This study investigates the application of machine learning (ML) algorithms for seismic damage classification of bridges supported by helical pile foundations in cohesive soils. While ML techniques have shown strong potential in seismic risk modeling, most prior research has focused on regression tasks or damage classification of overall bridge systems. The unique seismic behavior of foundation elements, particularly helical piles, remains unexplored. In this study, numerical data derived from finite element simulations are used to classify damage states for three key metrics: piers' drift, piles' ductility factor, and piles' settlement ratio. Several ML algorithms, including CatBoost, LightGBM, Random Forest, and traditional classifiers, are evaluated under original, oversampled, and undersampled datasets. Results show that CatBoost and LightGBM outperform other methods in accuracy and robustness, particularly under imbalanced data conditions. Oversampling improves classification for specific targets but introduces overfitting risks in others, while undersampling generally degrades model performance. This work addresses a significant gap in bridge risk assessment by combining advanced ML methods with a specialized foundation type, contributing to improved post-earthquake damage evaluation and infrastructure resilience.

The compressive bearing capacity of a new type of concrete-expanded plate pile (NT-CEP pile) is significantly affected by the size of the bearing platform; however, research in this area remains limited. Therefore, this study investigates the effect of bearing platform size on the compressive bearing capacity of an NT-CEP pile foundation under combined vertical and horizontal loads. Using ANSYS finite element software, a four-pile model was established to analyze the failure behavior of the bearing platform and surrounding soil under these loads. The findings indicate that in an NT-CEP four-pile foundation, the bearing capacity of piles with a bearing platform increased by 66.67% compared with those without one. However, although the bearing capacity increased with platform size, this increase reduced after reaching a certain threshold. Optimal bearing performance was achieved when the platform size was 1.5 times the pile diameter from the edge to the pile center. High shear stress at the junction between the lower part of the platform and pile body suggested a potential stress concentration. The findings emphasize the importance of maintaining the optimal bearing platform size and reinforcing the connection between the platform and pile body to prevent local damage from affecting the overall bearing capacity.

The unclear impact of small-spacing construction between new road piles and railway piers in China's coastal soft soils can threaten the safety of operating high-speed railways. By field monitoring and numerical simulation tests, this study examines the deformation characteristics of railway piers and the surrounding stratum due to adjacent pile construction in soft soils. The stratum-lateral deformation (SLD) and the displacement of the bridge pier group with various pile-forming processes or pile construction schemes were measured in field monitoring. Furthermore, the intricate interplay between varying pile diameters and spacing was examined using comprehensive numerical methodology. On this basis, a comprehensive evaluation model for the Construction Deformation Comprehensive Index (CDCI) was established to compare the multi-stage combined effects of pile construction. The results indicate that the bored pile drilling and concreting procedures significantly affect the deformations of the stratum and pier. Specifically, a negative correlation is observed between stratum deformation and the bored pile's distance and depth. The most significant deformation is in the depth direction within the three-direction pier profile. The displacement amplitude caused by single-pile construction surpasses about 2-3 times that of non-construction. Additionally, the CDCI could provide valuable insights for evaluating the holistic impacts on stratum and pier deformation in similar pile construction projects.

The microstructure, mechanical properties, corrosion behavior, and potential for lightweight applications of Mg2Zn alloys enhanced with Cu and Ce were investigated. It was observed that the Ce and Cu-containing phases displayed various morphologies in the as-cast and extruded conditions. The extruded alloy, containing 0.8 wt% Ce and 0.5 wt% Cu, exhibited optimal mechanical properties, with the yield strength of 289 MPa, ultimate tensile strength of 336 MPa, and elongation of 15.8 %. Grain boundary and precipitation strengthening significantly contributed to the increase in yield strength. After four months of soil burial, the specimen surface showed localized pits and cracks, likely serving as anodes in the areas including Ce and Cu-containing phases. The corrosion rates in different soil environments paddy, vegetable, orchard, and corn fields were 2.029, 2.293, 2.133, and 1.986 mg & sdot;cm- 2 & sdot;d- 1, respectively indicating variations due to complex soil conditions. The corrosion products included Mg(OH)2 and Mg5(CO3)4(OH)2 & sdot;4 H2O, among others, throughout the burial period. Furthermore, model assembly in SolidWorks and static structural simulation with ANSYS confirmed the alloy's reliable load-bearing capacity, safety, and potential as the material for lightweight agricultural machinery.

