| Water is one of the factors that have the greatest impact on the longevity of roads.Both groundwater and surface water pose a huge threat to the quality of roads.During precipitation,surface water that lands on the surface of the road will seep into the surface through joints,cracks,cracks or gaps in the road surface;At the same time,after rainwater falls,it will penetrate into the pavement structure through the central partition of the road,or when there is stagnant water on the dirt shoulder on both sides of the road.Water infiltration into the pavement will lead to the overall failure of the pavement and the reduction of the strength of the pavement structural layer,and diseases affecting the quality of the pavement will occur such as peeling,looseness,and potholes on the road surface.In addition,water entering the road surface can also cause road surface diseases such as mud and frost heave.The occurrence of these road diseases will have a serious impact on driving and threaten driving safety.It can be seen that it is precisely because the strength and stability of the roadbed pavement are so closely related to water,the correct and reasonable setting of anti-drainage facilities is an important factor in preventing roadbed pavement diseases,ensuring the quality of the pavement,and ensuring and extending the service life of the road.In this thesis,the drainage mode,drainage system and energy dissipation facilities of highway in Chongqing mountainous area are analyzed and studied,and the main conclusions are as follows:(1)The composition of the highway surface drainage system,the relevant design parameters of pavement surface drainage,the damage of rainwater and other water bodies to the drainage system were investigated,and the specific values of the design flow,rainfall intensity and confluence area were calculated through the analysis of the design flow,rainfall intensity and confluence area in line with the design and application of the road drainage system in Chongqing mountainous area.(2)This thesis proposes that the road can use dispersed diffuse drainage in mountainous steep slope areas with low road catchment and slow road slope,and calculate the water flow velocity at the foot of the downhill slope with different longitudinal slopes,embankment height,slope slope,and give corresponding anti-drainage facilities and measures.(3)In this thesis,the drainage ditches in the centralized drainage system are recommended for the steep slopes in the mountainous areas of Chongqing,the triangular drainage ditch with shallow groove and trapezoid drainage ditch with cover plate are recommended for the embankment slope with centralized drainage in Chongqing mountainous area,and the dish or semicircle drainage ditch is recommended for the cutting slope.At the same time,the capacity of the outlet is analyzed,and the required length of the outlet is calculated and compared by the empirical formula method and the theoretical analysis method.(4)By using FLUENT,the energy dissipation rate of step type,plunge pool and jet flow trough is calculated,and the influence of different factors on the energy dissipation rate is analyzed.The following suggestions are made for the energy dissipation facilities used in the centralized drainage of roads in Chongqing mountainous areas: 1.when the velocity of the drainage outlet is large,the velocity of the entrance of the jet stream trough is large,the stepped energy dissipation should be adopted.2.When the embankment height is high,the velocity at the end of the Jetstream trough may exceed the minimum velocity allowed by the Jetstream Trough to prevent erosion.3.When installing the energy dissipation tank at the bottom of the rapids,the energy dissipation tank of the rapids should be given priority.If the condition does not allow,may consider the plunge pool energy dissipation.4.when the height of embankment is high,even if the stepped energy dissipation is used,the velocity at the exit of the jet stream trough is still high. |
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