Abstract:Red sandstone slopes are widely distributed in the rainy regions of southern China, where rainfall-induced infiltration, pore water pressure accumulation, and water-rock weakening often lead to deformation and instability. To evaluate slope stability under such conditions, this study develops an improved mutation model considering the water-rock weakening effect and integrates it with FLAC3D numerical simulation. The combined approach is used to investigate the stability of red sandstone slopes and to analyze the variation of displacement and safety factor under dynamic water pressure and static water pressure. The results indicate that rainfall significantly decreases slope stability. As rainfall duration increases, slope displacement gradually enlarges, while the accumulation of pore water pressure further reduces rock mass strength. A comparative analysis of the limit equilibrium method, the improved mutation model, and FLAC3D simulation shows that the safety factor decreases after rainfall, and that FLAC3D provides a more accurate evaluation when water pressure and dynamic effects are taken into account. The study demonstrates that the improved mutation model, together with FLAC3D, can effectively characterize the stability evolution of red sandstone slopes under rainfall conditions, providing a practical and reliable basis for slope stability assessment.

Abstract:Due to the complex geological conditions and the well-developed jointed and fractured rock mass in Equatorial Guinea, the AM Highway project is exposed to a high risk of loosened strata and slope instability during blasting excavation. To ensure the safe and continuous construction of road-cut slopes, this study develops a real-time slope stability evaluation platform oriented toward cutting slopes. Based on the three-dimensional spatial analysis and interactive visualization capabilities of a GIS platform, a fuzzy comprehensive evaluation method is established by integrating rock mechanical parameters, topographic characteristics, and environmental factors such as rainfall and seismic effects. To reduce the subjectivity inherent in conventional weight determination, an AHP–Entropy combined weighting mechanism is proposed, in which expert judgment is coupled with information entropy to enhance the objectivity of weight assignment and its adaptability to spatial data variability. Furthermore, to characterize the fuzziness and randomness involved in slope stability grade determination, a cloud model is introduced Due to the complex geological conditions and the well-developed jointed and fractured rock mass in Equatorial Guinea, the AM Highway project is exposed to a high risk of loosened strata and slope instability during blasting excavation. To ensure the safe and continuous construction of road-cut slopes, this study develops a real-time slope stability evaluation platform oriented toward cutting slopes. Based on the three-dimensional spatial analysis and interactive visualization capabilities of a GIS platform, a fuzzy comprehensive evaluation method is established by integrating rock mechanical parameters, topographic characteristics, and environmental factors such as rainfall and seismic effects. To reduce the subjectivity inherent in conventional weight determination, an AHP–Entropy combined weighting mechanism is proposed, in which expert judgment is coupled with information entropy to enhance the objectivity of weight assignment and its adaptability to spatial data variability. Furthermore, to characterize the fuzziness and randomness involved in slope stability grade determination, a cloud model is introduced to describe the uncertainty of evaluation results, revealing the internal structure of stability grades and the transition characteristics between adjacent levels. By coupling the fuzzy evaluation model with GIS-based three-dimensional spatial analysis and automated data extraction, the proposed platform enables visualized and near real-time stability assessment. A case study conducted at the K81 section of the AM Highway in Equatorial Guinea indicates a potential risk of instability, suggesting that slope cutting and vegetation-framed surface protection measures should be implemented to ensure construction safety. The proposed method provides a practical reference for dynamic stability evaluation and engineering decision-making of road-cut slopes under complex geological conditions.

Abstract:To reveal the influence of residual mortar on the surface of recycled cement concrete aggregate obtained from demolished airport pavement on asphalt interfacial adhesion stability and moisture damage susceptibility, this study conducted a comparative investigation of the interfacial behavior between recycled aggregate and natural limestone. Fundamental property tests, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), pull-off tests, contact angle measurements, surface free energy analysis, and molecular dynamics simulation were employed. The results showed that the recycled aggregate surface was covered with porous residual mortar containing hydration products such as Ca(OH)?, CaCO?, and C-S-H, which increased water absorption and enhanced interfacial moisture sensitivity. The pull-off test results indicated that the interfacial bond strengths of limestone and recycled aggregate under dry conditions were 2.97 MPa and 2.60 MPa, respectively, suggesting that recycled aggregate could still develop a certain level of interfacial adhesion. After 96 h of water immersion, the corresponding bond strengths decreased to 2.31 MPa and 1.31 MPa, with strength loss rates of 22.2% and 49.6%, respectively. Surface free energy analysis showed that the adhesion work of the recycled aggregate–asphalt interface was 102.74 mJ/m2, slightly higher than that of the limestone–asphalt interface, which was 98.92 mJ/m2. However, the moisture stability index decreased from 0.99 to 0.78, indicating that water more readily weakened the interfacial bonding of recycled aggregate. Molecular dynamics simulation further revealed that water molecules tended to occupy the active sites on SiO? and C-S-H surfaces, thereby reducing the binding energy of the asphalt–mineral interface. Mixture-level verification showed that, after adding 1% hydrated lime, the freeze-thaw splitting tensile strength ratio of recycled aggregate asphalt mixtures reached 82.16%–86.11%, satisfying the specification requirement. These results indicate that the moisture damage of the recycled aggregate interface mainly originates from the porous structure and hydrophilic mineral composition of residual mortar. Nevertheless, recycled aggregate still has application potential when used with an appropriate replacement ratio and anti-stripping treatment.

