting the location of the pin; second, its dynamic inertance is related to its deformation, which can provide greater negative stiffness effects for larger external excitations. The precise and simplified output force model of the scotch yoke inerter is provided, which can be applied to the calculation and verification of the output force in the design of scotch yoke inerters. Fitting expressions for the critical excitation amplitude, starting frequency, and linearization design are proposed, which can provide a theoretical basis for the application of scotch yoke inerters in base-isolated structures. Compared with traditional linear inerters, scotch yoke inerters have a better isolation control effect, and this control effect can be further improved by making reasonable use of the internal friction and the damping in SYI. [ABSTRACT FROM AUTHOR]

Soils in the site are usually layered due to natural sedimentation, which causes nonuniformity along the depth. Conventional upper bound limit analysis is no longer suitable for analyzing such slope stability issues; hence, an alternative approach is required. To account for varying soil properties, including internal friction angle, cohesion, unit weight, and limit bonding strength at the soil–nail interface among different soil layers, the discretized technique was introduced to generate a potential failure mechanism. Considering the influence of soil parameters within the depth on the failure mechanism, three failure modes were employed to carry out the upper bound limit analysis of soil-nailed slope stability, including toe failure mode, intermediate failure mode, and bellow-toe failure mode. The upper bound solutions of the factor of safety and failure surface were determined by the strength reduction technique in combination with the particle swarm optimization algorithm. A finite-element limit analysis model of soil-nailed slopes in a layered ground by Optum G2 (version 2023 2.3.7) was established to verify the proposed upper bound limit analysis method. The results of the discretized technique were compared with those from the conventional upper bound analysis, the shear strength reduction finite-element method and limit equilibrium method in previous literature, and the finite-element limit analysis by Optum G2. To better estimate the influences of the soil nail inclination angle and soil thickness ratio H1/H on the factor of safety and critical failure surface, a parametric study was performed under two cases: a hard soil layer or a soft soil layer in the upper part of the ground. To evaluate the contribution of soil nails to slope stability, a dimensionless parameter η, meaning the ratio of the energy dissipation rate of soil nails to the total energy dissipation rate, was proposed and discussed in the parametric analysis. The results showed that the proposed discretized method agrees well with the shear strength reduction finite-element method, limit equilibrium method, and finite-element limit analysis (FELA). The simplified approach with weighted average parameters has a relative error greater than 10% and is not appropriate for stability analysis in the layered ground compared with the proposed discretized method and FELA. [ABSTRACT FROM AUTHOR]

Accurate analysis of the deformation characteristics and the damage destruction mechanism of a rock mass is a prerequisite for the evaluation of the stability of the surrounding rock in tunnel engineering. This paper proposes a combination of numerical simulation techniques based on microstructure analysis and physical model experimental methods, which allows for the microscale interpretation of macroscale experimental phenomena and provides new insights for further summarizing the instability and failure patterns of rocks under unloading paths. To investigate the macroscopic and microscopic failure mechanisms as well as the damage deterioration patterns of granite under unloading conditions, physical model tests were conducted using stress paths of conventional triaxial and constant axial pressure unloading confining pressure. The experiments encompassed unloading paths, and the associated mechanical responses were finely simulated using the particle flow code method coupled with digital image processing techniques. The results reveal that at lower unloading rates, granite predominantly undergoes shear failure, with the destabilizing mechanism attributed to the formation of an "X"-shaped conjugate failure surface under the influence of tension–shear coupling. As the unloading rate increases, tensile forces progressively take precedence, leading to more pronounced brittle failure characteristics in granite. The ratio of the confining pressure reduction to the initial confining pressure at the point of specimen failure increases with the unloading rate and decreases with the initial confining pressure. Faster unloading rates correspond to a more rapid increase in Poisson's ratio, and the unloading path primarily influences the lateral strain variation during the initial stages of unloading. Additionally, under unloading conditions, the internal friction angle of granite increases, while the cohesion decreases. The impact of unloading rate and path on cohesion becomes more pronounced. The findings of this research have certain reference value for further optimizing the methods for assessing the stability of rock masses surrounding tunnels. [ABSTRACT FROM AUTHOR]

The deterioration of shear resistance in rock and soil masses has resulted in numerous severe natural disasters, highlighting the significance of long-term monitoring for disaster prevention and mitigation. This study explores the use of a nondestructive method to quickly and accurately evaluate the shear properties of soil-rock mixture. The shear stress, shear strain, and resistivity of the soil-rock mixture were tested simultaneously using a combination of direct shear and resistivity tests. The test results show that the resistivity of the soil-rock mixture gradually decreases with increasing shear strain. The resistivity of all specimens ranged approximately from 60 to 130 Ω.m throughout the shear process. At the end of the shear test, the vertical failure resistivity showed an irregular "W" shape with increasing rock content. It exhibited a significant negative linear functional relationship with the shear strength. With reference to the determination of cohesion and internal friction angle on the shear strength envelope, the horizontal angle of the vertical failure resistivity-normal stress curve is defined as the resistivity angle, and the intercept of the curve is the resistivity at the initial moment of shear. It has been observed that the resistivity angle is negatively and linearly correlated with the internal friction angle. At the same time, there is a linear growth relationship between resistivity at the initial moment of shear and cohesion. It has been demonstrated that an increase in rock content contributes to a general escalation in both the average structure factor and average shape factor. Meanwhile, a decrease in the anisotropy coefficient has also been noted. These alterations are indicative of the extent of microstructural transformations occurring during the deformation process of the soil-rock mixture. The research results verify the feasibility of real-time deformation monitoring and characterization of shear strength parameters using resistivity. [ABSTRACT FROM AUTHOR]

