Dongwei Li

To address the complex mechanical properties of coastal clay encountered during artificial ground freezing construction in coastal regions, this study investigates coastal clay by conducting mechanical tests under various freezing temperatures and confining pressures. The variations in peak strength, elastic modulus, and shear strength parameters of the frozen coastal clay were systematically analyzed. The results indicate that the peak strength and elastic modulus of the coastal clay exhibit a clear upward trend with approximately linear increases in confining pressure and temperature. A damage constitutive model for frozen soil was established, accounting for the coupled effects of temperature and confining pressure. Furthermore, a Physics-Informed Neural Network (PINN), incorporating the constitutive equations as physical constraints, was introduced to achieve the inversion and prediction of model parameters. The results demonstrate that the PINN model exhibits excellent predictive accuracy, with the coefficient of determination (R²) reaching 0.8513 under uniaxial compression and 0.9689 under triaxial compression. Compared with traditional empirical models, the PINN model reduces the prediction error of the elastic modulus to 8.96% (at 0 MPa) and 4.79% (at 0.8 MPa), demonstrating superior generalization capability. This study provides a reliable theoretical basis and parameter guidance for frozen soil construction in coastal regions.

To address the poor resistance of recycled aggregate concrete (RAC) to chloride ion penetration and freeze–thaw deterioration in cold coastal regions, this study introduces basalt fibers (BFs) as a reinforcement to improve its durability and structural integrity. Rapid freeze–thaw and electric flux tests, combined with scanning electron microscopy (SEM), were employed to systematically evaluate the effects of fiber volume fraction and length configuration on the frost resistance and chloride impermeability of basalt fiber-reinforced RAC (BFRAC). The experimental results demonstrated that the incorporation of basalt fibers markedly enhanced the coupled durability of RAC, with the mixture containing 0.15% fiber volume and a balanced hybrid of short (12 mm) and long (18 mm) fibers achieving the most favorable performance. This mixture effectively reduced mass loss and strength degradation under repeated freeze–thaw cycles while substantially lowering chloride ion penetration compared with plain RAC. Microstructural observations revealed that the hybrid fiber system formed a multi-scale three-dimensional network, in which short fibers restrained microcrack initiation and long fibers bridged macrocracks, jointly refining the pore structure and improving the interfacial bonding between recycled aggregates and the cement matrix. This synergistic mechanism enhanced matrix compactness and obstructed chloride transport, leading to a more stable and durable composite. The findings not only establish an optimal basalt fiber design for improving RAC durability but also elucidate the fundamental mechanism underlying hybrid fiber synergy. These insights provide valuable theoretical guidance and practical strategies for developing sustainable, high-performance concrete suitable for long-term service in cold-region coastal infrastructures.

To enhance the mechanical properties and low-carbon characteristics of industrial solid waste concrete, this paper proposes a synergistic modification strategy using nano-SiO₂ and sodium silicate. The nano-SiO₂ sol and sodium silicate activator were prepared using magnetic heating and stirring technology, and a quadratic regression model (R² = 0.9575, p < 0.0001) for compressive strength with three factors and three levels was established using the response surface method (RSM-CCD). The modification mechanism was verified through optimization of the mix ratio using a desirability function, along with microscopic characterization via SEM and XRD. The results indicate the following: (1) the content of nano-SiO₂ (2.4%) contributed the most to the compressive strength of the concrete, and its interaction with sodium silicate (2.1%) significantly promoted the formation of C-S-H gel; (2) the optimized fly ash substitution rate (21.7%) can achieve a 28-day compressive strength of 34.8 MPa, with the model prediction error controlled within 5%; (3) microscopic analysis showed that the synergistic effect of multiple components lowered the volume porosity of the cementitious phase, forming a densified network structure. The multi-factor synergistic optimization approach for nano-SiO₂-modified alkali-activated concrete (NS-AAC) proposed in this study offers a reference for multi-objective mix design optimization of industrial waste-based concrete.

In the context of intelligent construction and building industrialization, assembly buildings face many challenges in quality management due to their special design and construction characteristics. Therefore, a comprehensive method for evaluating the quality risk of the whole process of assembly building is proposed. This method is based on game-theoretic combinatorial empowerment and three-dimensional cloud modeling. By identifying the key risk factors, analyzing and classifying the quality risks that may exist in the whole process of the assembly building project, using the game theory combination assignment method to determine its comprehensive weight, establishing the game-theoretic-combinatorial-assignment three-dimensional cloud model, calculating and comparing the distance between the evaluation cloud and the standard cloud, and determining the risk level of the indexes, thereby realizing the comprehensive assessment of the quality risk. Example validation shows that the method yields a risk level of II for the whole project, which is more consistent with the actual situation, and by comparing with the two-dimensional cloud model, it further verifies the effectiveness and advantages of the three-dimensional cloud model in identifying the high hidden risks, and provides a new idea and method for the quality management of the whole process of the assembled building.

This study aims to refine the ratio of alkali-activated steel slag (SS) to granulated blast furnace slag (GBFS)–cement-based grouting materials, with the dual objectives of cost reduction and performance enhancement. By employing single-factor experiments and response surface methodology (RSM), we have pinpointed the critical factors that influence the slurry’s performance and developed a regression model to assess the impact of these factors and their interplay. Our findings indicate that the compressive strength initially increases with higher SS content but subsequently declines. Additionally, an increase in alkali content and activator modulus is beneficial for strength improvement. However, beyond an alkali content of 8%, the 28-day strength is observed to decrease. Through meticulous model analysis, we have determined the optimal ratio to be 7.07% SS content, 7.82% alkali content, and an activator modulus of 1.8. The material’s performance at this ratio satisfies construction specifications. This research not only offers a cost-effective and high-performance grouting solution for geotechnical applications but also pioneers a novel approach to the resourceful utilization of solid waste materials, such as SS.

