Wind & Wave Monitoring And Wave Forecasting For The Ocean Bridge

The sustained development of national highway and railway network and the steady implementation of a series of major strategic decisions, such as the national marine strategy, the Belt and Road initiative and the going global strategy of China high-speed railway, put forward strategic needs for the transportation infrastructure construction. As the control project of a line, Ocean Bridge has entered into a vigorous development period. This is an important development opportunity for the technological progress of China’s ocean bridge engineering, but it also faces a series of difficulties and challenges.The ocean bridge faces the harsh natural environment, such as gale, huge waves and rapids, during construction and operation.In addition to bear its own dead loads and live loads, it also bears huge wave-current force and wave impact force. Research shows that the wave-current force has become the control load of the ocean bridge. Obtaining accurate ocean environment elements such as wind and wave field in bridge site area is an important prerequisite for the calculation of wave-current force, however, during the design and construction of Ocean Bridge, the ocean environmental parameters such as wind and wave field in the bridge site area are always calculated by the ocean observation station nearby, and is different from the real parameters. Setting up an ocean environmental monitoring system of bridge site area is a fundamental work for the design and construction organization arrangement of Ocean Bridge and has very important theoretical significance and engineering value. Sea waves directly affect the construction safety, construction organization arrangement and the total project duration of the bridge. The prediction of sea wave height in the sea area of bridge site can provide reference for the construction organization arrangement of the bridge, and establish a safety early warning mechanism for the construction and operation of the bridge. It has important practical value and research significance.Based on the ocean environmental monitoring system of Pingtan Strait Railway-Highway Combined Bridge, this paper has researched on the new method of wind-wave statistics analysis and sea wave forecast. The main ideas and work have been listed below.(1) Characteristics of wind speed, wind direction and wave in the sea area of bridge site are obtained.(2) The gust factors in the sea area of bridge site both during typhoon period and not, and ratio coefficients between characteristic wave heights are calculated. The reasons of the differences between both the gust factor and the ratio coefficient and the given value in the relevant norms are analyzed.(3) The correlation among the wind velocities and the wave heights at different points in the sea area of the bridge site is analyzed, and the regression equation is obtained. The correlation of wind speed and wave height of 6# platform in the sea area of bridge site is analyzed, and the correlation formula of wind speed and wave height in winter is fitted.(4) The relationship between the performance of BP neural network and the number of hidden nodes and input training samples is studied. A BP neural network is established by using the wind speed, wind direction, wave height data of Minzhong sea area and measured wave height data of bridge site, to forecast 80 days wave heights in the sea area of bridge site, which obtains good prediction performance.