Emergency Mechanism And Integration Methods Of Risk Assessment For Ship-Bridge Collision In The Yangtze River

he safety passage of vessels under bridges becomes a key issue in the Yangtze River with more and more bridges coming up as well as the booming shipping industry. As for ship-bridge collision risk, it is necessary to study the complex causing mechanism and integration methods of risk assessment from different angles. So far, the collision probability modeling and impact calculation are two main directions in Ship-bridge collision (SBC) research field. All in all, the current research focus on passive study on the rule-based bridge clearance design and pier collide prevention. Recently, risk-based design comes to this field. Thus, ship-bridge emergency event is chosen as a research object by this paper, which aims to find the complex causing mechanism and risk assessment methods from an active prevention point of view. In this research, the theory and methodologies of science of complex are applied, such as accident causing theory, AHP methodology and integration theory.First of all, concept and structure of Complex system of "Human- Ship-Channel-Management (HSCM)" is put forward as well as defined by this dissertation based on Yangtze River situation. It set up a simplified HSCM system based on systematic safety. Secondly, it defined key elements of HSCM system and characters of ship across bridge, which integrated a lot of analyzing result of similar researches.A three-dimensional orbit intersecting Causes-Results Theory is promoted to explain the risk identification system. In accordance with Systematic Engineering Theory, risk elements is utilized to illuminate mechanism of SBC with single-factors, double factors and three-dimensional factors Causes-Results Theory by combining ship drifting theory, which extend the ship deviation theory.With Hierarchal Holographic Modeling (HHM) method, the SBC causing HHM is set up in accordance with a navigational risk resource data of Yangtze River for the further research. The HSCM system is a typical brittle system. By defining the brittleness source and system structure, the fault tree is used to identify the causing factors. Then a systematic brittleness assessment is studied by using FAHP method with the survey data of Sutong Yangtze Bridge.The ship traffic flow is one of the fundamental causing factors of SBC. As for ship arriving principal, a Poisson distribution is proved by the Jingzhou Yangtze bridge ship traffic data observation. The pier of bridge is considered as a relative static ship and therefore a simplified ship's avoiding collision model is set up based on priority level. By using computer simulation, an active ship passing bridge channel is demonstrated under the ship traffic flow management. In this case, a straight-channel SBC probability modeling is brought out with a ship-ship impact distribution.Method integration is applied on the bridge navigable assessment on risk-based design aspect. Bridge clearance is a key brittleness factor, therefore, a combination method such as rule-based design; drifting calculation and navigation simulation are put into use in the Wuhan Yingwuzhou Yangtze Bridge navigable risk assessment. As for various channel, it is necessary to verify the effectiveness and applicability of methods.