In order to study the changes in the mechanical properties of road subgrade in cold areas after the freezing and thawing of highways in cold areas, indoor mechanical tests were carried out to investigate the effects of the number of freeze–thaw cycles, freezing temperature, water content, and circumferential pressure on the mechanical properties of road subgrade soil in cold areas after thawing. The mechanical properties of road subgrade soil in cold areas after thawing were measured under different conditions. The test results show that, within the study range: (1) After 7 freeze–thaw cycles, the destructive stress of the subgrade soil decreased from 321.7 kPa to 289.9 kPa, a decrease of 9.9%, and the elastic modulus decayed by 19.9%. (2) When the freezing temperature was reduced from −5 °C to −15 °C, the destructive stress of the subgrade soil decreased from 303.9 kPa to 290.1 kPa, a decrease of 13.8 kPa, approximately 4.5%, and the decrease in modulus of elasticity was about 1.6%. (3) The water content increased from 6% to 12%, and the destructive stress decreased from 405.43 kPa to 288.4 kPa, a decrease of 29.1%, and the modulus of elasticity decreased approximately linearly, with an attenuation of 50.4%. (4) The peripheral pressure increased from 50 kPa to 150 kPa, and the destructive stress increased from 194.7 kPa to 367.7 kPa, a growth of 88.8%, and its modulus of elasticity increased with the increase in peripheral pressure, an increase of 154.1%. The results of this research can provide a reference for highway and engineering construction in the western silt–soil distribution area.

In response to the challenges posed by rapid development, the wide-ranging disaster impact, and the untimely warning of debris flow resulting from tailing dam failure, it is of great significance to study the mechanism of dam failure as well as the evolution law and affected area of debris flow for effective disaster prediction and risk assessment. We developed a 1:150 physical model for testing tailing dam failure and combined it with RAMMS (V1.7.0) debris flow software to investigate the mechanisms of tailing dam failure and the evolutionary patterns of rock flows in complex environments. Through the analysis and comparison of experimental data, we comprehensively summarized the consequences of disaster risk resulting from dam failure. The results show that the grain size distribution of the model sand should be moderate; the composition of the particle size distribution has a significant impact on the collapse morphology of the dam after failure. The saturation line is the lifeline for the stability of the wake reservoir, and its level determines the degree of saturation of the wake in the reservoir. The breach was at the midpoint of the crest of the dam. The inflow volume at the time of the breach was 0.313 m³. According to the flow ratio relationship, the inflow volume at breach occurrence was equivalent to 1.78 times the total amount of a 1000-year flood and 1.19 times the total amount of a probable maximum flood (PMF). Analysis of the surface flow field revealed that the region with the highest flow velocity extended from the toe of the dam to Shangdi village; the impact on the village of Shizhou was limited to the backflow of the dam break and the gradual sedimentation of the tailings.

In response to the challenges posed by rapid development, wide-ranging disaster impact, and untimely warning of debris flow resulting from tailing dam failure, it is of great significance to study the mechanism of dam failure as well as the evolution law and affected area of debris flow for effective disaster prediction and risk assessment. Establish a 1:150 physical model for tailing dam failure test and combine it with RAMMS debris flow software to study the mechanism of tailing dam failure and the evolution law of rock flow in complex environments. By analyzing and comparing experimental data, the consequences of disaster risk following dam failure were summarized in a comprehensive manner. The results show that: The particle size distribution of the model sand should be moderate; The composition of particle size distribution has a significant impact on the collapse morphology of dam body after dam failure. The saturation line is the lifeline for tailing reservoir stability, and its level determines the degree of tailing saturation in the reservoir. The breach is situated at the midpoint of the dam crest. When the breach occurs, the inflow volume is 0.313m³. According to the flow ratio relationship, the inflow volume at breach occurrence is equivalent to 1.78 times the total amount of a 1000-year flood and 1.19 times the total amount of a probable maximum flood (PMF). The analysis of the surface flow field reveals that the region with the highest flow velocity extends from the dam toe to Shangdi village; The impact on Shizhou village is limited to the backwater of the dam break water flow and gradual sedimentation of tailings.

Land resources are being depleted due to global climate change, and as a result, infrastructures such as expressways and high-speed railways have no option but to be built in soft soil regions. Hence, the cyclic and post-cyclic behaviors of soft soil are vitally important. However, little attention has been devoted to this issue. In the current study, a series of cyclic triaxial tests and standard monotonic loading tests were carried out in order to investigate the cyclic and post-cyclic behavior of stabilized sand-containing soft soil. In addition, the stiffness evolution index model was proposed to describe the characteristics of stiffness evolution. The results show that for a given number of loading cycles, stiffness almost linearly decreases with the increase in sand content. The higher the confining pressure is, the greater the stiffness is. The cement content has the greatest impact on the stiffness evolution index. The stiffness evolution index model can provide a good description of experimental data. The initial value of post-cyclic axial strain is non-zero due to the accumulative strain caused by previous cyclic loading. Post-cyclic stress increases rapidly within a small range of strain and can reach peak stress with great speed. The post-cyclic initial tangent modulus increases from 1602 kPa to 4803 kPa as the cement content increases from 6% to 12%.