Hu, C.; You, Z-J.; Mao, H-y., and Hu, X-m., 2018. Assessing Impacts of Large-scale Coastal Land Reclamation on Marine Environment on the Coast of China. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1486–1490. Coconut Creek (Florida), ISSN 0749-0208. Coastal land reclamation increases at a high speed on the coast of China in the last few decades. It is estimated that nearly 65% of tidal flats around the Yellow Sea of China have been reclaimed. This study is to undertake a comprehensive study of the coastal land reclamation in China by analyzing the coverage area of index system and the determination method of weight. In order to undertake the comprehensive evaluation, a new assessment method is also developed by combining the analytic hierarchy process(AHP) with the Delphi method. The Multi Indexing model for assessing impacts of land reclamation project on marine environment has been established. The weight for multi indexes has been obtained based on the AHP and Delphi methods. The evaluation standard for assessing impacts of reclamation project on marine environment is also proposed. With these new standards, the newly developed model has been applied to undertake a case study for a large-scale land reclamation project at a coastal site of Caofeidian located in the center of Bohai Bay.

Against the backdrop of the global energy transition, offshore wind power has undergone rapid development. As a vital component of offshore wind power infrastructure, dry shrinkage cracking in concrete piles poses a significant threat to the safe and stable operation of offshore wind power systems. However, the fundamental mechanism of concrete pile cracking during dry shrinkage—particularly the coupled effects of moisture diffusion, meso-structural heterogeneity, and stress evolution—remains poorly understood, lacking a unified theoretical framework. This knowledge gap hinders the development of targeted anti-cracking strategies for offshore concrete structures. Hence, investigating the mechanism of dry shrinkage cracking is of substantial importance. This paper employs numerical simulation to explore the patterns and influencing factors of dry shrinkage cracking in concrete piles for offshore wind turbines, aiming to provide theoretical support for enhancing pile performance. A meshless numerical simulation method based on the smoothed particle hydrodynamics (SPH) framework is developed, which generates concrete meso-structures via a specific algorithm, discretizes the moisture diffusion equation, defines dry shrinkage stress terms, and introduces a fracture coefficient to characterize particle failure, enabling the simulation of concrete dry shrinkage cracking processes. Simulation schemes are designed for varying aggregate percentages, aggregate particle sizes, dry shrinkage coefficients, and moisture diffusion coefficients, using a 100 mm-diameter circular concrete model. Qualitative results reveal the following: Increased aggregate percentages lead to more uniform moisture diffusion, with dry shrinkage crack number and length first increasing and then decreasing; larger aggregate particle sizes exacerbate moisture diffusion non-uniformity and intensify dry shrinkage cracking; higher dry shrinkage coefficients correlate with increased crack number and length; elevated moisture diffusion coefficients accelerate surface water loss, with cracking severity first increasing and then decreasing. The proposed SPH-based meshless method effectively simulates dry shrinkage cracking in offshore wind turbine concrete piles, demonstrating the significant impact of different factors on moisture diffusion and cracking patterns. This study offers insights for applying the SPH method in related fields, deepens the understanding of concrete dry shrinkage cracking mechanisms, and provides a theoretical foundation for the design and optimization of offshore wind power concrete piles.

Cracks in rock and concrete have a great adverse effect on the stability of engineering structures; however, there are few studies on X-shaped fissures which widely exist in rock and concrete structures. Based on this background, three-point bending fracture tests of SCB specimens containing X-shaped fissures are carried out. The momentum equations in the SPH method are improved, and the crack propagations of SCB specimens under three-point bending are simulated. The results show that cracks grow simply along the vertical direction in the sample with no X-shaped fissures, and the existence of an X-shaped fissure changes the crack growth path and final failure modes of the SCB samples. The crack propagation simulation results are consistent with the experimental results, which verifies the rationality of the improved SPH method. The load–displacement curves mainly present three typical stages: the initial compaction stage, linear elastic deformation stage, and failure stage. The peak load decreases first then increases with an increase in eccentricity. With an increase in X-shaped fissure length and decrease in X-shaped fissure angle, the peak load decreases. The damage counts remain at 0 at the initial loading stage, corresponding to the initial compaction stage and the linear elastic deformation stage, and increase sharply at the later loading stage, corresponding to the failure stage, which is consistent with the experimental results. The influence mechanisms of X-shaped fissures on the crack propagation paths are discussed; the existence of different X-shaped fissure morphologies aggravate the tensile stress concentration at specific positions, leading to different crack propagation modes in the experiments. The research results can provide a certain reference for understanding the failure mechanisms of engineering structures containing X-shaped fissures and promote the applications of the SPH method into the simulations of cross-fissure crack propagations.

The existence of cracks is a key factor affecting the strength of concrete. However, traditional numerical methods still have some limitations in the simulation of crack growth in fissured concrete structures. Based on this background, the numerical treatment method of particle failure in smoothed particle hydrodynamics (SPH) is proposed, and the generation method for concrete meso-structures under the smoothed particle hydrodynamics (SPH) framework is developed. The concrete meso-models under different pre-existing micro-fissure inclinations and bridge angles (the inner tip line of the double pre-existing micro-fissure is defined as a bridge, and the angle between the bridge and the horizontal direction is defined as the bridge angle) were established, and numerical simulations of the crack propagation processes of concrete structures under tensile stress were carried out. The main findings were as follows: The concrete meso-structures and the pre-existing micro-fissures all have great impacts on the final failure modes of concrete. The stress–strain curve of the concrete model presents four typical stages. Finally, the crack initiation and propagation mechanisms of fissured concrete are discussed, and the application of smoothed particle hydrodynamics (SPH) in crack simulations of fissured concrete is prospected.

Offshore wind power plays a crucial role in the global development of clean energy. However, the concrete piles of offshore wind turbines face the problem of frost heave cracking in cold sea areas. In this study, the meso-scale frost heave cracking mechanisms of concrete is investigated. Traditional smoothed particle hydrodynamics (SPH) method is improved. A fracture marker is introduced to simulate the progressive failure processes of particles, and a method for generating the meso-structures of concrete is proposed. By embedding the temperature equation and combining with the equivalent thermal expansion method, the frost heave cracking process of concrete is simulated. Simulation schemes with different aggregate percentages, aggregate sizes, pore percentages, and prefabricated fissure angles are set up to study the influence of various factors on the frost heave cracking of concrete. The results show that different factors have a significant impact on the frost heave cracking of concrete. The improved SPH method can effectively simulate the frost heave cracking process of concrete. Compared with traditional numerical methods, it has more obvious advantages in dealing with particle failure and complex meso-structures. This study reveals the laws of concrete frost heave cracking under different meso-structure factors, providing a solid theoretical basis for the anti-frost heave design of concrete piles in offshore wind farms.