Study On The Risk Evaluation Of Rainfall Drainage System Of Mountainous Highway

Annually many rainfall disasters influenced on highway transportations and social economy during rain seasons in China. In order to decrease these rainfall disasters losses, a comprehensive strategic active precaution has been taken in process of highway designing, constructing, conserving and administrating. The effective mountainous highway drainage system is the key step among the various preventive calamity measures, which fleetly let the collected rainfall off the highway territory along the solidified drainage ditches. This paper has studied on how to prevent disasters from the highway drainage system ditches.At first, this paper has carried out a large number of field research and survey to some highway drainage destroyed problems. Through summarizing the mountainous highway drainage correct designing methods, and why and when and where the dilapidated ditches facilities easily taken place, and four typical damages ,this paper found that there were three hinge hydraulics problems which had to be tested to prevent the ditches to be collapsed in the expressway catchments system. These three problems are respectively the hydraulic characteristics and the scouring hole maximal depth of flow freely coming out of little bridge and culvert, the scouring hole depths of the flow coming out from the anxious launder groovy end, the rainfall erosive density of the compressed soil sloping face. After three experiments, this paper has obtained that the extreme velocity of the free flow from the little bridge and culvert, and the erosive maximum depths changing regular pattern behind the various eradicative energy moulds by laying concrete or stones, and the scouring hole maximal depth regular pattern of the flow coming out from the back of rapid stream groovy after the multifarious eradicative energy construction by laying stones, and the erosive intensity experiential formula of the impact loess sloping field under the rainfall and the various engineering conditions. These results provided a reasonable reference and consult for the drain-ditches design in cutting down the primary paramount frequency three drainage damages (little bridge culvert, rapid stream chamfer, intercept rainfall flowing ditch).Basing on the great number of the damaged points investigation and three crux hydraulics problems testing results, this paper has carried out four aspects of researches, which are the highway drainage facilities calamity breeding environments, the ditch calamity bearing ability, the decreasing calamity economy budget and benefit of prevention engineering measure. This paper has established the...