The use of iron tailing powder (ITP) and granulated blast-furnace slag (GBFS) offers a feasible route for preparing low-cement mortar while recycling industrial by-products. In this study, seven cement mortar mixtures were designed to investigate the influence of the ITP–GBFS ratio on mechanical properties, microstructure, hydration products, and chloride ion penetration resistance. The mixtures included plain cement mortar (A0), mortar with 50% ITP (A1), mortar with 50% GBFS (A2), and four composite mixtures (A3–A6) in which ITP and GBFS jointly replaced 50% of cement at different ratios. The results showed that the mixture containing 20% ITP and 30% GBFS (A4) exhibited the best overall performance among the composite mixtures. At 28 d, A4 reached a compressive strength of 51.3 MPa and a flexural strength of 11.0 MPa, exceeding those of the plain cement control. SEM and XRD analyses suggested that the optimized ITP–GBFS combination promoted the formation of poorly crystalline hydration products, such as C–S–H/C–A–S–H gels, and refined the pore structure, resulting in a denser hardened matrix. The rapid chloride migration test showed that the chloride migration coefficient of A4 was 15.47 × 10−12 m2/s, only slightly higher than that of A0, indicating that the optimized composite binder maintained chloride penetration resistance close to that of plain cement mortar while replacing 50% of cement. The results indicate that a properly proportioned ITP–GBFS binder can maintain acceptable strength and chloride resistance while reducing cement consumption.

ABSTRACT This study investigates the dynamic stability of frozen soil slopes subjected to strong disturbances such as blasting. Dynamic compression tests were conducted on saturated frozen clay specimens using a split Hopkinson pressure bar system. The effects of strain rate (100–700 s−1), temperature (−15°C, −23°C, and −30°C), and pore ratio (0.30, 0.24, and 0.18) on the mechanical behavior were systematically examined. The propagation of stress waves and the dynamic stress–strain responses were analyzed. Results show that as the strain rate increases, the arrival times of the incident, reflected, and transmitted wave peaks advance, and the time to reach peak energy, stress, and strain decreases. This trend is consistent across all tested temperatures and pore ratios. Both lower temperatures and higher pore ratios lead to increased specimen strength and a marked shortening of the plastic plateau stage in the stress–strain curves. Based on the experimental results and the effective stress principle for saturated soils, a damage-enhanced constitutive model was developed within the Zhu-Wang-Tang constitutive framework by incorporating a wave-impedance term. This term links microstructural changes (ice content and cementation) to macroscopic strength, effectively characterizing the coupled effects of strain rate, temperature, and pore ratio. The model predictions show good agreement with the experimental data, providing a theoretical basis for the dynamic analysis of frozen soil engineering.

The dynamic interaction between blast-induced stress waves and propagating cracks influences the fracture behavior and performance of materials under dynamic loading. This paper experimentally investigates how stress wave characteristics affect the propagation path, velocity, and dynamic stress intensity factors of moving cracks in polymethyl methacrylate (PMMA). Two typical stress wave loading scenarios are designed: reflected tensile waves from the upper boundary in single-borehole blasting and obliquely incident compressive waves from delayed double-borehole blasting. A dynamic caustics optical system combined with high-speed photography is employed to capture the entire crack initiation, propagation, and deflection process in real time. The results indicate that stress wave characteristics govern crack behavior through a dual-parameter coupling mechanism of energy and direction. Tensile waves increase the mode I dynamic stress intensity factor KId, promoting crack propagation, whereas compressive waves decrease KId, inhibiting crack propagation. The incident direction and wave type jointly determine the sign and magnitude of the mode II dynamic stress intensity factor KIId, thereby controlling the crack deflection direction. The findings establish a quantitative correlation between stress wave parameters and crack tip stress field evolution, providing experimental insights into dynamic fracture characterization of materials under complex transient loading conditions.