Abstract:The study aims to review the development history and design methodologies of long-life asphalt pavements and to provide a reference for improving localized design theories and engineering applications. Based on literature synthesis and comparative analysis, a systematic review is conducted on the conceptual framework, development history, structural design methods, and material design of long-life asphalt pavements.The study focuses on comparing the differences between the “perpetual pavement” design systems in Europe and the United States, which are primarily based on flexible pavement structures, and the structural system in China, which predominantly adopts semi-rigid base courses. The evolution of long-life pavement design from empirical approaches to mechanistic–empirical methods is summarized. In addition, key design criteria based on tensile strain at the bottom of the asphalt layer and compressive strain at the top of the subgrade are identified, along with the functional requirements of materials in each structural layer.The results indicate that a relatively mature design system for long-life pavements has been established in developed countries, with its core concept centered on achieving a perpetual pavement through strain-controlled design. In contrast, challenges remain in China regarding the consistency of design criteria, the long-term performance of semi-rigid base structures, and the integration of material and structural design. Therefore, it is recommended to strengthen the concept of layer-specific durability design, refine strain-based design criteria, and promote integrated design approaches that couple material performance with structural response.

Abstract:Ultra-high performance seawater sea-sand concrete (UHPSSC) can be prepared using locally available raw materials and exhibits excellent mechanical properties, indicating its broad application potential in deep-sea and far-sea engineering. Existing research on the mechanical properties of UHPSSC has been mainly conducted under quasi-static loading conditions, and investigations into its dynamic mechanical behavior are still lacking. To clarify the dynamic mechanical properties of UHPSSC reinforced with high-toughness polypropylene (HTPP) fibers, axial compression tests were carried out with varying HTPP fiber contents and loading rates. The failure modes and stress-strain relationships of UHPSSC were obtained, and the effects of loading rate and HTPP fiber content on its axial compressive behavior were determined. Finally, a dynamic/static stress-strain relationship model for UHPSSC was established based on the experimental data. The evaluation results indicate that the proposed model can well predict the dynamic and static stress-strain behavior of UHPSSC.

Abstract:Currently, on steel bridges, the steel foundation for metal beam-column barriers and the steel curb are typically two separate structures constructed independently. This leads to complex construction procedures, extensive on-site welding work, and low construction efficiency.This paper adopts a multifunctional integrated design concept, proposing an integrated structural scheme for the steel foundation and steel curb of metal beam-column barriers. Theoretical analysis, finite element simulation, and full-scale impact test with real vehicle were conducted to evaluate the scheme.The results indicate that this solution meets the vehicle impact load requirements for HA-class metal beam-column barriers, It integrates multiple functions, including foundation connection, rainwater drainage, and linear guidance, while reducing welding procedures.. This enhances construction efficiency and promotes prefabrication, the engineering application performed well, providing design references and technical support for similar projects.

Abstract:The layout selection design of system interchanges on mountainous highways is significantly restricted by terrain and surface features, so standard interchange configurations are often not directly applicable. Taking the design of a dominant system interchange for a highway project in Guangxi as a case study, this paper presents a layout concept for modified double trumpet system interchanges. It intends to offer a reference scheme for the design of system interchanges on a wide range of mountainous highways, particularly for sites subject to multiple constraints: limited layout space across successive quadrants, tight land occupation quotas for interchanges, mandatory avoidance of basic farmland, and the elimination of weaving movements between mainline and ramp traffic.Developed on the basis of a conventional double trumpet interchange, this design eliminates potential weaving sections on ramps and excessive detour mileage through ramp segmentation. While circumventing critical restricted features, the layout reduces land use by over one quarter and earth fill volume by nearly 70 %. Integrated horizontal and vertical alignment design is prioritized throughout the design process, and relevant design experiences are worthy of sharing and discussion. This paper proposes an innovative layout pattern for system interchanges, summarizes the key and difficult issues that should be addressed during the design of such interchanges, and delivers a new approach to the conceptual design of system interchanges.

