Investigation of Riprap and bridge pier upstream face shape as a countermeasure by SSIIM, Case study: Bahador-Abad bridge.

Riprap is a common method to protect bridge pier from scour due it performance and easy accecebilites and use. Riprap has always been a keen subject to river engineering and scouring researchers. In this study technical feasibility of Bahador-Abad bridge at Jiroft investigated for riprap-pier change shape countermeasure against scour. For the riprap term Richardson, Parola, Crod, Cheiw, Lachlan and Froehlich equations chose to predict the average diameters of riprap size in order to protect Bahador-Abad bridge piles. Although crod’s achieved the least scour depths but the other five find the riprap rock size (in order) 58.23, 58.23, 75.71, 71 and 63.83 percent less than Crod’s and they had resulted scour depth 16.54, 16.54, 40.6, 30.83 and 27.82 percent more than Crod’s. Froehlich equation declares as the best performance by 63.86% decrease in riprap size and 27.82% increase in scour depth. On the other hand, round nose and sharp nose were selected to pier upstream face. The SSIIM result, show that 27% and 35% decrease in scour depth respectively. At last, combine method simulated and tested as well. 56.28% and 62.37% scour depth decrease achieved. In zero angle attack condition, Riprap-sharp nose countermeasure advised.

Keywords:

Riprap , pier shape , countermeasure , SSIIM , Bahador-Abad bridge