Coal gangue (CG) ranks among China's most significant industrial solid by-products. In response to China's carbon neutrality commitments and the growing emphasis on resource recycling, finding effective ways to valorize CG has emerged as a pressing concern. Based on the mineral composition and chemical composition characteristics of CG, this study systematically investigated the enhancement effects of three alkali activators (Na2SiO3, NaOH, and Ca(OH)(2)) on the cementitious properties of CG. Through different dosage and compressive strength tests, the efficiency ranking of the three activators was determined as follows: Na2SiO3 > Ca(OH)(2) > NaOH. A 10% Na2SiO3 dosage combined with 28-day curing was identified as the optimal condition for achieving sufficient reaction and structural densification. Under these conditions, the compressive strength of CG cementitious material reached 6.4 MPa, representing an increase of 190.9% compared to the blank group (2.2 MPa), significantly superior to Ca(OH)(2) (69.55%) and NaOH (62.27%). X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analyses revealed that alkali activators function primarily by disrupting the crystalline framework of CG, promoting the cross-linking polymerization of silicon-aluminum monomers to generate dense cementitious products, thereby improving material performance. The Na2SiO3 is attributed to its "dual activation effect", providing OH- to create an alkaline environment while supplying reactive silicate ions (SiO32-) to accelerate N-A-S-H gel and C-A-S-H gel formation. These findings offer guidance for optimizing CG-based cementitious formulations for formula optimization and large-scale utilization of CG cementitious materials.

Over the years, the directional fracture control blasting technology using slotted charges has been widely applied in the formation control around rock tunnels. This article employs CT scanning technology and numerical simulation methods to investigate the influence of bedding angle on the blasting fracture effect in layered rock masses under different bedding strengths. The results indicate that in layered rock masses with strong bedding bond strength, the slotted charge still exhibits good directional fracture effects. The angle of strong bedding significantly affects the propagation of the explosive stress wave from the slotted charge, thereby influencing the overall damage of the specimen. Changes in the angle of the strong bedding plane have a certain impact on the expansion trajectory of the main blasting crack. As the inclination angle of the weak bedding plane increases, the influence of the weak bedding plane on the crack propagation behavior gradually increases.

Accurate monitoring of ocean tides is essential for understanding coastal ocean dynamics and ensuring marine infrastructure safety. We propose a muon-imaging based approach for passive tidal monitoring and deploy an upward-looking detector inside the Jiaozhou Bay subsea tunnel. By combining continuous muon flux measurements with Geant4 simulations, we quantify the modulation of muon flux induced by tidal variations in the overlying water column. The observed muon flux exhibits a clear periodic oscillation with a dominant period of -12.4 h, consistent with the M2 semidiurnal tide, and a relative amplitude of -3%. Cross-correlation analysis reveals a phase lag of approximately - 154.6 degrees between the muon flux and tidal height, in agreement with the expected modulation by water-column density length. These results provide the first demonstration that muon imaging can achieve long-term, passive tidal monitoring in a subsea tunnel environment, offering a new observational tool for coastal and ocean dynamic studies.

Mineral carbonation of mine tailings represents a promising pathway for large-scale CO2 utilization, yet diffusion limitations within cementitious matrices often hinder capture efficiency. This study develops a hierarchical porous paste backfill utilizing molybdenum tailings and sodium dodecyl sulfate (SDS) to optimize the trade-off between gas permeability and adsorption capacity. We investigated the regulatory mechanism of pore architecture on CO2 uptake through multiscale characterization (NMR, BET, XRD) and kinetic modeling. The results demonstrate that an optimal SDS dosage of 0.2 wt% generates a balanced micro-meso-macro pore network, increasing the BET surface area to 60.857 m2/g and enhancing gas permeability from 0.035 mD to 0.368 mD. This optimized architecture facilitated a 53% increase in CO2 capture capacity (reaching 3.64%), dominated by coupled chemisorption and mineralization kinetics. Crucially, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses reveal that in-situ formed CaCO3 provides secondary pore filling, allowing the carbonated material to maintain a robust 28-day compressive strength of 2.8 MPa. Furthermore, life cycle assessment (LCA) indicates that porosity optimization shifts the system from a carbon source (85.8 kg) to a carbon sink (-5.36 kg). These findings provide mechanistic insights into designing carbon-negative backfill materials, validating the potential of pore engineering to enhance CO2 utilization in the mining sector.

Rapid and reliable prediction of spatiotemporal mechanical responses is essential for design iteration and safety assessment in geotechnical systems. For rockfill dams, the nonlinear and path-dependent evolution of stress and deformation during staged construction and reservoir impoundment makes finite element analysis (FEA) computationally expensive, limiting time-critical assessment and fast design exploration. Existing data-driven surrogates often target extrema or single-stage responses and struggle to capture the continuous evolution of mechanical fields throughout construction. Although recent studies improve field prediction through monitoring data assimilation or physics-informed loss functions, such approaches are often infeasible at the dam design stage, when monitoring data are unavailable, and may generalize poorly to unseen conditions. This study develops a pretrained, physics-guided framework for predicting the continuous evolution of stress and deformation fields in rockfill dams. A patch-token representation is introduced to capture temporal interactions and crossfield correlations across construction stages. The framework adopts a generative surrogate learning scheme with a decoupled strategy that separates global response from localized spatial variations. Material properties, geometric configurations, and boundary conditions are explicitly encoded to maintain physically consistent predictions. Evaluations on parametric FEA datasets show that the framework accurately reproduces both global response trends and spatial patterns during long-term autoregressive prediction. On unseen cases, peak mechanical responses achieve high coefficients of determination, while generated field distributions maintain structural similarity indices above 0.98 across construction stages. Engineering case studies further demonstrate speedups of approximately three orders of magnitude over conventional FEA, reducing simulation time from hours to seconds while preserving high-fidelity predictions.

