Applied Mechanics and Materials Vols. 204-208

Abstract: The existing design code of natural gas wharf appears to be rough for LNG channel width in the quantitative, and lacks of testing and risk evaluation. The outstanding problem is studied by relying on the study on navigation safety of Shandong LNG project. Taking a 360 meters LNG vessel as a simulation object, according to the local navigation condition designed of a condition scheme, the NT-PRO4000 type of ship maneuvering simulator is used to make a ship handling simulation experiment about the large LNG vessel, and the statistics of the ship track frequency is analyzed. Large LNG vessel’s acceptable risk standard is designed by introducing the concept of social general acceptable risk standard, to calculate the channel width design proposal based on the acceptable risk standard of large LNG vessel. Finally, the risk probabilities are evaluated about the design proposal and the original plan by grounding model, the economic channel width value in the same risk rate is obtained, and providing a new idea for the study of safety and economic channel width for LNG channel.

Abstract: The underwater performance deterioration of different mineral admixtures concrete was tested through the indoor immersion experiment. The effect and mechanism of fly ash and slag powder were studied after 360d’s immersion. The performance deterioration and internal structure changes were analyzed with chloride ion content, ultrasonic test, SEM scan and X-CT technology. The results showed that mineral admixtures can refine the pore structure and block the channel in the concrete. The mineral admixture (especially FA) can help to resist chloride penetration. The ultrasonic velocity of C50F and C50S increased first, and then decreased after 160d and 50d, respectively. After 360d’s corrosion, the porosity (holes with diameter greater than 30μm) of three samples all increased, but the shape of holes for mineral admixture concrete changed significantly. Among them, the adding of SL had greater effect on the porosity.

Abstract: The Parabolic mild slope equation and Boussinesq equation wave models are studied in this paper. First, the wave models Funwave and REF/DIF, which based on Boussinesq equations and the parabolic mild slope equation, respectively, are introduced. And then, two experiments are used to study these two wave models, one is the non-breaking shoal experiment of University of Delaware and the other is the breaking undertow test experiment, which was finished in Ocean University of China by author. Last, the simulation data of two wave models are compared with the measured data. The results show that both Boussinesq equation and the parabolic mild slope equation wave models can simulated nearshore wave condition precisely, but Boussinesq equation wave models has a disadvantage in catching the variation of wave height caused by wave breaking.

Abstract: According to the need of production and development, the coal unloading wharves of yihua harbor in the lower changjiang river need to be expanded and reconstructed. In the reconstruction, the main body can only be reinforced, not be dismounted, and the reconstruction project can not affect the unloading, so it is with great difficulty. The available plan of the reconstruction is researched and adopted. The inner force of crane girder and bridging beam is calculated by using the theory of elasticity support continuous beam. The piles are assigned with reason, the differential settlement between the new and the old building is nearly eliminated, and the bearing condition of the main structure is improved. So it is needless to carry through driving pile over water or subbottom reinforcing pile foundation under the cross frame of the former wharf . The key technology is boring a pile driving hole in added pile position on the wharf deck of the crane girder side, then to drive the precast piles through the hole on the deck of the wharf with the land vibrating pile driver. The strict restrict of driving piles on the water avoided, at the same time, the coal unloading is not affected. Pile driving on the wharf deck less difficult condition than that one on the water. The practice indicated that this methods is reliable. So it has great guidance meaning to the similar wharf reconstruction project, especially as some ones in which the bearing capacity of the piles can not meet the need under the cross bend frame.

Abstract: The appearance of the offshore constructions will affect the hydrodynamic environment greatly. The direct effect is the change of hydrodynamic environment, which will affect the silt migration path and cause local scour. So a local refined calculation model of tidal distribution is developed in this paper to study the tidal current distribution and sediment scouring and deposition around the offshore constructions. Then an artificial island at Shengli Oil filed is taken for example. The developed model above is adopted to simulate the tidal distribution and local scouring change before and after the construction of the artificial island. The results of calculation show that excessive flow velocity appears near the construction, which cause sever local scour. And the calculation results can also provide technical support for the safety evaluation of the offshore constructions.

Abstract: Since 2005, the increased quantity of back silting in the Deepwater Channel has a negative effect on shipping. This research sets up a 2D current model for the Changjiang River estuary using Delft3D-FLOW. The model is well calibrated and verified by applying the observed data of tidal levels and velocities, i.e. the water level, flow velocity magnitude and direction computed from the model agree well with the real measured data. In order to explore the influence of saltwater intrusion on the Deepwater Channel in the Changjiang Estuary, the computed velocity along the Deepwater Channel, the horizontal and longitudinal salinity distribution in the Deepwater Channel in the dry and wet season are analyzed. Analyzed results show that the fine suspended sediment flocculates easily in the upper reach of the Deepwater Channel beyond Hengsha Island in dry season, which increases sediment’s falling and deposition in this region.

Abstract: A multinest storm surge-wave-sediment model is applied to simulate strong storm surge caused by winter storm in Bohai Bay in Oct, 2003. The fields of current and sediment of for- and post- regulating structure are calculated to analysis the effect of regulation. The results show that the alongshore current caused by storm surge strengthen the cross-channel component and that provided the impetus conditions for sediment transport. The siltation in the outer channel of Huanghua port in the second stage is very severe. For example, the thickness of slitting sediment in the area, 3~19 kilometers (away from the entrance of port) is over 2.0 meters. While the third stage dike for debris barrier is completed, the hyper-concentrated silt-laden flow offshore could be eluded, and the maximum deposition area goes out thus the sediment siltation is reduced.

Abstract: Due to its special coastal soil condition and climatic and hydrological conditions, Wenzhou is prone to have landslides and other geologic hazards. According to the investigation about the soil and climate condition in Wenzhou and combining with the result of the survey, we analyzed the slope stability and concluded the main reason for how typhoon causes landslide in the coastal area of Wenzhou. Ultimately, we studied the suitable measures in dealing with slope protection and made a conclusion.

Abstract: A hydrodynamic model of Shijiu port and its adjacent sea area was built to discuss the effect of western the fourth phase project on the flow condition for Shijiu port area. The results show that with the sheltering effect of breakwaters, flow velocity values are small inside the breakwaters. The water area near the project is affected more by the project construction. The flow velocities there are faster after the project construction than before it. In the main channel, flow velocities outside the breakwaters almost have no difference before and after the project. The project construction doesn’t have significant effect on it.

Abstract: Four types of bank collapses in the middle-lower Yangtze River, that is erosion type, crash type, slippage type and flow-slide type, are pointed out, and characteristics and formation conditions of each one are analyzed. In order to provide a reference for decision-making of calamity reduction and improvement project, some preventive measures on them, including monitoring of river hydrology, morphology near bank, and hydrologicalgeology, and inspection and investigation of outward indication of bank and human activity, are presented by means of analysis on above-mentioned aspects.