Adaptation Of Different Scales In The Same 3D Physical Model To Assess The Different Armour Sizes


  • D.P.L. RANASINGHE Specialist, Lanka Hydraulic Institute Ltd., Sri Lanka
  • K.P.M. FERNANDO Specialist, Lanka Hydraulic Institute Ltd., Sri Lanka
  • N.L. ENGILIYAGE Ph.D. Student, University of Maine, United States
  • J. K. P. KURUKULASURIYA Chief Executive Officer, Lanka Hydraulic Institute Ltd., Sri Lanka



3D physical model, Different prototype sizes, Different scales, Same model weights, Tetrapods Placement


While assessing the breakwater stability through a 3D physical model, the normal practice is to modify the structure element if the breakwater is unstable. However, casting a larger number of different sizes of concrete armour is time-consuming and costly. Therefore, the present study assessed the utilisation of the constructed model with 6.5T(1:41.37) to represent the 10.0T(1:47.82) and 12.5T(1:51.51) tetrapod (TTP) armours by using 88g TTP units in the model. Only the stability of the main armour at the roundhead was considered with new scales. Further, the same structure freeboard in the prototype was considered for new scales. Since the measured wave heights at the breakwater including the wave reflection from the structure, wave condition at the paddles were considered while selecting the input signals for the new scales during the trial runs. The selected inputs for the trail runs were verified with the post-calibration done for a 1:51.51 scale. Originally proposed 6.5T units were replaced by the hydraulically stable 12.5T units at the roundhead based on the model results done with different scales.




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