Enhancing soil shear strength is of great importance in preventing soil collapse and erosion in the hilly granitic region of southern China. However, limited studies have been conducted on improving soil shear strength in collapsing gullies. Electrokinetic stabilization (EKS) involves applying an electrical current through a soil mass to promote the migration of chemicals from injection points, thereby altering the chemical composition of the treated soil to improve its physical properties. In this study, we investigated the effects of adding calcium chloride (CaCl2) and using EKS techniques on the soil shear characteristics (shear strength and its two components: cohesion and internal friction angle) of three different soil layers in collapsing gullies. The results showed that the EKS techniques significantly increased the migration of calcium ions from the anode to the cathode region of the power supply device used in the soils. Using the EKS process alone did not increase or even decrease the soil shear strength, but combining EKS with CaCl2 injection (Ca-EKS) increased the soil shear strength, and this increase was mainly due to the increase in soil cohesion. The soil cohesion after Ca-EKS treatment increased on average by 49.84%, 83.11% and 100.36% compared with the soil without treatments (CK) for the red soil, sandy soil and detritus, respectively. However, soil amended only by CaCl2 addition, Water-EKS or Ca-EKS does not show an increase in soil internal friction angles compared with the CK. These results demonstrate that Ca-EKS can be applied to improve the soil shear strength and stability of gully walls in hilly granitic regions. [ABSTRACT FROM AUTHOR]

The utilization of artificial ground-freezing techniques is increasingly prevalent in the construction of water-diversion tunnels. The inadequate mechanical properties of weakly consolidated mudstone (WCM) pose significant challenges for tunneling construction. In this study, a series of triaxial shear tests were conducted on frozen specimens of WCM to elucidate its shear strength characteristics. The experiment involved four freezing temperatures (0, −5, −10, and −20 °C) and four confining pressures (1, 2, 3, and 4 MPa). The results indicate that the shear failure mode of the WCM exhibits distinct shear zone failure characteristics under artificial freezing conditions, particularly prominent in the lower temperature environments. As the freezing temperature gradually decreases, there is a substantial increase of over 200% in the shear strength of frozen specimens, accompanied by a corresponding decrease in yield strain. Furthermore, the cohesion and internal friction angle of frozen WCM increase as the freezing temperature decreases, following a complex exponential function relationship rather than a linear one. As the freezing temperature decreases from 0 °C to −20 °C, there is an increase in cohesion and internal friction angle from 1012 kPa to 1425 kPa, accompanied by a rise in the internal friction angle from 43.2° to 58.1°. Notably, the application of confining pressure exerts a pronounced influence on the shear strength of frozen WCM, with elevated levels of confining pressure resulting in a substantial augmentation of the shear strength. The failure mode of frozen WCM is significantly influenced by freezing temperatures. At low temperatures, the specimen of mudstone exhibits a shear failure behavior, while at high temperatures, it predominantly demonstrates expansion failure. This phenomenon can be attributed to the increased brittleness of specimens caused by ice crystals, rendering it more susceptible to brittle failure under shearing forces. These findings signify an enhancement in the mechanical behavior of WCM within the tunnel sidewall under artificial freezing conditions. [ABSTRACT FROM AUTHOR]

Accurate soil stratification is crucial for levee safety evaluation, yet limited field sampling often hinders comprehensive analysis. This study applies the Partitioning Around Medoids (PAM, also known as K-Medoids) clustering approach for levee soil stratification using data from multiple probe drilling sites. Focusing on a Yellow River levee section in China as a study case, the PAM clustering approach effectively identifies its distinct soil types and reconstructs its soil stratification by analyzing key soil properties relevant to levee seepage and stability characteristics, including coefficient of permeability, angle of internal friction, and cohesion. The resulting soil stratification, when applied to seepage and stability analyses of the levee section, yields relatively high safety factors, indicating low failure risks under design flood conditions. These analytical results align with recent monitoring records, validating the effectiveness of the approach. A sensitivity analysis on the number of clusters, the key parameter in the PAM clustering approach, demonstrates the typical existence of an optimal value balancing computational accuracy and practical interpretability. A comparison with a hierarchical clustering approach further confirms the robustness of the PAM clustering approach. This study contributes to improving levee soil stratification methodology and enhancing levee safety evaluation, particularly when dealing with limited and spatially distributed sampling data. [ABSTRACT FROM AUTHOR]

Waste slurry is a major component of construction waste, and its resource utilization can effectively reduce its environmental impact. The effect of polyacrylamide (PAM) content and moisture content on the strength characteristics of PAM modified cement stabilized construction waste slurry (PCMS) was studied using unconfined compressive strength (UCS) and triaxial tests. It can be concluded that, 1) The UCS of PCMS increases with the increase of curing age and significantly decreases with the increase of moisture content. As the content of PAM increases, it first increases and then decreases, with UCS reaching its maximum at a PAM content of 0.5%. 2) When the moisture content is 50%, PAM can increase the elastic modulus of PCMS. When the content of PAM is 0.5%, the elastic modulus reaches its maximum value. When the moisture content is 80% and 100%, the effect of PAM on the elastic modulus of PCMS is not significant. 3) The addition of PAM can improve the shear strength of PCMS. Under the same confining pressure, the shear strength of PCMS increases first and then decreases with the increase of PAM content, and the optimal content is 0.5%. 4) The variation pattern of PCMS cohesion is basically consistent with the shear strength. PAM improves the shear strength of PCMS by enhancing its cohesion. The addition of PAM has a relatively small impact on the internal friction angle of PCMS. These findings provide valuable insights for research into modification technology and the resource utilization of construction waste slurry. [ABSTRACT FROM AUTHOR]

Studying the effects of weathering on the mechanical properties and microscopic evolution of weathered granite soil (WGS) is essential for connecting microstructure with macroscopic behavior. This study conducts systematic monotonic and cyclic triaxial tests, along with a series of microscopic tests on WGS samples, to explore the influence of weathering on WGS mechanical properties and the mechanism of granite weathering. Results indicate that both effective internal friction angle and effective cohesion decrease progressively with increased weathering. Completely weathered granite (CWG) exhibits greater dynamic strength compared to granite residual soil (GRS). Additionally, as weathering progresses, quartz fragments are lost, while feldspar and biotite weather to form secondary minerals such as kaolinite and illite, leading to an overall enrichment in aluminum and iron in the granite. Weathering causes structural deterioration of WGS. Finally, the mechanical parameters of WGS and their chemical weathering indices show a coefficient of determination ranging from 60 to 99%. This study helps elucidate the fundamental causes of performance changes in WGS, thereby optimizing engineering design and enhancing disaster prediction accuracy, while providing new research perspectives and experimental evidence for WGS. [ABSTRACT FROM AUTHOR]