Cracks in concrete structures are key indicators of deterioration, yet reliable recognition across scales, from mmscale hairline cracks to cm-scale fractures, remains difficult due to pronounced cross-scale appearance variation and topological complexity. This study presents an adaptive deep-learning framework that unifies crack localization, contour segmentation, and dimensional measurement. For efficient localization, deformable convolutions are integrated into YOLOv8 to form DCNv4-YOLOv8, improving sensitivity to slender and irregular cracks. For contour delineation, a CM-DeepLabv3 + network is proposed by embedding a multi-scale magnification attention module (MSA) and a continuity-aware module (CAM), enabling instance-adaptive scale emphasis and connectivity-preserving refinement. The resulting masks are fused with RGB-D data through 2D-to-3D backprojection, and the reconstructed crack point clouds are subsequently refined by point densification and statistical outlier removal. Crack length and aperture are then quantified from the extracted crack skeleton and its orthogonal cross sections. Experiments show that DCNv4-YOLOv8 improves mAP50-95 by 5.4 % over the YOLOv8 baseline, while CM-DeepLabv3 + increases mIoU from 72.6 % to 80.5 %. Field and laboratory specimen validations confirm millimeter-level aperture estimation and centimeter-level length measurement accuracy, demonstrating robust performance across diverse crack scales and scenarios.

The coupled system of waste dump and tailings pond has become increasingly prevalent in mineral resource development in China, but its structural stability poses significant risks to both mining safety and ecological sustainability. This study proposes a failure mode analysis framework that integrates traditional geotechnical testing with digital image analysis techniques to investigate the deformation and failure mechanisms of such coupled systems. Using the joint construction project of a molybdenum mine in Inner Mongolia as a case study, the main risk factors arising from the interaction between the dump and tailings pond were qualitatively identified. Particle gradation and shear strength parameters of the dump, tailings, and foundation soils were determined through laboratory geotechnical tests. Furthermore, a bottom-friction physical model test was conducted to simulate failure evolution under varying boundary conditions. To enhance predictive capacity, displacement field data and test imagery were processed using digital image correlation (MatchID 2D) to identify critical deformation patterns and potential failure zones. This digital image-assisted approach improves the resolution and interpretability of physical tests, enabling earlier warning and more informed design decisions. The study provides an experimental framework for risk assessment, monitoring, and optimization of coupled waste dump–tailings pond systems.

Municipal solid waste incineration fly ash (MSWI-FA) is an urgently treatable hazardous waste in China. High-temperature melting is a promising resource utilization technology for global solid waste. This study examines physicochemical properties of grate furnace incineration fly ash from northern and southern China, finding Cd, Pb, and Zn leaching toxicity exceeds national standards by 9.14, 8.59, and 1.09 times for northern samples, and 17.58, 7.13, and 1.25 times for southern samples, respectively. Clinker ignition loss during melting reaches approximately 40

The permeability of tailings is a key factor governing the drainage performance and long-term stability of tailings dams. The permeability coefficient evolves under the combined influences of stress state, density, and structural characteristics. However, its evolution pattern under shear stress remains insufficiently understood, which necessitates a systematic investigation into the underlying microstructural mechanisms. This study integrates triaxial shear-seepage coupling tests, X-ray computed tomography (X-CT), particle size distribution (PSD) testing, and pore network analysis to investigate permeability evolution mechanism in loose fine-grained tailings. The results show that permeability decreases by 6.159-9.677 times due to the combined effects of confining pressure and shear stress. Microstructural analyses indicate that permeability coefficient evolution is governed by confinement-induced particle compaction, shear-driven particle migration, and particle breakage. PSD results further confirm grading refinement after shearing, indicating the generation of additional fine particles and local pore filling. Pore-scale seepage simulations, coupling Avizo-based reconstructions with COMSOL Multiphysics, show that with increasing confining pressure and shear stress, flow transitions from concentrated high-velocity channels to a more uniformly distributed low-velocity regime. The numerically obtained permeability coefficients are in close agreement with the experimental measurements. On this basis, a permeability evolution model is established within a Kozeny-Carman framework using void ratio and generalized shear strain as governing variables. The proposed formulation provides improved predictive capability relative to void-ratio-only relationships while maintaining physically consistent limiting behavior and practical usability for engineering applications.

