An experimental study on hydraulic stability of a homogenous partly/hardly reshaping double-berm breakwater Amir Mostaghiman amir.mostaghiman@gmail.com October 2020 Department of Civil Engineering Isfahan University of Technology, Isfahan 84156-83111, Iran Degree: M.Sc Language: Farsi Supervisor: Dr. Mohammad-Navid Moghim, moghim@iut.ac.ir The stability of rubble mound breakwaters, known as one of the prominent and most common structures protecting coastal areas, must be thoroughly evaluated to provide a stable and economic structure. To gain this goal, conducting a purposeful set of experiments and also a deep understanding of geometrical and environmental parameters affecting such structures need to be obtained. In the present study, a 2D experimental study of hardly/partly reshaping rubble mound mono and double-berm breakwaters subjected to irregular waves has been carried out. By exploiting the second berm and, subsequently, the changes made in the type of wave breaking from surging breaker into the plunging breaker, a more stable structure has been provided. Moreover, the presence of a second berm would restrict the run-up and run-down phenomena, which prevents the stones from corrosion and breaking in reshaping breakwaters and finally provides a more hardly/partly reshaping structure. The stability of a hardly/partly reshaping double-berm breakwater has been studied by delving into the effects of wave height, wave period, water depth, the first berm width, the first berm elevation from SWL, the second berm width, the second berm elevation from SWL and slope angle above the second berm on the eroded area made in the first berm. The findings reveal that as the wave height, the wave period, the water depth, the first berm elevation from SWL, and the second berm elevation from SWL increase, the eroded area made in the first berm increases, which consequently reduces the structure’s stability. On the other hand, by increasing the first berm width, the second berm width, and the slope angle over the second berm, the damage parameter would be declined. Additionally, in order to take the second berm characteristics such as berm width, berm elevation from SWL, and slope over the berm into account, an equivalent slope has been defined, which gives an equivalent Iribarren number for the structure in the presence of the second berm. Eventually, to provide applicable results, a new stability formula has been proposed for each breaking region. Keywords Double-berm breakwater, hardly/partly reshaping, experimental, hydraulic stability