This study evaluates the performance of a geosynthetic reinforced soil integrated bridge system (GRS-IBS) in terms of total displacement by varying different design parameters simultaneously and also suggests optimum values of them. These parameters include, i. backfill internal friction angle (çb) and reinforcement spacing (Sv), ii. Backfill internal friction angle (çb) and geogrid axial stiffness (EA) at varying reinforcement spacing (Sv), iii. Backfill internal friction angle (çb) and number of bearing bed layers, and the effect of retained backfill slope (mb). Simulations were conducted using PLAXIS 2D software. Analysis showed that the cumulative effect of these parameters had a significant effect on total displacement but after a certain point increase or decrease in their values showed no effect on the results while some parameters showed negligible effect on the deformation of the wall. Furthermore, due to the notable effect of çb, Sv and EA on the total displacement of the wall, the impact of these parameters was also investigated on the development of tensile force in the topmost layer of geogrid in GRS IBS. It was noted that the shape of the tensile force distribution graph was the same for all the cases and the order of the parameters in terms of their effect on tensile force was Sv > çb > EA. Also, a detailed analysis of tensile force development in all the layers of geogrids showed that if Sv = 0.2 m, the spacing between reinforcement in the lower portion of GRS IBS can be increased as these layers showed approximately zero tensile load. [ABSTRACT FROM AUTHOR]

Particle shape is an important factor affecting the strength and deformation of coarse materials in dumps. However, conducting research on particle shape in current laboratory experiments, and there exists no classification standard for the particle shape of the dump. Considering the project on high-bench dump in Jiangxi Province, based on the random particle construction method, this study determined the characteristic particles of coarse grain material in the dumping site by combining field investigation results, large-scale direct shear tests, and numerical analysis. Further, the influence mechanism of coarse grain content and characteristic particles on the mechanical characteristics of the dump were analyzed. The results showed that the increase in coarse grain content enhanced the irregularity of particle shape, increased the internal friction angle between particles, and reduced the cohesion of the dump. Moreover, with increase in the normal stress, the shear strength changed from insignificant to gradually enhanced, although the increasing trend slowed down. The constructed random particle model can well solve the effects of occlusion, nesting, and friction between particles that is neglected by the standard spherical particle model, and the fitting degree is better. The particle characteristics of coarse-grain materials in the dump were primarily block, strip, and flake. The three types of shape characteristics under low normal stress did not affect the mechanical properties of the dump. Further, with the increase in normal stress, the stress-strain curve reflected the shape characteristics and content of the dominant characteristics in the dump. Specifically, the block sample exhibited the dominant characteristics and the most content under the same normal stress, followed by the strip sample, with the flake sample exerting the least influence. The research results provide a theoretical basis for long-term safe operation, disaster monitoring, and early warning of high bench dump. [ABSTRACT FROM AUTHOR]

Subhalo dynamics in galaxy cluster host halos govern the observed distribution and properties of cluster member galaxies. We use the IllustrisTNG simulation to investigate the accretion and orbits of subhalos found in cluster-size halos. We find that the median change in the major axis direction of cluster-size host halos is approximately 80° between a ∼ 0.1 and the present day. We identify coherent regions in the angular distribution of subhalo accretion, and ∼68% of accreted subhalos enter their host halo through ∼38% of the surface area at the virial radius. The majority of galaxy clusters in the sample have ∼2 such coherent regions. We further measure angular orbits of subhalos with respect to the host major axis and use a clustering algorithm to identify distinct orbit modes with varying oscillation timescales. The orbit modes correlate with subhalo accretion conditions. Subhalos in orbit modes with shorter oscillations tend to have lower peak masses and accretion directions somewhat more aligned with the major axis. One orbit mode, exhibiting the least oscillatory behavior, largely consists of subhalos that accrete near the plane perpendicular to the host halo major axis. Our findings are consistent with expectations from inflow from major filament structures and internal dynamical friction: most subhalos accrete through coherent regions, and more massive subhalos experience fewer orbits after accretion. Our work offers a unique quantification of subhalo dynamics that can be connected to how the intracluster medium strips and quenches cluster galaxies. [ABSTRACT FROM AUTHOR]

Spherical glass beads weaken the influences of particle morphology, surface properties, and microscopic fabric on shear strength, which is significant for revealing the relationship between macroscopic particle friction mechanisms and the particle size distribution of sand. This paper explores the shear mechanical properties of glass beads with different particle size ratios under different confining pressures. It obtains the particle size ratio and fractal dimension D through an optimal mechanical response. Simultaneously, we explore the range of the fractal dimension D under well-graded conditions. The test results show that the strain-softening degree of Rs is more obvious under a highly effective confining pressure, and the strain-softening degree of Rs can reach 0.669 when the average particle size d ¯ is 0.5 mm. The changes in the normalized modulus ratio Eu/Eu50 indicate that the particle ratio and arrangement are the fundamental reasons for the different macroscopic shear behaviors of particles. The range of the peak effective internal friction angle φ is 23 °~35 °, and it first increases and then decreases with the increase in the effective confining pressure. As the average particle size increases, the peak stress ratio MFL and the peak effective internal friction angle φ first increase and then decrease, and both can be expressed using the Gaussian function. The range of the fractal dimension D for well-graded particles is 1.873 to 2.612, and the corresponding average particle size d ¯ ranges from 0.433 to 0.598. Under the optimal mechanical properties of glass beads, the particle size ratio of 0.25 mm to 0.75 mm is 23:27, and the fractal dimension D is 2.368. The study results provide a reference for exploring friction mechanics mechanisms and the optimal particle size distributions of isotropic sand. [ABSTRACT FROM AUTHOR]