Inadequate freezing is an inevitable intermediate state in freeze–thaw cycles and an important factor affecting the seismic behavior of moraine-soil slopes along Sichuan–Tibet railway. A self-made incubator was employed to complete the inadequate freezing process of the moraine-soil slope, and serial shaking table tests on moraine-soil slopes were conducted using existing shaking table devices. A speckle analysis system and accelerometers were adopted to track the slope displacement and acceleration response, and the slope seismic behavior was revealed through the evolution characteristics of acceleration, displacement and frequency spectrum. These results show that: (1) Under inadequate freezing and earthquakes, the main change of slope dynamic characteristics is a decrease in natural frequency and an increase in damping ratio. (2) Dynamic failure process of the moraine-soil slope after inadequate freezing could be summarized into four stages: elastic deformation stage with peak acceleration less than 0.4g, brittle failure stage with peak acceleration from 0.4g to 0.8g, plastic failure stage with peak acceleration from 0.8g to 1.1g, and failure slip stage with peak acceleration greater than 1.1g. (3) Seismic behaviors of the moraine-soil slope after inadequate freezing exhibit significant frequency effects, amplitude effects, slope-surface effects and elevation effects. (4) Low temperature freezing amplifies the slope dynamic response, and the larger the freezing coefficient, the stronger the dynamic response. (5) Under inadequate freezing and earthquakes, the failure pattern of a moraine-soil slope is an overall landslide along the slip surface formed by connecting cracks, which is similar to that of a rock slope with weak slip surfaces. These results have important reference value for further researches of slope seismic behaviors along Sichuan–Tibet railway.

There is a huge risk of dam failure during the operation of tailings ponds. Domestic and foreign scholars have conducted extensive research on the assessment and prevention of dam failure risks during the operation of tailings ponds, but there are still many shortcomings. On the basis of exploring the key issues of dam failure risk assessment during the operation of tailings dams, this paper establishes a comprehensive evaluation index system for dam failure risk during the operation of tailings dams based on ten principles including scientificity, systematicity, and operability. By exploring the use of the change statistical mapping method, we can determine the weight of indicators. A risk assessment model was constructed using the fuzzy comprehensive evaluation method; compared to the traditional fuzzy comprehensive evaluation method, this model determines weights in a more extensive and scientific manner. The scientific and effective nature of the model was verified through case analysis of the Shouyun Iron Mine and Shangyu Tailings Reservoir in Beijing. Finally, in response to the risk of dam failure during the operation of tailings ponds, scientific prevention and control measures were proposed from four aspects: personnel risk prevention and control, inherent risk prevention and control of tailings ponds, environmental factor risk prevention and control, and management risk prevention and control.

To investigate the interaction between blasting crack and circular hole with various offset distances in PMMA, this study examined the propagation and arrest mechanisms of blasting crack utilizing a dynamic caustics experimental system. When the offset distance (d) >= 8 mm, the circular hole had a negligible effect on crack propagation. When d = 6 mm, the velocity and mode I stress intensity factor of the crack propagating near the circular hole were significantly reduced. The circular hole exerted a notable hindering effect on the blasting crack, however, it did not completely arrest the crack propagation. The crack initially approaches and subsequently moves away from the circular hole. When d <= 4 mm, the crack stoped at the circular hole.

Balancing high fluidity and stability is a critical challenge in deep-shaft cemented paste backfill (CPB) with high-concentration tailings. This study investigates the synergistic regulation mechanism of a combined admixture system comprising hydroxypropyl methylcellulose (HPMC) thickener and polycarboxylate (PCE) or Melamine-Formaldehyde Resin (MFR) superplasticizers on CPB rheology, mechanical strength, and microstructure. Results indicate that HPMC significantly enhanced anti-segregation performance via intermolecular bridging, substantially increasing yield stress and plastic viscosity. Upon PCE introduction, the steric hindrance provided by its side chains effectively disrupted HPMC-induced flocs and released entrapped water. Consequently, yield stress and plastic viscosity were reduced by up to 22.1% and 64.3%, respectively, with PCE exhibiting markedly superior viscosity-reducing efficiency compared to MFR. Mechanical testing revealed that PCE co-addition did not compromise early-age strength but enhanced 3, 7, and 28-day unconfined compressive strength (UCS) by refining pore structures and promoting the uniform distribution of hydration products. Microstructural analysis unveiled a competitive adsorption mechanism: preferential PCE adsorption dispersed particle agglomerates, while non-adsorbed HPMC formed a viscoelastic network within the pore solution, constructing a stable "dispersion-suspension" microstructure. This work provides a theoretical basis for optimizing high-performance backfill formulations.

