Experimental Research On The Floating Transportation Hydrodynamics Of The Immersed Tube Tunnel Element

ABSTRACT:The the floating transportation of the Immersed tube tunnel (ITT) element is a very necessary process in the construction of the tube tunnel. Generally speaking, the ITT element is usually a rectangular box structure, with equidistribution of mass along the length direction, and the sectional size and the volume of it is huge. In the process of floating, the ITT element is affected by the speed of the river flow velocity and the flowing over a body, and it will suffer drag force, cross force and the corresponding moment of force. Because of the limit of the river channal and the huge volume and mass of the ITT element, it is very hard to manipulate the floating process of the ITT element and the manipulation is hysteretic. If the floating is out of balance, the ITT element will turn over and it will result in failure in the construction. Therefore, it is necessary to analyze the hydrodynamics of the ITT element in the process of the floating traspotation.Hydrodynamic model experiment is a very important method in the analysis of the hydrodynamics. Do the experiments of the scale model first, then converse the results of the experiment to the prototype of the ITT element and obtain the law of the forces, so that we can choose the construction factors correctly and provide the preference data for establishing the construction technology. Therefore, in this article, fisrst, I write the theoretical analysis of the floating transportation hydrodynamics of the ITT element containg the hydrodynamic analysis and the similarity analysis; then, through the experiment, we obtain the law between the factors like drag fore, tugging speed, river flow speed(modeled by the longitudinal tugging experiment), the type of the ITT element(constant cross-section and variable cross-section), etc; at last, we converse the results data to the prototype, so that we can provide the preference for establishing the construction technology and implementing the construction of the ZhouTouZui ITT in the city of GuangZhou.The model experiment shows that:the tugging speed is higher, the drag force is higher, in the case of being constant of the water depth, the draft, the heading angle and the wave factors; the wave is higher, the drag force is higher, in the case of being constant of the water depth, the draft, the heading angle and the tugging speed; the water depth is lower, the drag force is higher, in the case of being constant of the draft, the heading angle, the tugging speed and the wave factors; for the variable cross-section ITT element, the drag fore of bigger cross section being the incident flow section is higher than the smaller cross section being the incident flow section; in general, the drag force of the variable cross-section ITT element is higher than the constant cross-section ITT element.On the basis of the results of the model experiment, we converse the results of the experiment to the prototype, and make figers and tables to show the law of the experiment. The law shows that:the drag force of the two types of cross-section ITT elements and the tugging speed are well fitted with conic curve respectively; for the variable cross-setion ITT element, the drag force of the two types of incident flow section and the tugging speed are well fitted with conic curve respectively, and the drag force is higher of the bigger cross section being the incident flow section; when the heading angle is90degrees, the difference of the drag force between the variable cross-section and constant cross-section is small, and the drag force and the tugging speed is also well fitted with conic curve respectively; when there are waves, either constant cross-section or variable cross-section ITT element, the difference of both their max drag force and min drag force between the two types of ITT elements is big.In addition, under certain conditions, the results of coversing the model to the prototype are well coincident and fitted with the calculation results on the basis of the hydronamic calculation formula in the Specification for the Load in the Port Engineering. In the last of this article, the current force and the drag force of the prototype of the ITT element are given.Total:150figures,145tables,50references.