With the development of the Chinese economy and society, the height and density of urban buildings are increasing, and large underground transportation hubs have been constructed in many places to alleviate the pressure of transportation. Commercial buildings are usually developed above the large underground transportation hubs, so the underground structures may have very shallow depths or no soil cover. The seismic response and damage mechanisms of such underground structures still need to be studied. In this paper, an example of a project in China is taken as an object to analyze the seismic response and damage mechanism of the structure after simplification. The spatial distribution of deformations and internal forces of such structures and the location of the maximum internal forces are obtained, and the effect of the frequency of seismic motions on the structural response is obtained. Finally, an elastoplastic analysis of such structures is carried out to assess the damage location and the damage evolution process.

This study was aimed to solve the problem of low spraying effect in spraying deposition on both sides of maize leaves with different height canopy by traditional high clearance sprayers. The spray effect can be improved by installing the canopy opener on the boom sprayer. The deflection model of the maize stalk was established by the interaction process between the canopy opener and the maize stalk. Based on the model, combined with the measurement of the structure and material property parameters of maize stalks in the bellbottom period, the finite element simulation and the high-speed video acquisition system experiment in the soil-bin were carried out under different working heights of the canopy opener (0.6 m, 0.8 m and 1 m). The test results showed that the bending angle of the stalk increased with the decrease in the working height of the canopy opener, and when the working height was reduced to a certain level, the stalk would break due to excessive disturbance. The simulation data and the high-speed image data have a good consistency, which is also consistent with the analysis results of the established theoretical model. The spraying effect of the canopy opener was further verified through field experiments, and the results showed that the canopy opener can significantly improve the uniformity of the droplets deposited in the canopy at different heights as well as in the adaxial and abaxial leaves. And this effect was increased with the decreasing of the working height of the canopy opener. Taking into account the seedling damage rate and the spray effect, the performance was better when the working height of the canopy opener was 0.8 m. At this point, the ratio of the droplet coverage rate and the droplet deposition density on the lower and middle canopy to upper canopy were 57.29% and 54.67% for lower to upper canopy, 75.64% and 72.41% for middle to upper canopy ratio. In addition, the ratio of the droplet coverage rate and the droplet deposition density on the abaxial and adaxial leaves were 78.82% and 65.85% in the upper canopy, 63.88% and 60.81% in the middle canopy, 58.39% and 54.64% in the lower canopy, respectively. The coefficient of variation of the droplet coverage and the droplet deposition density within canopy at different heights was 27.59% and 30.18%, respectively. This study provides theoretical basis, method and data support for the selection of the working height of the spraying opener during the bellbottom stage in maize cultivation.

Vibratory compaction significantly affects the construction quality of the subgrade in the road construction. Establishing a numerical analysis model for the subgrade compaction process helps visualize the compaction process and enhances the quality of compaction for the subgrade. Nowadays, such nonlinear characteristics between the vibratory roller and subgrade could be captured by establishing numerical simulation methods via finite element analysis, which effectively reduces the difficulty of the solution. In these methods, however, the elastoplastic model for the subgrade material tends to ignore the plastic accumulation characteristics of the soil under cyclic loading. Aiming at this problem, a finite element simulation method is proposed for the compaction process of subgrade. In the method, a bounding surface model considering plastic accumulation effect under cyclic loading is used for modelling the compacted soil material. Consequently, a three-dimensional finite element simulation model of drum-soil was established by using UMAT in the secondary development of ABAQUS. Compared with experimental data and popular models like the modified Cambridge model, the DruckerPrager criterion and the Mohr-Coulomb model, the finite element simulation method in this study demonstrates higher accuracy in terms of soil stress, settlement and drum acceleration, confirming its effectiveness. Finally, the dynamic changes in stress and strain during the compaction and the effects of the excitation forces on compaction were analyzed by the finite element simulation method.

As an essential component for the transportation of oceanic oil and gas supplies, it is crucial to ensure the efficient operation of submarine pipelines. The fatigue failure of submarine pipelines occurs frequently under the combined effects of currents, waves and soil. Firstly, a pipe-soil interaction suspended pipeline model was developed, which could be used to simulate the mechanical behavior of pipes and the dynamic response of the combined loads of waves and currents. Then, the effects of soil properties, current direction and suspended length on the stress distribution and dynamic mechanical response of submarine suspended pipelines were investigated. In addition, the vibration characteristics of suspended pipelines affected by soil were revealed. At last, according to the vortex-induced resonance evaluation and fatigue life assessment method, the critical length of suspended pipelines for the Bohai sea was determined. The results show that the stress change in the center of the suspended reaches the most significant for the pipeline with a length of less than 20m. When the suspended length exceeds 20m of the pipeline, the connection between the suspended and the buried shows the most dramatic stress fluctuations. Meanwhile, the cumulative damage of the submarine suspended pipeline entering the soil becomes the maximum, and fatigue failure often occurs in this position. The results are expected to provide an important theoretical basis in safe operation and repair decision of submarine pipeline.