Red mud (abbreviated as RM) is a solid waste formed during the alumina refining process from bauxite. Every year, over 200 million tons of RM are discharged worldwide. China is a large producer of alumina; the entire amount of RM of China in storage exceeds 1 billion tons because there is no technology for large-scale treatment. Extensive studies on the sustainable utilization of RM have been conducted globally in recent decades. Thus, a detailed review is provided here. According to relevant data from institutions such as the International Aluminum Association, the critical situation of production and utilization of RM from 2011 to 2022 for the world and China are analyzed. This paper uses a comprehensive literature database to classify and statistically analyze RM related publications from 2011 to 2022. The results show that research on the comprehensive utilization of RM is mainly focused on three fields of metallurgy, construction, and environment. In these fields, the main issues of not achieving large-scale production of RM in China are discussed. The results indicate that unclear responsibilities, high technical costs, lack of policies and standards, and insufficient cross-disciplinary collaboration are the main reasons. Suggestions of the utilization and development of RM have been proposed.

The evolution characteristics of a stress field under blast loads are key issues in the study of dynamic rock fragmentation mechanism. This paper focuses on the rapid changes and difficulties in quantitative characterization of blast stress fields, and establishes an integrated experimental system that combines dynamic photoelasticity with digital image correlation for blast load tests. This system includes a blast load simulation device, a dynamic photoelasticity device, a digital image correlation monitoring device, and a data acquisition and analysis setup. It enables the high-precision synchronous acquisition of both structural internal stress fields and surface deformation fields under blast loads. On this basis, a method for calculating the principal stress at any point under blast loads is proposed, which is used to accurately measure and analyze the spatio-temporal distribution and deformation evolution process of the stress field under blast loads. The system was applied to quantitatively investigate the distribution characteristics of stress and deformation fields under single-hole explosive blasting. The effectiveness of this calculation method for studying the dynamic response of materials under blast loads has been validated. This comprehensive experimental system and methodology provide, to our knowledge, new experimental tools and analytical techniques for understanding the high strain rate behavior of materials. It has important research and application value for material performance evaluation, structural design, and safety protection.

The presence of lenses such as tailings slurry, frozen soil, and saturated zones disrupts the continuity of tailings dams and their normal seepage patterns, elevating the seepage line of the dam body and significantly impacting local stability. This study, to investigate how lenses affect the stability and failure mechanisms of tailings dams, employs numerical simulation and physical models and constructs a model of the tailings dam, incorporating tailings clay lens and void lens, to investigate variations in hydraulic gradients, seepage velocities, seepage flow, pore water pressure, and the patterns of seepage failure. This research reveals that the tailings clay lens within the dam body increases the hydraulic gradient in its vicinity due to its low permeability and raises the phreatic line. As the tailings clay lens approaches the dam body, the phreatic line tends to escape along the upper part of the lens towards the dam surface. In addition, the void lens could lead to a more pronounced seepage gradient along its path on the dam surface, with a liquefaction beneath it. As the void lens nears the toe of the slope, the dam failure mode transitions from a step-like progressive failure to an arch-shaped settlement failure along the void lens.

To address the concerns regarding a disused tailings pond, a closure engineering design and dam flood control safety evaluation were conducted. The proposed reservoir closure treatment methods, including adding flood drainage system (spillway), plugging the existing overflow tower and drainage pipe, were developed in combination with the construction conditions of the reservoir area. Then, hydrological calculations and flood routing for the tailings pond were performed, and the flood control safety of the tailings pond was evaluated. The results of the study indicate that after the designed closed pond treatment method for the tailings pond is adopted, a 1000-year design flood would result in a flood elevation of 0.7 m, a minimum safety super-elevation of 2.0 m, and a minimum dry beach of approximately 130 m. These findings are in compliance with the relevant regulations and requirements of the specifications, and thus ensure the flood control safety of the tailings pond.