The foundation conditions of piers for multi-span long-distance heavy-haul railway bridges inevitably vary at different locations, which may lead to non-uniform ground motions at each pier position, potentially causing adverse effects on the bridge's seismic response. To investigate the seismic response of bridges and the running safety of heavy-haul trains as they cross the bridge during an earthquake, a three-dimensional heavy-haul railway train-track-bridge (HRTTB) coupled system model was developed using ANSYS/LS-DYNA. This model incorporates the nonlinear behavior of critical components such as bearings, lateral restrainers, piers, and wheel-rail contact interactions, and it has been validated against field-measured data to ensure reliable dynamics parameters for seismic analysis. A multi-span simply supported girder bridge from a heavy-haul railway (HHR) was employed as a case study, in which a spatially correlated non-stationary ground motion field was generated based on spectral representation harmonic theory. Comparative analyses of the seismic responses under spatially varying ground motions (SVGM) and uniform seismic excitation conditions were performed for the coupled system. The results indicate that the presence of heavy-haul trains prolongs the natural period of the HRTTB system, thereby appreciably altering its seismic response. At lower apparent wave velocities, more piers exhibit a low-response state, and some pier bases enter the elastic-plastic stage under local site effects. Compared with the piers, the bearings show higher sensitivity to seismic inputs; fixed bearings experience damage when subjected to traveling wave effects and local site effects, which is subsequently followed by the failure of lateral restrainers. Train running safety is markedly reduced when crossing local soft soil site conditions. The conclusions drawn from this study can be applied in the seismic design and running safety assessment of HHR bridge systems under SVGM.

Pile-supported embankments are one of the most commonly used techniques for ground improvement in soft soil areas. Existing studies have mainly focused on embankments supported by end-bearing piles under static loading, with limited research on floating pile-supported embankments under cyclic traffic loading. In this study, model tests for unreinforced floating, unreinforced end-bearing, geosynthetic reinforced floating, and geosynthetic reinforced end-bearing pile-supported embankments were conducted. Cyclic traffic loading was simulated using a three-stage semi-sinusoidal cyclic loading. Comparative analyses and discussions are performed under floating and end-bearing conditions to investigate the influence of floating piles on the soil arching evolution and membrane effect under cyclic loading. The results indicate that floating piles result in earlier stabilization of surface settlement. There is less arching and membrane effect induced by floating piles, and the arching does not continue to degrade under cyclic loading. Less membrane effect in floating pile-supported embankments results in less geosynthetic and pile strain. The degree of membrane effect in floating pile-supported embankment largely depends on the pile-end condition.

With the widespread application of deep excavation projects, deformation control of diaphragm walls and management of surrounding soil displacement have become major challenges in the engineering field. To address these issues, this study proposes a prefabricated multi-limb composite concrete-filled steel tube (CFST) internal support system. The mechanical performance and deformation characteristics of the fixed ends of the system were systematically analyzed through axial compression tests and numerical simulations.First, based on the CFST stress-strain model, the constitutive model was modified to account for the effects of stiffening ribs, and a stress-strain relationship model for mold bag concrete was introduced. The simulation results demonstrate that the modified model can accurately predict the stress behavior of the fixed ends. Next, to characterize the overall mechanical response of the structure, a load-displacement relationship model was established. This model, which is closely related to the CFST strength grade, effectively captures changes in the structural performance.The results indicate that during loading, the CFST internal support system exhibits good stiffness and load-bearing capacity. With an increase in the concrete strength grade, the yield load increases by 12 %, and the ultimate strain decreases by 27.76 %, significantly enhancing the mechanical performance of the structure. This study not only deepens the understanding of the design principles for CFST internal support systems but also introduces new theoretical frameworks and calculation methods, providing strong support for engineering design with broad application prospects.

For well-founded decisions in sustainable timber harvesting, it is important to know the preferences of different stakeholders. The concept of sustainable timber harvesting is to incorporate economic, social, and environmental criteria. In a previous study, 33 criteria were identified by forest experts as relevant for evaluating sustainability. To assess the importance of these criteria, an online survey was conducted among Austrian stakeholders between April and May 2023, in which 610 people were invited to participate and which resulted in a response rate of 47%. The survey participants were primarily male (94%), with an average age of 47 and an average of 20 years of work experience. The key criteria for sustainable harvesting that were unanimously mentioned by the stakeholders on the basis of a Likert scale, included occupational hazards, residual stand damage, loss of wood quality due to poor work performance, biomass regeneration, water erosion, noise exposure, soil rutting, physical workload, working conditions, and vibration exposure. Younger or less experienced workers generally rated the criteria as less important than older and more experienced workers. These identified preferences will inform the development of a decision support model for sustainable timber harvesting using these criteria as input parameters.

For noncrushable sand, this paper describes the experimental phenomenon of the opposite turning directions of stress-dilatancy curves between sands before and after cementation. Then, based on the thermomechanical framework and Legendre transformation, the stress-dilatancy model is obtained from the dissipation function. This stress-dilatancy model considers the coupled effect of bond breakage and rearrangement energy. This model also incorporates the mechanism that cementation-improved strength leads to the opposite turns of sands before and after cementation. Compared with the other four existing stress-dilatancy models, this paper's model can depict the opposite turning directions of stress-dilatancy curves between uncemented and cemented sands. This stress-dilatancy model is also verified through five types of cementation: colloidal-silica-cemented sand, (CaCl2+Na2SiO3) cemented sand, naturally bonded sand, microbially induced carbonate precipitation (MICP)-cemented sand, and portland cement-treated sand. The broader application of the model is that it can also be used for crushable sand with particle breakage, as well as artificially cemented sand after freeze-thaw damage.