Lubricin, secreted primarily by chondrocytes, plays a critical role in maintaining the function of the cartilage lubrication system. However, both external factors such as friction and internal factors like oxidative stress can disrupt this system, leading to osteoarthritis. Inspired by lubricin, a lubricating nanozyme, that is, Poly‐2‐acrylamide‐2‐methylpropanesulfonic acid sodium salt‐grafted aminofullerene, is developed to restore the cartilage lubrication system using an "In‐Out" strategy. The "Out" aspect involves reducing friction through a combination of hydration lubrication and ball‐bearing lubrication. Simultaneously, the "In" aspect aims to mitigate oxidative stress by reducing free radical, increasing autophagy, and improving the mitochondrial respiratory chain. This results in reduced chondrocyte senescence and increased lubricin production, enhancing the natural lubrication ability of cartilage. Transcriptome sequencing and Western blot results demonstrate that it enhances the functionality of mitochondrial respiratory chain complexes I, III, and V, thereby improving mitochondrial function in chondrocytes. In vitro and in vivo experiments show that the lubricating nanozymes reduce cartilage wear, improve chondrocyte senescence, and mitigate oxidative stress damage, thereby mitigating the progression of osteoarthritis. These findings provide novel insights into treating diseases associated with oxidative stress and frictional damage, such as osteoarthritis, and set the stage for future research and development of therapeutic interventions. [ABSTRACT FROM AUTHOR]

Research on geosynthetic-reinforced soil (GRS) walls in tiered configurations is increasing gaining attention, with numerical methods being predominantly used in the past. In recent years, there has been a growing trend in conducting shaking table tests to further explore this area. However, traditional limit equilibrium (LE) methods are more preferred for design purposes. This study utilized a modified top-down approach, which is based on LE and pseudo-static methods to investigate the horizontal seismic force on the distribution of required tension along each reinforcement layer. The approach is initially extended from static analysis to seismic analysis for multitiered GRS walls. Parametric analyses are conducted to study the impacts that horizontal seismic coefficient, reinforcement length and spacing, internal friction angle of soil, height ratio of upper/lower tier, offset distance have on the internal stability of two-tiered GRS walls. Meanwhile, influences of wall batter and number of tiers on the critical offset distance for different seismic coefficients are assessed. Results indicate that the internal stability differs between the upper and lower tiers under seismic conditions, particularly with higher seismic forces, where the lower tier requires greater reinforcement tension to enhance its stability. Additionally, the critical offset distance grows with the increase in seismic coefficient, and it is sensitive to the internal friction angle of soil and the height ratio. • An approach based on the top-down method which is modified to calculate the distribution of required reinforcement tension of multitiered GRS walls under seismic conditions is proposed. • An in-depth seismic analysis of the internal stability of GRS walls in tiered configurations is first conducted. • Impacts of horizontal seismic coefficient, reinforcement length and spacing, internal friction angle of soil, offset distance, and height ratio of upper and lower tiers are investigated. • The variation of critical offset distance under various seismic coefficients and wall parameters is revealed. [ABSTRACT FROM AUTHOR]

Mountainous regions are often characterized by the presence of V-shaped gullies, necessitating the construction of retaining structures to support the embankments spanning across these gullies. The gully topography renders conventional two-dimensional soil pressure calculation theory unable to meet the stability requirements for the design of retaining walls (RWs) in mountainous gullies. To address this issue, the sliding bodies of V-shaped gully retaining walls have been identified as high-wall type and low-wall type, and the spatial earth pressure of V-shaped RWs has been determined using the horizontal differential layer method. Combined with numerical simulation, a systematic parametric study is conducted to reveal the impact of the fill-soil internal friction angle, wall–soil contact surface roughness, wall height-to-width ratio, and valley side-slope angle on the active earth pressure acting on the wall. The magnitude of internal friction angle of the fill and the side-bank angle significantly influence the horizontal earth pressure. However, for RWs with finite length along their longitudinal direction, the active earth pressure value at the wall ends is significantly lower than values computed under two-dimensional plane-strain conditions. Moreover, the resultant active force point is located in the range of H/3−H/2 from the wall bottom, where H = wall height, which shows that considering three-dimensional effects is significant. [ABSTRACT FROM AUTHOR]

The tensile strength is an important parameter in engineering. Many engineering-related problems in buildings as well as the damage caused to them during natural disasters occur owing to a lack of tensile strength. The unconfined penetration (UP) test is an indirect method to measure the tensile strength of soil. Analyses of the mechanism of the UP test and simulations based on the discrete-element method have shown that the UP test is a complex process involving tensile and shear strengths. In this study, the authors use the modified Mohr–Coulomb model to establish a joint criterion for the failure of the tensile strength and the shear strength of loess, and derive expressions for the correlations between the relevant mechanical parameters. A combination of the results of the aforementioned model and laboratory tests showed the following: (1) the process of failure of loess samples during the UP test consisted of four stages: (I) the shaping of the wedge-shaped split body, (II) tension-induced fracture, (III) the yield stage, and (IV) damage to the sample; (2) the tensile strength of the loess decreased exponentially with its saturation; (3) the ratio of the unconfined compressive and cohesive strengths to the tensile strength of the remolded loess was 1.37 times that of the undisturbed loess, while the ratio of the unconfined compressive strength of remolded loess to its cohesion was similar to that of undisturbed loess; (4) the wedge-splitting angle ranged from 13° to 23°, and had a negative correlation with the internal angle of friction, a positive correlation with the water content, and decreased exponentially with the tensile strength. [ABSTRACT FROM AUTHOR]

Mining operations generate a significant quantity of mining waste in the form of sterile rocks and processing residues. These mining wastes are typically placed on the surface and can cause geotechnical and geochemical disturbances, as well as contaminants in surface water (through runoff) and groundwater (through infiltration), thus posing environmental risks. This article aimed to characterize the geotechnical properties of lead-silver ore processing residues at the Auzelles site in order to assess their stability and propose recommendations for their management and rehabilitation. The adopted methodology included in situ tests (such as density measurement and permeability) and laboratory analyses (grain size distribution, moisture content, methylene blue test, direct shear test, and standard Proctor test). The results showed a wet density of 1.63 g/cm2 for the residues compared with 1.65 g/cm3 for the waste rock, as well as a permeability of the residues measured at 5.5 × 10-5 m/s, indicating significant drainage capacity. Laboratory analyses revealed that the samples were primarily composed of very silty sands and gravel, classified as B5 according to the Guide to Road Settlements. The cohesion of the residues was found to be zero, while the internal friction angle varied between 28° for the residues and 30° for the foundation soils. These geomechanical properties, particularly density, lack of cohesion, and friction angle values, raise concerns about the long-term stability of the residues. Due to their high permeability and lack of cohesion, the residues are susceptible to mass movement and erosion, which may exacerbate contamination risks. Therefore, it is essential to integrate these parameters into any potential residue stability analysis. Proactive management, based on these results, requires the implementation of appropriate rehabilitation techniques, such as drainage optimization and incorporation of vegetation covers, to minimize environmental impacts and ensure the long-term sustainability of mining waste structures. [ABSTRACT FROM AUTHOR]

