Investigation and Research on Improvement Measures of Drainage System of Wide Expressway
With the aim to improve the road capacity,reconstruction and extension of expressways have been implemented in numerous provinces in China.At present,most of the expressways have been changed from two-way four-lane to eight-lane or from six-lane to ten-lane.As a result of the project,the breadth of road will be apparently increased and the path of rainwater out of the road will be significantly extended,which will easily cause poor drainage on the surface of the superelevation gentle slope section,concave vertical curve bottom and interchange confluence ultra-wide section,which will seriously affect driving safety.By investigating the drainage situation of a number of reconstructed and extended expressways in Guangdong Province,the following improvements should be adopted for those sections with poor drainage.Firstly,rework or lengthen the longitudinal drainage ditches of the ultra-high section.Increase the diameter and tighten the spacing of the horizontal drainage pipes connected to it.Secondly,use both flush curb and longitudinal drainage ditches to perform the reconstruction of side drainage for the filled embankment sections with poor drainage.Thirdly,add drainage asphalt pavement and the top surface of the flush curb should be consistent with the bottom level of the drainage asphalt surface.Use hollow cover comb-shaped rectangular longitudinal drainage ditch at the separator of the ultra-high section,which is convenient for the rapid discharge of surface water and infiltration water on the pavement.Fourthly,add transverse gap drainage ditches on both sides of the bottom of the concave vertical curve.Add longitudinal gap drainage ditches in the intersection flow triangle area.At the same time,it has been necessary to strengthen the drainage design of concrete guardrail sections.Fifthly,for the widening of the bridge deck,set up longitudinal rectangular open ditches at the edge of the deck on the catchment side.And increase the diameter and tighten the spacing of the vertical drainage pipes appropriately to improve the drainage efficiency of the bridge deck.
heavy rainfall areaswide expresswaydrainage systemimprovement measures
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