Experimental Research On Mechanism And Protection Of Water Damage Of Small Bridges And Culverts In Mountainous Roads

As the main drainage facilities and the water outlet, the importance of the small bridges and culverts is obviously, especially in the drainage system of mountainous area road. Among the water damage of mountainous area road, that of small bridges and culverts costs a quite big percentage with various forms. It is necessary to analyze the mechanism of water damage of small bridges and culverts and propose efficient measures to protect the small bridges and culverts, aiming at improving the anti-water damage capacity of small bridges and culverts and their service level.Based on the introduction of common structure of small bridges and culverts and the reason for water damage of those in mountainous area, this paper made analysis of the formation mechanism of the local scour pit and established the relationship between scour depth and its factors, with the conclusion that the main factors are water power and soil property of riverbed.According to the analysis of the factors of local scour pit and the energy dissipated mechanism, consolidation tests of paves of small bridges and culverts and energy dissipation tests were conducted. And the conclusion is that lengthening the pave could alter the flow state and vertical distribution of the flow velocity, consequently decreasing the scour depth. However, the pave length is not unlimited because of the cost. Meanwhile, bucket could change the flow state of water and slow down the velocity of underflow, thereby the scour of the silt behind the droop skirt can be relieved through it.Through the comparison of different energy dissipation methods and numerical simulations, it can be found that the largest energy dissipation ratio is that of jet dissipaters, horizontal axe swirling flow has the least influence basin and flow velocity, with better flow state, it has well anti-scouring effect, which is better than three grade bucket and wave mode. Hopefully the decision-making ground could be proposed through this paper for the planning, design and maintenance of roads in mountainous area.