Experimental Study on Hydrodynamic Load Characteristics for A Typical Cross-Section of A Submerged Floating Tunnel

The typical cross-sectional form of a submerged floating tunnel plays a significant role in the dynamic response of the tunnel itself, which directly affects the overall design. In this work, a series of experiments involving wave action on a submerged floating tube cross section is reported to study its hydrodynamic load characteristics. Two typical cross section tube cylinders, circular and rectangular, are chosen. Experiments are carried out in a wave flume with waves of relatively low Keulegan-Carpenter (KC) numbers. Three relative depths of submergence of 0, 0.25 and 0.5 are chosen. The measured wave forces in regular waves are used to analyze the horizontal force, vertical force and torque, and then the drag coefficient (Cd) and inertia coefficient (Cm) are derived. The results show that the drag coefficients at low KC numbers are large and decrease sharply with increasing KC number. The inertial coefficient Cm values in the vertical direction are about 70% larger than those in the horizontal direction. With an increase in aspect ratio (the ratio of the height to width of the structure), the ratio of inertia coefficient in the horizontal direction to that in the vertical direction increases remarkably. The inertia force coefficient is very sensitive to the submerged water depth and aspect ratio. The existing results may overestimate the actual force value.