Ensuring the stability of slopes is critical to the safe operation of geotechnical engineering. Evaluating slope stability to minimize geologic risks induced by destabilization is significant in reducing casualties and property damage. A conventional, single-coefficient strength reduction method is widely applied in slope stability analyses, but this method ignores the attenuation degree of different parameters in the slope destabilization. A new double-strength reduction method considering different contributions of the mechanics' parameters is proposed in this study for evaluating the stability of nonhomogeneous slope. First, the role of each mechanic's parameters in the slope destabilization was investigated theoretically and numerically using ABAQUS software 2022. The results indicate that the effect of elasticity (E), Poisson's ratio (v), and soil gravity (γ) on the evolution of factor of safety (FOS) are insignificant and can be neglected compared with cohesive force (c), and angle of internal friction (φ). Next, an improved method was constructed to correlate the FOS with cohesive force (c) and the angle of internal friction (φ). Then, a numerical method was constructed based on the computation of the mathematical–mechanical relationship between FOS and the mechanical parameters, and the stability of slope is estimation based on the Mohr–Coulomb yield criterion. Finally, the double-strength reduction coefficient method proposed in this study, the limit equilibrium method, and the traditional finite element strength reduction coefficient method were applied to nonhomogeneous slopes and slopes containing a soft underlying layer for comparison, and the difference between them was within the range of ±5%. The results indicate that both the limit equilibrium method and the traditional finite element strength reduction method tend to overestimate the FOS of intricate slopes compared with the evaluated method proposed in this study. This parallel comparison serves to validate the accuracy of the double-strength reduction method proposed in the present study. Further, based on the proposed method, the relationship between slope stability and slope displacement is established, which provides a theoretical basis for the safety assessment of slope engineering. [ABSTRACT FROM AUTHOR]

When an earth pressure balance shield passes through soft-upper and hard-lower composite strata, it faces challenges such as cutterhead "mud cake" formation, inefficient muck removal, and tool wear. To address these issues, this study focused on silty clay-completely weathered granite composite strata and conducted laboratory tests on ground conditioning in different strata based on the adaptability and performance of soil conditioners. The study explored the effects of soil conditioners, such as foam agent and bentonite slurry, as well as their improvement methods on soft-upper and hard-lower strata, to determine an optimal ground conditioning scheme and the appropriate addition ratios for shield tunneling in composite strata. The results showed that: (1)Combining a 3% concentration foam agent solution with bentonite slurry at a 1 : 8 ratio yielded good results. (2)The silty clay strata were improved by foam agent. The slump of the muck increased with the foam addition ratio, while the shear strength, cohesion, internal friction angle, and permeability coefficient decreased. The optimal addition ratio of the soil conditioners was between 19. 7% and 22. 8%. ( 3) The completely weathered granite strata were improved using a combination of foam agent and bentonite slurry, which effectively enhanced the flow plasticity and impermeability of the muck. When using only foam, the optimal addition ratio was between 22. 2% and 28. 7%, while the combined foam and bentonite slurry method required a ratio of 24. 3% to 31. 5%. Field application and construction feedback showed that the above improvement scheme effectively enhanced the flow plasticity of the muck, and significantly improved the shield thrust, cutterhead torque and tool wear. [ABSTRACT FROM AUTHOR]

Reasonable support force is crucial for the stability of the excavation face in sandy pebble tunnels. By utilizing the existing failure mode of the logarithmic spiral curve, this study combined the collapse arch model with the limit analysis method to establish a failure model for the excavation face in sandy pebble tunnels. A calculation method for the ultimate supporting force applicable to the excavation face of sandy pebble tunnels was also proposed. Then, the theoretical analysis presented in this paper was compared with numerical simulation and existing theories to determine the failure areas under different internal friction angles and cohesion values. Finally, the excavation face stability of a shield tunnel in Beijing was analyzed using theoretical analysis and numerical simulation methods. The results showed that the analytical solution proposed in this paper was in good agreement with the limit supporting force derived from existing research, with convenient and accurate calculations. The limit supporting force decreased nonlinearly with the increase of the internal friction angle, and was more sensitive to changes in the friction angle when the angle was small. The limit supporting force decreased approximately linearly with the increase in cohesion. When the burial depth was small, it had a more significant impact on the limit supporting force. When the C / D ratio exceeded 1. 0, the increase of the burial depth of the tunnel had no obvious effect on the limit supporting force, and the friction angle had a very significant effect on the failure area. With the increase of internal friction angle, the failure area decreased significantly. Cohesion had little impact on the failure area, i. e., the size of the energy dissipation surface remained nearly unchanged under different cohesion values. For the shield tunnel in Beijing, the calculation based on the limit analysis method optimized the collapse range and shape, making the failure mode more reasonable while increasing the failure range, achieving excellent engineering application results. [ABSTRACT FROM AUTHOR]

Efficient and accurate acquisition of slope shear strength parameters is the key to slope stability analysis and landslide prevention engineering design. This paper establishes a back analysis method based on uniform design, artificial neural network, and genetic algorithm. It can obtain the shear strength parameters of slopes based on information such as the radius and center coordinates of the slip surface obtained from on‐site investigations. This method has been applied to engineering practice. The research results indicate that the stability of the waste dump slope is most sensitive to the response of the internal friction angle of the loose body, followed by cohesion, and least sensitive to the response of the soil volume weight. This method can effectively reduce the number of network training samples and efficiently and quickly determine the initial weights of the BP (abbreviation for back‐propagation) neural network. This method can efficiently and quickly conduct back analysis to obtain the shear strength parameters of slopes. Using the obtained shear strength parameters for slope stability calculation, the most dangerous slip surface abscissa error, ordinate error, and slip surface radius error are only 3.59%, 0.95%, and 1.83%. It is recommended to promote the back analysis method of shear strength parameters in engineering practice in the future. [ABSTRACT FROM AUTHOR]

