An artificial floating reef is an important part of the coastal ecological corridor. The large-scale construction of floating reefs by optimizing mooring methods can effectively improve the ecological effects of coastal projects. The artificial floating reef belongs to coastal engineering, and wave resistance is fundamental to its structural design. In this paper, the method for processing coupling forces and motion, the method for judging the floating reef out of water surface, and the method for correcting velocity and acceleration of water mass points are elaborated in detail by using the finite element method and lumped-mass mooring model. By comparing and analyzing the results of physical experiment and numerical simulation, the correctness of the numerical model is verified. Finally, the diachronic variation of pitching angle of floating reef, the tension of the mooring rope, and the total tension of the fixed points of the fishing net were analyzed by the dynamic response numerical mode with a new type of mooring. The purpose of the current study was to provide a basis for the optimization of structure shape, the matching of floating body, and the counterweight of artificial floating reef.

In the restoration of ancient water engineering, the loss of fine soil particles from the ancient riverbank can easily cause seepage instability problems such as piping during the flood transient process. This paper explores the influence mechanism of flood fluctuation on soil seepage stability based on indoor experiments, field monitoring and saturated-unsaturated soil seepage theory. The paper obtains the soil-water characteristic curve of unsaturated soil using laboratory tests, builds the transient seepage finite element model of porous media and modifies parameters monitoring data to verify the numerical analysis results. The results showed that the groundwater level, pore water pressure and seepage hydraulic gradient had changed. The maximum pore water pressure between the ancient riverbank and antiseepage structure increased by 13.4%, the maximum hydraulic gradient at the toe of the riverbank increased by 49.3% and the instability of seepage significantly increased. Through the modified lime grouting between the ancient riverbank and the antiseepage structure, the structure of the soil mass was changed, and the maximum hydraulic gradient was reduced by 55.6%, which restrains piping damage. This study can be used in the restoration of ancient riverbanks to solve piping problems.

Wave features and propagation characteristics during typhoons are the key factors to study the dynamic response of ocean engineering and coastal disaster prevention and mitigation under extreme climate. Based on the Longuet-Higgins theory, the method of the field spectrum during the typhoon was used to compute the typhoon waves. And the directional spectrum, the formulas of wave surface, the velocity of water particles, and the acceleration of water particles were investigated. The results showed that the interpolated field wave spectrum combined with the SWOP direction spectrum could accurately simulate the three-dimensional typhoon waves. The significant wave height and the average period of the simulated wave surface at fixed point were statistically evaluated by the upward zero-crossing method, and the relative errors were ± 5% and ± 15%, respectively. The typhoon wave surface computed by a dual peak spectrum had small periodic waves, and the velocity and acceleration of water particles differed considerably from the JONSWAP spectrum. Finally, a fastened slender cylinder was simulated under action of the typhoon waves, which proved the applicability of the computation method. This study aims at providing a basis for the simulation of the dynamic response of marine structures under the typhoon waves action.