Applied Mechanics and Materials Vols. 353-356

Abstract: According to the geological conditions and operating regimes of Wang river groundwater reservoir of Laizhou in Shandong, through doing sandy one-dimensional equal amplitude circulating compression test, the effect of groundwater level repeated rising or falling on volumes of groundwater reservoir is simulated, the character of porosity changing regulation with circulating period is analyzed, the relation between reduction rate of porosity and circulating period is summarized, and the hyperbolic model of reduction rate of porosity and circulating period is constructed initially, the concept of limiting reduction rate of porosity is proposed, the physical meaning of limiting reduction rate of porosity is analyzed, modifying volumes of groundwater reservoir by limiting reduction rate of porosity is used to reflect the effect of groundwater level repeated lifting on the capacity of groundwater reservoir.

Abstract: Sand waves are rhythmic patterns resulted from the interaction between water flow and sandy bed. In this paper the research progress upon the sand wave is introduced from three aspects which include theoretical analysis, numerical simulation and experimental study, based on the available literatures.

Abstract: Typhoon-induced water level in response to different typhoon tracks in Haizhou bay was investigated by the tidal data from 1997 to 2007. Results of the study show that typhoon passing over Haizhou bay can be divided into three classes according to their tracks. Under different tracks of typhoon, the typhoon-induced water level varies with the magnitude and duration. The non-tidal water level increase significant during class I and class II tracks, while the typhoon-induced water level during class III is less regular with relatively uniform amplitude. The duration of the typhoon-induced water level of class III is the longest among the three types.

Abstract: In order to design an effective and economical multi-point mooring system for the new concept FPSO IQFP (fillet inverted quadrangular frustum pyramid shaped FPSO, presented by the lead author), the effects of the mooring parameters on the performance of catenary mooring system and taut mooring system were investigated according to the initial design plans given in advance according to the steady environment forces and practical experiences. Then, the optimal mooring systems were developed on the basis of the static analysis results combined with the coupled calculations in time domain. Finally, the merits and demerits of the two mooring schemes were compared based on the mooring and static characteristic parameters as well as the curves of restoring force against horizontal displacement of the catenary and taut mooring systems respectively. The results verify that the taut mooring system is preferable to the catenary mooring system for IQFP deployed in shallow waters.

Abstract: The performance of absorbing boundary conditions in SWASH is examined. The method to determine the sponge layer region in each processor when calculating with multiple processors is improved. An exponential decay function is employed to the momentum equations in the sponge layer region. The numerical tests show that the proposed damping coefficients work efficiently on reducing the wave energy of reflective waves in the sponge layer.

Abstract: Saltwater intrusion is a serious problem for most of macro-tidal estuaries, especially when it happened at the downstream region of drinking water sources. Therefore, accurate prediction of salinity variation becomes absolutely necessary. A three-layer salinity prediction model is established in this paper, based on wavelet neural network (WNN) optimized by particle swarm optimization (PSO). The optimized model overcomes the local minimum problem and accelerates the convergence speed of WNN method. Hourly observed salinity data at Ganpu station in Qiantang Estuary was used for case study. Additionally, we compare this model with another two models, WNN and BP, by predicting the salinity at Ganpu station with the same sample. The results show that PSO-WNN model has higher convergence rate and prediction accuracy.

Abstract: The dynamic responses of single wharf slab and whole high-pile wharf structure is studied in modal analysis by 3D finite element model using software ABAQUS. According to the static force calculation module and the transient dynamics module of the ABAQUS finite element calculation, the displacement of wharf slab central point is calculated according to the effects of static force, slow variation, and the uplift pressure from both the shock and composite wave. Then the effects of wave force frequency impacting on the structure dynamic response is researched by the different high-frequency waves. These analysis results provide scientific basis and technical guidance for the high-pile wharf dynamic research in port engineering.

Abstract: Elastocoast revetment is a new slope protection structures. It has good frost heave adaptability. But it also suffers wave action when used for revetment works. In order to study its protective effect on bank slope, the Elastocoast revetments wave model test under wave action is made, and the cement mortar revetment comparative trail is made simultaneously. It is researched that the rule of wave reflectivity, wave run-up, bottom uplift and surface wave pressure. That offers theoretical basis and reference for structure design and guidance for engineering practice.

Abstract: In this study, an empirical curve describing the relation between erosion and deposition rate and water/sediment discharge was developed based on the recent evolution trend of the submerged delta at the Yangtze River Mouth, and the one-dimensional mathematical model for unsteady water-and sediment-transport was calibrated using the water and sediment discharge data after water impounding to predict the water and sediment discharge for the future 10 years and the future evolution of the submerged delta at the Yangtze River Mouth. The results showed that the 10 m and 20 m isobaths areas of the submerged delta changed with the water and sediment discharge from siltation to siltation slowing down to erosion. Siltation increased with large amount of rain received by the watershed during 1997-2000, while continuous retreat of erosion happened during 2000-2009. Using the one-dimensional mathematical model for river water and sediment calibrated and tested with data collected after impounding, the water and sediment discharges were calculated for Series 60 and 90, and its evolution in 2013-2022 was predicted for the delta. For Series 60, its 10 cm and 20 cm isobaths areas showed alternative scour and siltation, while the delta showed trends of erosion. For Series 90, its 10 m and 20 m isobaths showed substantial siltation in flood years. The water and sediment discharges since the Three Gorges Reservoirs was filled were lower than the calculated results for both Series 60 and 90. If the water and sediment discharges continue to decease, the delta will take an erosion trend.

Abstract: This paper studies uplift force on upper-structure of offshore high-pile wharf under interaction of wave and current through indoor wave physical model test. The research takes various wave elements, wave incident angle and the angle of wave and current and other factors into consideration and launches a series of test to analyze the influence of different factors on wave uplift force. The research result shows that with the increase of wave incident angle the wave action width decreases which results in the gradually decrease of wave uplift force. When wave and current are in the same direction, the total wave uplift force decrease; when wave and current are in opposite directions which leads to the reduce of wave incident angle while results in the increase of wave height, the total wave uplift force increases; when wave obliquely incidents with the action of current, the factors influencing uplift force consist of wave obliquely incident action and current.