In this work, we investigate a dynamic internal dissipation mechanism in the context of cement-based materials by introducing a 1D-enhanced micromorphic beam model with a dynamic internal friction term. Here, we consider an inherent feature in concrete-like materials arising from the multi-scale structure, namely, microcracks. Thus, we assume that the internal dissipation of the energy depends on the overall relative sliding displacement of the opposite faces in the microcracks under the effects of an applied cyclic load whenever no significant phenomena related to damage occur at the macroscopic level. The dynamic friction term is based on a well-known model for dry friction in solids due to P. R. Dahl, where the friction force depends only on the sliding displacement and evolves in time, reproducing an elastoplastic behavior. The model proposed in this paper takes into account a mechanical energy interchange between both bending and shear distortion in the beam with the sliding occurring at the microcracks, a storage of mechanical energy because of the asperities inside the faces of the microcracks, and the dissipation of the energy that follows from the interaction between the bending and the microcracks. Numerical simulations of the kinematic descriptors and the dissipative cycles are also provided by using the Finite Element Method and the commercial software COMSOL Multiphysics®. [ABSTRACT FROM AUTHOR]

In order to study the shear mechanical properties of rock joint under different unloading stress paths, the RDS-200 rock joint shear test system was used to carry out direct shear tests on concrete joint specimens with five different morphologies under the CNL path and different unloading stress paths. The unloading stress paths include unloading normal load and maintaining constant shear load (UNLCSL), unloading normal load and unloading shear load (UNLUSL), unloading normal load and increasing shear load (UNLISL). The results show that the peak shear strength, cohesion, internal friction angle, pre-peak shear stiffness and residual shear strength of concrete joints under CNL path increases with the increasing JRC and normal stress. Under the UNLCSL path, under the same initial shear stress τ1, instability normal stress σi decreases with the increasing JRC, and normal stress unloading amount Δσn increases with the increasing JRC. Under the same JRC, σi increases with the increase of τ1, and Δσn decreases with the increasing τ1. Under the same JRC and σi, τi is significantly smaller under the UNLCSL path than the CNL path. Under the same JRC, the cohesion under the UNLCSL path is less than the CNL path, and the internal friction angle is higher than that the CNL path. Under the same JRC and σi, τi is the largest under the path of CNL and UNLISL, followed by the UNLCSL path, and τi under the UNLUSL path is the smallest. Compared with the CNL path, the variation range of the specimen internal friction angle is within 3% while the average decrease percentage of the specimen cohesion reaches 37.6% under the UNLCSL path, UNLISL, and UNLUSL. Therefore, it can be inferred that the decrease in cohesion caused by normal unloading is the main reason for the decrease in joint instability shear strength. After introducing the correction coefficient k of cohesion to modify the Mohr-Coulomb criterion, the maximum average relative error after correction is only 3.5%, which is significantly improved compared with the maximum average relative error of 56.9% before correction. The research conclusions can provide some reference for the accurate estimation of shear bearing capacity of rock joints under different unloading stress paths, which is of great significance to the stability evaluation and disaster prevention of rock mass engineering. [ABSTRACT FROM AUTHOR]

This study examines the influence of different grain size fractions of coal fly ash on the properties of clay-cement mortars used in flood levee construction. Dry aerodynamic separation and mesh sieving were used to obtain ultrafine, fine, and medium fractions of high-calcium and silica fly ash. The experimental results reveal that the rheological properties of fresh mortars are significantly influenced by these fractions. High-calcium fly ash mortars exhibit high reactivity and rapid increase in viscosity, with finer fractions showing the highest reactivity. Silica ashes show increased reactivity in the later stages of suspension hardening. Their spherical shape contributes to reducing internal friction during flow in initial technological operations. Furthermore, the compressive strength of hardened mortars improves as the particle size decreases for both ashes, resulting in a dense and uniform microstructure. The separation and fractionation of fly ashes contribute to the obtaining of fractions that influence the parameters of clay-cement suspension application on different scales. The results show the potential benefits of ash separation, which can bring advantages in terms of economic viability, engineering performance, and ecological sustainability. [ABSTRACT FROM AUTHOR]

The diverse and complex morphology of loess particles creates various contact patterns, impacting the mechanical properties of loess, and directly influencing the stability and safety of engineering structures in loess regions. In order to explore the effects of realistic loess particle morphology on mechanical behaviors, the discrete element method (DEM) and image processing techniques were employed to investigate both macro and micro mechanical properties, such as cohesion, internal friction angle, mechanical coordination number, and distribution of contact force. The results demonstrate that particle morphology greatly impacts the mechanical properties of loess samples. Samples with realistic particles exhibit higher peak stress, shear modulus, cohesion, internal friction angle and mechanical coordination number compared to those with spherical particles. Particle morphology has a significant effect on particle rotations and fabric anisotropy, while exerting only a minor influence on particle displacement. A comprehensive understanding of the relationship between the particle morphology and mechanical properties of loess samples contributes to enhancing the stability of engineering structures in loess areas. [ABSTRACT FROM AUTHOR]

Due to being lightweight, fine-grained sediments easily flow with water and thus amplify the destructive effect of debris flow hazards. In such hazards, water content and shear strength are key inter-controlled factors relating to the stability of fine-grained sediments and thus control the density, scale, and danger of debris flow hazards. Although the correlation between water content and sediment stability has been studied, there are still some issues to be solved: what is the changing trend of shear strength with increasing water content? What is the water content spatial distribution pattern of fine-grained sediments in debris flow? What is the role/impact of this pattern on debris flow hazards prevention? Therefore, the objective of this research is to show the spatial distribution pattern of water content and establish a correlation between the water content and the shear strength of fine-grained sediments to provide a scientific basis for debris flow hazard prevention. Taking the Beichuan debris flow for our study, with a length of 37.6 km, and a 341 km2 study area, the results show that (1) the average water content shows an increasing trend, from 9.9% in the upstream of the river (SP01–SP05) to 21.7% in the downstream of the river (SP13–SP15). (2) When unsaturated, the correlation between the water content and shear strength is determined by combining the cohesion, normal stress, and internal friction angle; when saturated, the water content is negatively correlated with shear strength. (3) Water content and shear strength are the key inter-controlled factors relating to the stability of fine-grained sediments, and the water content distribution pattern of this research indicates the key locations that require attention: locations with high water content in the downstream river or with high curvature, which is of some significance for debris flow hazard prevention. [ABSTRACT FROM AUTHOR]

