This study introduces a coupled peridynamics (PD) and smoothed particle hydrodynamics (SPH) model to handle the complex physical processes in concrete dam structures subjected to near-field underwater explosions. A robust coupling algorithm is applied to ensure accurate data exchange between PD and SPH domains, enabling the simulation of fluid-structure interactions. To account for the material behavior under high strain rates, a rate- dependent concrete model is integrated into the PD-SPH framework. The developed PD-SPH model is validated through simulations of centrifugal model tests, with results benchmarked against experimental findings and finite element method (FEM) predictions. The simulation captures key damage features, including horizontal tensile cracking at the dam head and an oblique penetrating crack in the dam body, forming an angle of approximately 17 degrees relative to the horizontal. Velocity and strain responses at critical monitoring points demonstrate strong agreement with FEM results, showcasing the model's capability in accurately predicting the structural responses and failure of concrete dams caused by underwater explosions. To the best of the authors' knowledge, research applying a coupled PD-SPH model to concrete structures under blast loading is still rare, particularly when considering the entire physical process, from explosive detonation to structural failure, accounting for fluid-structure interactions.

Due to the insufficient burial depth of shallow-buried foundation bridges, foundation voiding easily occurs during floods or rapid water flows. When heavy vehicles pass over these partially voided bridges, the stress state of the foundation deteriorates instantaneously, causing critical components to exceed their load-bearing capacity in a short period, leading to a chain reaction that results in the rapid collapse and overall failure of the bridge structure. Previous numerical simulations of bridge water damage often neglected the strong coupling between water flow, soil, and structure during the scouring process. This paper applies a fluid-solid coupling simulation modeling method for bridge damage behavior under scouring action to study the structural damage behavior of shallow-buried foundation bridges under the combined effects of flood scouring and heavy vehicle load. This method employs point cloud reverse engineering technology to solve the difficult problem of converting the complex scour morphology around the foundation under flood scouring into a structural model, and investigates the multi-hazard damage behavior of shallow-buried foundations by coupling extreme hydraulic effects on the pier surface and placing the most unfavorable heavy vehicle loads on the bridge deck.

With transportation's rapid growth, ship-bridge collisions occur frequently, causing substantial losses. Ship-bridge anticollision facilities should not only protect the structural integrity of bridges but also minimise ship damage. This paper designs a novel ship-bridge anti-collision device based on a trapezoidal foam-filled composite sandwich structure. Using the finite element software LS-DYNA, a ship-anti-collision device-bridge collision model was established, taking into account pile-water-soil coupling. The study investigates the selection of box materials, filling materials and wall thickness for the novel anti-collision device. By analysing the damage characteristics of the ship, anti-collision device and pier under typical collision loads, the optimal material properties were determined. The impact resistance of the optimised device was evaluated under different ship speeds and collision angles, demonstrating that the novel anti-collision device exhibits excellent buffering and energy absorption, effectively reducing the peak collision force, extending the collision duration and reducing damage to the ship's bow structure.

High-rise pile cap structures, such as sea-crossing bridges, suffer from long-term degradation due to continuous corrosion and scour, which seriously endangers structural safety. However, there is a lack of research on this topic. This study focused on the long-term performance and dynamic response of bridge pile foundations, considering scour and corrosion effects. A refined modeling method for bridge pile foundations, considering scour-induced damage and corrosion-induced degradation, was developed by adjusting nonlinear soil springs and material properties. Furthermore, hydrodynamic characteristics and long-term performance, including hydrodynamic phenomena, wave force, energy, displacement, stress, and acceleration responses, were investigated through fluid-structure coupling analysis and pile-soil interactions. The results show that the horizontal wave forces acting on the high-rise pile cap are greater than the vertical wave forces, with the most severe wave-induced damage occurring in the wave splash zone. Steel and concrete degradation in the wave splash zone typically occurs sooner than in the atmospheric zone. The total energy of the structure at each moment under load is equal to the sum of internal energy and kinetic energy. Increased corrosion time and scour depth result in increased displacement and stress at the pile cap connection. The long-term dynamic response is mainly influenced by the second-order frequency (62 Hz).

