ObjectiveThe guardrail is an important protection measure for the safety of highway traffic, but the single design can't adapt to various environments. With the practical activity in the sand area, it is found that banded sediment often appears in the sections of the guardrail. In view of this situation, on the basis of field investigation, from the perspective of aerodynamics, this study is to provide a solution for deposited sand in sandy region.
MethodTaking the highway guardrail as the research object, and reforming the guardrail with different porosity and orifice types, using wind tunnel simulation, Kriging interpolation and other methods, the impact of different guardrail on wind velocity flow field was analysed, and the impact of different types of guardrail on the absolute sediment concentration was calculated to select the appropriate configuration to achieve the purpose of preventing sand in the road.
ResultThe wind speed near the surface on the lee side of the traditional guardrail decreased to 80% of the original wind speed. Under the conditions of 5, 8 and 11 m/s, the absolute sediment concentration decreased by 44.7%, 64.8% and 75.1%, blocking effect of guardrail on wind sand flow is an important factor leading to the road sand. The new guardrail can improve the absolute sediment concentration of sand flow, and the effects of macropore and small hole guardrail on absolute sediment concentration had no obvious regularity with the porosity but lower than the initial level. The influence of strip on the absolute sediment concentration decreased with the increase of porosity. When the porosity reached 0.3, the absolute sediment concentration reached the initial level. In the near-surface layer with the highest sediment concentration in the wind-blown sand structure, the influence of different hole-type guardrails on the wind speed showed a consistent regularity, which decreased with the increase of the porosity. The stable wind speed at the leeward side of the macroreticular and the small fence was smaller than the initial wind speed under the condition of different porosities. The stability velocity of the strip guardrail with porosity of 0.3 and 0.4 reached the initial wind speed. From the wind speed flow field, at the leeward side of the traditional protection fence, obvious deceleration zone and low speed zone were formed along the wind direction, and the wind speed flow field structure of strip hole guardrail was more stable.
ConclusionThe guardrail with 0.3 and 0.4 porosities can improve the wind speed flow field and prevent sand accumulation in sandy region. In the future, research on guardrail should adapt to different driving environments based on safety standards so as to make full use of the guardrail.
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