The aim of the present study is to assess the impact of rotational anisotropy on the undrained bearing capacity of a surface strip footing over an unlined circular tunnel on spatially variable clayey soil. The finite-difference method (FDM) is utilised to perform both deterministic and stochastic analyses. The Monte Carlo simulation approach is used to estimate the mean stochastic bearing capacity factor (mu Npro) and probability of failure (pf) of the entire system. The responses are evaluated for different geometric and spatially variable parameters and the strata rotation angle (beta). The failure patterns and the required factor of safety (FSr) corresponding to a specific probability of failure (e.g. pft = 0.01%) are determined for various parameters. The results obtained for the rotational anisotropy (beta$\ne \;$not equal 0) are observed to be significantly different from those for horizontal anisotropic structure (beta = 0), and considering only the horizontal anisotropic structure may lead to the overestimation or underestimation of the response of the structure.

Here, a seismic-response analysis model was proposed for evaluating the nonlinear seismic response of a pile-supported bridge pier under frozen and thawed soil conditions. The effect of a seasonally frozen soil layer on the seismic vulnerability of a pile-supported bridge pier was evaluated based on reliability theory. Although the frozen soil layer inhibited the seismic response of the ground surface to a certain extent, it exacerbated the acceleration response at the bridge pier top owing to the low radiation damping effect of the frozen soil layer. Furthermore, the frozen soil layer reduced the lateral displacement of the bridge pier top relative to the ground surface by approximately 80%, thereby preventing damage caused by earthquakes, such as falling girders. Compared to the thawed state of the ground surface, the bending moment of the bridge pier in frozen ground increases. However, the bending moment of the pile foundation in frozen ground decreases, thereby lessening the seismic vulnerability of the bridge pile foundation. The results of this can provide a reference for the seismic response analysis and seismic risk assessment of pile-supported bridges in seasonally frozen regions.

The primary goal of this study is to provide an efficient numerical tool to analyze the seismic performance of nailed walls. Modeling such excavation supports involves complexities due partly to the interaction of support with soil and partly because of the amplification of seismic waves through an excavation wall. Consequently, innovative modeling is suggested herein, incorporating the calibration of the soil constitutive model in a targeted range of stress and strain, and the detection of a natural period of complex systems, including soil and structure, while benefiting from Rayleigh damping to filter unwanted noises. The numerical model was achieved by simulating a previous centrifuge test of the excavation wall, manifested at the pre-failure state. Notably, the calibration of the soil constitutive model through empirical relations, which replaces the numerical reproduction of an element test, more accurately simulated the soil-nail-wall interaction. Two factors were crucial to a successful result. First, probing the natural period of the complicated geometry of the model by applying white noises. Second, considering Rayleigh damping to withdraw unwanted noises and thus assess their permanent effects on the model. Rayleigh damping was applied instead of filtering the obtained results.

The fatigue life of a monopile-supported offshore wind turbine (OWT) is substantially influenced by the support conditions which inevitably changes during its service life. This study performed fatigue analyses of monopilesupported OWTs with varied support conditions, which not only determine the correlation between the support condition and the fatigue damage of OWT, but also predict fatigue lifetime of OWT for different support condition scenarios. A simplified finite element model of a 10 MW OWT is constructed. Long-term wind and wave data, measured over 25 years in the South China Sea, are utilized to determine the fatigue loads. The results show that the fatigue damage incurred in the parked status of the OWT is negligible, accounting for 0.84% of the total fatigue damage. Both support stiffness and damping have significant effects on the fatigue damage of OWT, both exhibiting a strictly negative correlation with the fatigue damage of OWTs. When stiffness and damping decrease at high rates, the total fatigue damage of the structure exceeds 100%, indicating that fatigue damage may occur in the OWT structure during its life cycle. This study provides a reference for fatigue design and may contribute to the assessment of fatigue damage in OWT.

Okra (Abelmoschus esculentus) is an important vegetable in Ethiopia due to its nutritional value and culinary uses. However, its production is hindered by several challenges. Key issues include diseases like powdery mildew, fusarium wilt, and viral infections, which significantly reduce yields, and pests such as aphids, whiteflies, and fruit borers that further damage crops. The scarcity of improved okra varieties and insufficient drought management exacerbate these challenges. Farmers' perceptions of okra as a low-value crop affect investment and cultivation practices. Additionally, drought, compounded by poor irrigation infrastructure, poses a severe threat to okra production. Despite these challenges, Ethiopia's diverse agro-climatic conditions and fertile soils in regions like Amhara and Oromia offer favorable environments for cultivating okra, with potential yields reaching up to 20 tons per hectare under optimal management. To overcome these constraints, it is essential to improve disease and pest management, develop and distribute drought-resistant varieties, and educate farmers on better practices. Changing perceptions through awareness and community engagement, coupled with supportive government policies, are crucial for enhancing okra production, thereby improving food security and economic stability for Ethiopian farmers in the future.