Weigh-in-Motion System Study On Interaction Mechanism Between Flow Structures And Ships Around Piers

With the rapid development of the domestic economy, China’s demand for passengersand logistics increases. In recent years, due to its characteristics of large volume, low cost,energy conservation and environmental protection, waterway transport has gradually becomean integral part of the modern transport system. With both the main waterway traffic and theship type increase gradually, the requirements of the waterway is also rising, Based on thewaterway construction plans of the relevant departments, the future main waterway will beupgraded. In view of new circumstances of high-grade waterway and changed ship-type, howto define the ship navigation safe distance of bridge area is particularly important. But there isstill a certain degree of difficulty to deal with the new circumstances above with existedtechnology and related research. At present, experts and scholars home and abroad haveconducted a lot of studies on how the crossing-bridge constructions affect the navigationsafety. And it is an important issue to ensure the navigation safety on how to determine thesafe distance between ship and bridge and to pre-control the ship for not hitting the bridgefoundation. The research results of such issue can be grouped into the following twocategories. One is from the ship perspective, the research results of this category are all onhow the crossing bridges affect the ship motion and the ship hydrodynamics derivatives inorder to determine the ship domain and the critical runaway interference area. The other isfrom the navigation perspective, the research results of this category are all on how thecrossing bridges affect the navigation conditions in order to determine the piers turbulent area.Based on the single cylindrical pier and the inland river ship type, this paper mainlystudied the interaction mechanism between ships and the water structures around the piers.Using the combining methods of physical model and numerical simulation, the paper hadconducted research on the following aspects: the interaction evolution laws of ships and thewater structures around the piers; the sensitivity analysis on ship-bridge horizontal distance;the defined method of ship-bridge safe distance from the perspective of the ship yaw. And the paper had acquired the following conclusions. A. Both the increase of flow velocity betweenship and bridge and the negative pressure area occurred when the vortex comes close to theship that causes the ship’s yawing moment in the motion process.B. When the ship passes thepiers, the yawing moment often appears two positive peaks and at least one negative peak.The first positive peak appears when the ship bow is close to the pier. Then the negative peakappears and finally it reverses to the second positive peak. C. The horizontal distance, whichis over1.0D is considered as the ship-bridge safe distance.As the ship type, navigation condition and the pier type all change, ship-bridge safedistance is not the fixed value which needs to analyze the specific issues. So two definedmodels of ship-bridge safe distance are offered in this paper.The research results of this paper could not only offer suggestions to define theship-bridge safe distance, but also provide references on navigation and ships plan and design,pier anti-collision and ship maneuvering.