To investigate the influence of varied mechanical parameters of coal mass on rock burst occurrence during deep roadway tunneling, the surrounding coal and rock mass of a deep roadway were taken as the research objects. A geometric model of roadway tunneling was developed using 3DEC numerical simulation software, and the failure characteristics of the coal mass in the roadway side were analyzed based on the rock burst mechanism and stress difference gradient theory for deep mining. The risk of rock burst during roadway tunneling was quantitatively assessed using the change rate of the stress difference gradient (Dgc), thereby elucidating the burst failure patterns of the deep roadway under the influence of varied mechanical parameters. The findings indicate that the coal mass in the roadway side zone is more prone to burst failure due to stress disturbances during deep excavation compared to the coal and rock mass in the roof and floor zones, and that the released kinetic energy and the risk of burst failure are positively correlated with the magnitude of the ground stress. The variation of the mechanical properties of coal mass has a significant effect on the rock burst risk during roadway tunneling. The variation of both internal friction angle and cohesion significantly affects rock burst, with cohesion exerting a greater influence. Conversely, the elastic modulus does not significantly impact the risk. The tendency of bursting in the coal mass is positively correlated with the coefficient of variation (COV) in cohesion and negatively correlated with the COV in internal friction angle. These research findings offer valuable insights for the quantitative assessment of rock burst risk during roadway tunneling. [ABSTRACT FROM AUTHOR]

Based on the Xiaolangdi North Bank Irrigation Area Project, this study combines numerical simulation and BP neural network methods to investigate the sensitivity of tunnel soil and its parameter inversion under continuous heavy rainfall. The research results indicate that changes in water-level and soil strength parameters have a significant impact on the deformation of tunnel surrounding rock. By comparing the sensitivity factors of different parameters, the main parameter sensitivities affecting the displacement of tunnel surrounding rock were determined to be water level, internal friction angle, and cohesion. The mechanical characteristics of the tunnel construction process were analyzed using finite difference method numerical analysis software FLAC3D, and the results were used as a sample dataset for inversion analysis. Through neural network inverse analysis based on orthogonal design method, the cohesion and internal friction angle of loess layer ④, loess layer ④-1, and loess layer ⑤ were determined, and the data of groundwater level elevation were obtained. Field applications proved the effectiveness and rationality of this method. [ABSTRACT FROM AUTHOR]

Herein, the interaction between hydrogen, microstructure, and mechanical properties in low-alloy high-strength marine steel was elucidated via microstructural characterization, internal friction analysis, hydrogen diffusion, and hydrogen-embrittlement sensitivity evaluation. Results indicated that the bainite structure of hot-rolled steel transformed into a coarse ferrite–pearlite structure after normalizing, and the hydrogen trap density decreased with decreasing grain boundary and dislocation densities. Therefore, the effective diffusion coefficient of hydrogen in the normalized steel plates increased with decreasing hydrogen permeation time. Owing to the coarsening of the microstructure, the normalized steel plates exhibited higher sensitivity to hydrogen embrittlement. The diffusion of a large amount of hydrogen into the steel considerably deteriorated its plasticity, resulting in a transition of its fracture mode from microvoid coalescence fracture to cleavage fracture. The internal friction behavior indicated that hydrogen in the microstructure generated a hydrogen-induced Snoek peak, as well as reduced the activation energy of Snoek–Kê–Köster and Kê peaks. Finally, the internal friction spectra revealed that the interaction between hydrogen and point defects, dislocations, grain boundaries, and precipitates was sequentially enhanced due to the increase in activation energy. [ABSTRACT FROM AUTHOR]

Acoustic holographic lenses (AHLs) show great potential as a straightforward, inexpensive, and reliable method of sound manipulation. These lenses store the phase and amplitude profile of the desired wavefront when illuminated by a single acoustic source to reconstruct ultrasound pressure fields, induce localized heating, and achieve temporal and spatial thermal effects in acousto-thermal materials like polymers. The ultrasonic energy is transmitted and focused by AHL from a transducer into a particular focal volume. It is then converted to heat by internal friction in the polymer chains, causing the temperature of the polymer to rise at the focus locations while having little to no effect elsewhere. This one-of-a-kind capability is made possible by the development of AHLs to make use of the translation of attenuated pressure fields into programmable heat patterns. However, the impact of acousto-thermal dynamics on the generation of AHLs is largely unexplored. We use a machine learning-assisted single inverse problem approach for rapid and efficient AHLs' design to generate thermal patterns. The process involves the conversion of thermal information into a holographic representation through the utilization of two latent functions: pressure phase and amplitude. Experimental verification is performed for pressure and thermal measurements. The volumetric acousto-thermal analyses of experimental samples are performed to offer a knowledge of the obtained pattern dynamics, as well as the applicability of holographic thermal mapping for precise volumetric temperature control. Finally, the proposed framework aims to provide a solid foundation for volumetric analysis of acousto-thermal patterns within thick samples and for assessing thermal changes with outer surface measurements. [ABSTRACT FROM AUTHOR]