Abstract:During the construction of cantilever-cast arch bridges, temperature variations significantly influence the geometric development and stress distribution of the arch ribs, thereby having a significant impact on construction control accuracy and structural safety. Consequently, accurately predicting temperatures at critical cross-sections during the construction phase is of great importance for implementing temperature early warning systems and controlling the geometry of the arch ribs. However, temperature time series collected during the construction period often exhibit distinct characteristics such as non-stationarity, multi-timescale coupling and noise interference, making it difficult for traditional prediction methods to simultaneously achieve both prediction accuracy and computational efficiency in short-term forecasting. To address this issue, this paper proposes a temperature prediction method that integrates signal decomposition with intelligent optimisation strategies. Firstly, Variational Modal Decomposition (VMD) is employed to perform a multi-scale decomposition of the raw temperature time series, whilst the Crown Porcupine Optimisation (CPO) algorithm is introduced to adaptively optimise the number of modes and penalty factors, thereby enhancing the quality of the decomposition. Subsequently, the modal components are screened based on the Variance Contribution Ratio (VRC) to extract effective features that contribute significantly to temperature variations, thereby reducing the feature dimension and minimising noise interference. Finally, the filtered modal components are fed into a Long Short-Term Memory (LSTM) network, whose parameters have been optimised by CPO, for prediction, and the final prediction results are obtained through stacked reconstruction. Comparison of experimental data indicates that, compared with the LSTM, EMD-LSTM, VMD-LSTM and VMD-PSO-LSTM models, the proposed model reduces the MAPE by 47.72%、42.41、39.54% and 4.19% respectively, whilst improving computational efficiency by 43%. This provides a technical reference for temperature prediction, construction control and structural safety management during the construction phase of cantilever-poured arch bridges.

Abstract:In swivel bridge construction, spherical hinge weighing tests are an important means to obtain the mechanical parameters of the rotating system. To improve the real-time performance of the weighing process and achieve fast and accurate output of calculation results. This study analyzes the response characteristics of load and displacement before and after the rigid-body rotation of the spherical hinge based on the continuously monitored load and displacement data obtained during the jacking process, and investigates the method for determining the critical point. On this basis, an online calculation software for spherical hinge weighing of swivel bridges is developed to realize the real-time calculation of key parameters, including unbalanced moment, eccentricity, and frictional resistance moment of the spherical hinge, as well as to perform counterweight back-calculation. The software is applied to a practical swivel bridge project for spherical hinge weighing tests. The results show that a displacement of about 1.5 mm at the upper turntable during the jacking process can be used as a reference for determining the critical point of rigid-body rotation. The calculated results agree well with the measured data. The results can provide a reference for real-time analysis and application of weighing and unbalanced counterweight tests in similar bridges.

Abstract:Dedicated reinforcement schemes for the anchorage zone of six-hole flat anchor bearing plates in ordinary concrete T-beam flanges are currently scarce. Furthermore, high-precision numerical models that simultaneously consider detailed structures—such as grouting holes and stiffening ribs—are lacking, as are accurate calculation methods for bursting force and design bases for this specific configuration. Consequently, this study conducts a stress analysis and reinforcement optimization design for the anchorage zone. A combined approach of theoretical analysis, refined finite element simulation, and scale model testing was adopted. Using HyperMesh and Abaqus, a high-precision finite element model incorporating a concrete damage model and detailed structures was established. To address the challenge of missing stress data at the section center caused by prestressing ducts, an “Offset Path Averaging Method” was proposed to calculate the bursting force. Additionally, a general formula for the position of the bursting force resultant, applicable to flat anchors with varying numbers of holes, was derived. An optimized reinforcement design scheme for the anchorage zone of the six-hole flat anchor bearing plate was proposed and validated through corresponding model tests. The results indicate that the optimized reinforcement scheme maintains a crack width of less than 0.05 mm under tensioning control stress, with steel bar strains far below the yield value, demonstrating sufficient safety reserves. The error between the finite element predicted cracking load (937 kN) and the experimental value (896 kN) is only 4.4%, indicating high model accuracy. This study provides a theoretical basis and technical support for the design of similar engineering projects.