Applied Mechanics and Materials Vols. 405-408

Abstract: The physical model of Jiaogang Ship Lock is established. Through model test, the flow condition in lock chamber and approach channel is studied. The results indicate when the upstream water level keeps high and the water level difference between upstream and downstream is less than 0.5 meter, the main flow oscillates less during spring tide flux and reflux in the flood year. When the upper water level is 0.96 m and during spring tide flux and reflux in the flood year, the flow is from downstream to upstream and the flow is smooth. When the upper water level is greater than lower water level, the sluice gate hoist condition is tidal range less than 0.3m in tide flux and less than 0.4m in tide reflux. Under the critical water level conditions, the Jiaogang Ship Lock sluice gate can be hoisted safely.

Abstract: To obtain a more detailed description of wave overtopping, a 2-D numerical wave tank is presented based on an open-source SPH platform named DualSPHysics, using a source generation and absorption technology suited for SPH methods with analytical relaxation approach. Numerical simulation of regular wave run-up and overtopping on typical sloping dikes is carried out and satisfactory agreements are shown between numerical results and experimental data. Another overtopping simulation of regular wave is conducted against six different types of seawalls (vertical wall, curved wall, recurved wall, 1:3 slope with smooth face, 1:1.5 slope with smooth face and 1:1.5 slope with stepped-face), which represents the details of various breaking waves interacting with different seawalls, and the average deviation of wave overtopping rate is 6.8%.

Abstract: A 2D numerical model about the Changjiang Estuary was set up with MIKE 21 in this study, which was well calibrated and verified with the observed tidal levels, flow velocities and flow directions, the computed results agree well with the measured data. Then the model has been applied to calculate the tidal level in the North Branch during spring and neap tide in flood season. The results show that, from the middle reach to the upper reach of the North Branch, the high tidal level is lower and lower and the low tidal level is upper and upper, so the tidal range is decreased, and tidal range during spring is greater than the one during neap. The tidal peak appearing time in the upper reach of the North Branch lags behind that of the middle reach, which is obviously during neap tide. The tidal level curve of the middle reach of the North Branch is smooth and close to the simple harmonic curve, while that of the upper reach of the North Branch deformities, the tidal level curve of ebb tide change fluctuant, much more obviously at spring tide.

Abstract: Sandbar is the main geomorphic unit in estuary, and due to the effects of runoff, tide and fresh-salt water mixing, the sediment movement there differs from others. Taking the Yangtze Estuary as an example, firstly, its sediment transport forms many circles both in longitudinal sections and transverse sections. Secondly, its sediment trapping is controlled by two different mechanisms, tidal current and salt water. The former contains the delay effect of sediment deposition and incipient motion, the asymmetry of flood and ebb, and the separation of flood and ebb, whereas the latter includes the influence of the saltwater wedge density current, the aggregation of the saltwater intrusion fronts, and the trapping of flocculation. Finally, its sediment re-suspension occurs three or four times ,not noly at the moment of flood or ebb maximumbut also at the transferring period from flood to ebb or from ebb to flood.

Abstract: Through simulating box girder with shell element, the influence of the top flangebottom flange and web thickness on the shear lag effect of box girder used in cable-stayed bridge was discussed on the background of Jianning bridge in Zhuzhou. Parameter analysis of the thickness change of the top flange, bottom flange and web on shear lag effect of box girder was based on analyzing and comparing the calculated results. The results show that the thickness change of the top flange, bottom flange and web have more influence on the shear lag effect of top flange than that of bottom flange; thickness increase of bottom flange and web can make the shear lag effect intensified obviously; and thickness change of web has the most significant influence on the shear lag effect among them for box girder with single box and three rooms used in cable-stayed bridges.

Abstract: In order to study the influence of the central buckle to the long-span suspension bridge structure mechanical characteristic, the Siduhe Bridge in Hubei Province was taken as the research background, the study were carried on the vibration characteristics, the driving comfort and the vehicle-bridge coupled vibration, which effected by the central buckle of the long-span suspension bridge. The results show that the central buckle has great impact on the large-span suspension bridge natural frequency, the central buckle can large extent increase the structure rigidity, improve the structure self-vibration frequency, and enhance the stability. The vehicle has good comfortable performance when droved on the bridge, and the central buckle has less effect on the comfortable quality. The central button setting can effectively reverse the lower stiffening girder displacement, and improve the stability of the bridge traffic.

Abstract: As a new long-span suspension bridge with double main spans and a typical closed streamline cross-section of single box deck, the flutter performance of the Maanshan Bridge during erection was investigated via a full bridge aeroelastic model test. Critical flutter wind speeds of 13 testing cases with different percentage of deck completion are much higher than the flutter checking wind speeds, and the bridge is hence proven to be stable enough during erection in aerodynamics. The case with the percentage of deck completion of 86.4% gets the lowest flutter critical wind speed, perhaps because frequency ratio gets the minimum value at this case.

Abstract: Combine the specific bridge, an analytical on the bridges static performance studied through the finite element model analysis and field test method. Summary and analyze the displacement and stress variation law of the main truss, longitudinal beams and beams which the bolt and weld superstructure steel truss bridges are effected by static loads, and compared field test results with theory value. Application practice proves that the evaluation standard and inspection of steel truss bridge is appropriate.

Abstract: In order to predict the effects on the hydrodynamic environment caused by the Hong Kong-Zhuhai-Macao Bridge, the physical model is built to analyze the changes of morphodynamic process. The experimental results show that the drag force on flow is increased and the flow section area is decreased by the two large artificial islands built in the sea. The opposite side of the artificial islands, there is the recirculation zone with many vortexes in different scales, which have the periodic change from formation to disappearance. Near both ends of the artificial islands, the velocities of tidal currents increase, then the seabed has obvious erosion trend. Affected by the topography, hydrodynamic conditions, as well as by the position, shape and scale of the artificial islands, the changes of morphodynamic process caused by both the west artificial island and the east one is similar in the change rules and different in the forms.

Abstract: To meet the requirements of construction convenience and protection level for concrete bridge barrier, this article researches the base form of detached and re-installed barriers. Considering integrity and dismounting convenience, four base forms were put forward such as anchor bolt connected base,outside embedded base, inside embedded base and steel bar welded base. The four base forms were compared through computer simulation, bogie test and analysis of construction convenience. The researches show that there are more probability for inside embedded base and outside embedded base to overturn in practical application. The anchor bolt is likely to cause stress concentration of connection location, and difficult to install. Rigid connection between barrier and bridge frange plate was formed by base steel welded with anchor plate, and so the integrity is better and the construction is convenient and feasible. And so steel bar welded base is the best and suitable for application in the project.