Loess is strongly sensitive to water, and its properties are substantially affected by weathering and other factors. Loess landslides, which are widely distributed in Ili, are closely related to seasonal freeze-thaw effects. In this study, multiple freeze-thaw cycle tests were conducted on loess samples with different moisture contents from the Ili region, and triaxial shear tests were conducted to study mechanical characteristics of the loess. Variations in the microstructure of the loess samples were analysed using scanning electron microscopy images to reveal the underlying mechanisms. The results showed that the freeze-thaw cycles significantly influence failure mode of the stress-strain curve of loess samples with a lower moisture content of 10%, which transitioned from strain softening to strain hardening with six cycles as the turning point, whereas the stress-strain curve transitioned from strong to weak hardening for the loess samples with higher moisture content of 18%. As the number of freeze-thaw cycles increased, failure strength and shear strength parameters of loess gradually decreased, and tended to stabilize after the 10th cycle. In addition, strength parameters deterioration is most significant after the first cycle, and the degree of cohesion deterioration was much greater than that of internal friction angle. Cohesion and internal friction angle showed attenuation exponential function and polynomial function relationship, respectively, with the number of freeze-thaw cycles, and their fitting parameters underwent a sudden change with increasing moisture content, with 14% as the turning point. Microscopic SEM revealed that the number of overhead pores increased, and point-to-point contact between particles increased after freeze-thaw, which was consistent with increase in of loess porosity. This revealed the fundamental reason for the significant deterioration in loess strength caused by freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

Rocks exhibit various mechanical properties under different stress conditions, with changes during unloading having significant implications for geological engineering safety. This study carried out triaxial loading and unloading mechanical tests on sandy slate to investigate its mechanical properties, deformation characteristics, and failure mechanisms at different initial stress levels and stress paths. The results showed that during the unloading process, the deformation modulus (E) of the sandy slate decreased, and the Poisson's ratio (μ) gradually increased. This indicates that significant volume expansion of the rock is the dominant factor in its deformation and failure. The exponential function can be used to describe the evolution of E and μ with confining pressure during unloading. The damage stress of the rock under unloading conditions was lower than that under loading conditions, suggesting that unloading led to an earlier onset of volumetric expansion in the sandy slate. Under conditions where the initial axial stress level approached the damage stress, the mechanical properties were most significantly affected by unloading. Compared to loading conditions, when the initial axial stress level was at 70% of the peak strength, the cohesion (c) decreased by 15.77 to 29.37%, while the internal friction angle (φ) increased by 1.88 to 5.14%. The rock's failure process can be divided into four stages based on the development of microcracks. Unloading during the stages of microcrack initiation and propagation can lead to tensile cracks of varying degrees, resulting in different mechanical properties and failure characteristics under loading and unloading conditions. [ABSTRACT FROM AUTHOR]

Shear strength (SS) parameters are essential for understanding the mechanical behavior of materials, particularly in geotechnical engineering and rock mechanics. This study proposes a novel hierarchical ensemble model (HEM) to predict SS parameters: cohesion (C ) and angle of internal friction (φ ). The HEM addresses the limitations of traditional machine learning models. Its performance was validated using leave-one-out cross-validation (LOOCV) and out-of-bag (OOB) evaluation methods. The model's accuracy was assessed with R-squared correlation (R2), absolute average relative error percentage (AAREP), Taylor diagrams, and quantile–quantile plots. The computational results demonstrated that the proposed HEM outperforms previous studies using the same database. The model predicted φ and C with R2 values of 0.93 and 0.979, respectively. The AAREP values were 1.96% for φ and 4.7% for C . These results indicate that the HEM significantly improves the prediction quality of φ and C , and exhibits strong generalization capability. Sensitivity analysis revealed that σ_3maxσ3max (maximum principal stress) had the greatest impact on modeling both φ and C . According to uncertainty analysis, the LOOCV and OOB had the widest uncertainty bands for the φ and C parameters, respectively. [ABSTRACT FROM AUTHOR]

Drawing from the engineering context of a shallow-buried, biased-load, permeable ribbed double-arch tunnel, the strength reduction method was employed to determine the failure pattern of the surrounding rock at the tunnel's ultimate excavation state. According to the failure characteristics of surrounding rock and the basis of basic assumptions, a fractured sliding surface was hypothesized, and a structural load calculation model for the surrounding rock pressure in the permeable ribbed double-arch tunnel was derived. This model was compared and validated against the results obtained from the stratum structure model. An analysis of the sensitivity of the surrounding rock pressure was conducted. The findings indicated that the tunnel was subjected to asymmetric biased loads, with the vertical load on the side with large buried depth chamber being significantly greater than that on the side with small buried depth chamber. The horizontal load on the right sidewall of the side with large buried depth chamber was significantly greater than the horizontal load on the surface of the left and right lining segments above the central partition wall. The horizontal lateral pressure coefficient was influenced by the slope's biased angle and the internal friction angle of the surrounding rock's sliding surface, with the latter having a more substantial effect. The surrounding rock pressure was closely related to the horizontal lateral pressure coefficient and was influenced by the rock density, the slope's biased angle, and the internal friction angle of the sliding surface. The sensitivity of surrounding rock pressure was significantly impacted by the slope's biased angle and the internal friction angle. [ABSTRACT FROM AUTHOR]

Rough surfaces in microchannels effectively enhance liquid mixing, thermal performance, and chemical reactions in electrically actuated microfluidic devices. Rotation of the microchannel with surface roughness intensifies this enhancement. We investigate the combined effects of electromagnetohydrodynamics and surface roughness on transient rotating flow in microchannels. We present a mathematical model considering the variable zeta potential, heat transfer characteristics, and entropy generation within the microchannel. We obtain analytical solutions using the separation of variables method and Fourier series expansion. The surface roughness of the microchannel, when combined with rotation, impacts the temperature enhancement. Higher rotation rates result in the formation of multiple vortices. The secondary flow pushes the primary velocity toward the boundary layer, which affects the flow pattern. Surface roughness and electroosmotic flow significantly affect secondary flow, resulting in complex flow patterns and reversals. The interaction between centrifugal and viscous forces results in maximum velocities at the boundary layers. Higher roughness and electromagnetic effects enhance temperature by intensifying fluid-solid friction and joule heating. Surface roughness causes an increase in wall shear stress and friction factor, resulting in a higher Poiseuille number. Moreover, surface roughness increases entropy production by enhancing fluid mixing and internal friction despite improved heat transfer. Higher rotation also elevates entropy generation due to additional vortices induced by secondary flow. [ABSTRACT FROM AUTHOR]