Bridge piers embedded in a riverain region are commonly supported by pile foundations. This provides a flexible restraint to the bridge pier instead of a theoretical rigid foundation type. In this work, a cylindrical bridge pier with a monopile foundation is introduced as an example. A modeling framework is proposed to investigate the dynamic response of bridge piers to the impact of flash flooding. The fluid-structure interaction is directly investigated via a two-way fluid-structure coupling approach and the p-y springs distributed over the interface between the soil and pile are adopted to model the lateral restraints from the soil. The effect of the soil-structure interaction (SSI) on the structural dynamic response is investigated on the basis of 3D numerical models with and without a pile foundation. Moreover, the soil around the pile foundation is vulnerable to erosion by flood flow. This continuous exposure of the pile foundation reduces the lateral load bearing capacity and consequently increases the dynamic responses of bridge structures to flash flooding. To demonstrate the effects of increased exposure of bridge pile foundations on structural dynamic responses, several different scour depths with scour ratios ranging from 0 to 0.5 are included in the numerical analysis. Two different considerations of the pile bottom are included in this study: completely fixed and only vertically fixed. The behavior of bridge piers subjected to flash flooding is thoroughly analyzed, and the damage mechanisms for these two foundation types are investigated. The relationships between peak responses and fundamental periods are determined via regression analysis.

Buried pipes are widely used for submarine water transportation, but the complex operating conditions in the seabed pose challenges for the modeling of buried pipes. In order to more accurately capture the dynamic behavior of the buried pipes in the seabed, in this study, considering the pipeline and soil as a systematic structure is proposed, improving the fluid-structure interaction four-equation model to make it applicable for the calculation of buried pipe system modes. After verifying the practicality of the model, considering the external seawater as uniform pressure, the coupling at the joints, and the Poisson coupling of submarine pipelines during transient processes are discussed, revealing that structural vibrations under both forms of coupling will cause greater hydraulic oscillations. The impact of soil elastic modulus on the system's response is further discussed, revealing that increasing the modulus from 0 to 1015 Pa raises the wave speed from 498 m/s to 1483 m/s, causing a 40% increase in the amplitude of pressure oscillations. Finally, the vibration modes of the combined structure of pipe wall and soil are discussed, revealing that the vibration modes are mainly dominated by water hammer pressure, with the superposition of pipeline stress waves and soil stress waves. In this study, the dynamic behavior of submarine pipelines is elucidated, providing a robust foundation for regulating and mitigating fatigue failures in such systems.

Shaoguan was hit by a extremely heavy rainstorm, and the mountain watercatchment of Dabaoshan Tunnel in the southern of Beijing HongKong Macao Expressway in Guangdong increased sharply. Due to therapid rise of groundwater level, water and mud gushed at ZK141+227 ofDabaoshan, and serious water seepage occurred in other areas, bringing soilinto the tunnel, which seriously hindered the safe passage of the tunnel.According to the on-site investigation of water and mud gushing, it wasfound that there were branches sandwiched in the mud gushing out, andat the same time, it was found that there was water leakage at the foot ofsome walls where drainage holes were added. Based on the fluid structurecoupling mechanism, the seepage mechanism of highway tunnels was deeplyexplored, and the mechanical properties of tunnels under seepage were ana-lyzed through experimental data and numerical simulation. The experimentalresults show that under the action of seepage, the stress distribution of the tunnel lining changes, and the phenomenon of local stress concentration isobvious. When the seepage pressure reaches 3.5 MPa, cracks appear in thetunnel lining, with a total of 5 cracks. The distribution of cracks is closelyrelated to the seepage field. The numerical simulation further reveals theinteraction mechanism between the seepage field and the tunnel structure,confirming the influence of the seepage field on the stability of the tunnellining. When the seepage pressure increases to 4.0 MPa, the displacementchange rate of the tunnel lining reaches 0.3 mm/m, and the maximum liningstress is 15.7 MPa. The purpose of this study is to propose a maintenance planfor highway tunnels to improve their safety. Consider the impact of seepageon tunnel structure and adopt effective waterproofing and drainage design.Further research on the seepage mechanism and tunnel mechanical propertiesis recommended to provide more reliable theoretical support for engineeringapplications.