Study On The Risk Evaluation Of Rainfall Hazard On Highway Slope

There were too many roadside slope damages, which caused highway traffic and social economy influenced, during flood seasons year by year. In order to decrease loss in storm rainfall disaster, farther measures must be taken in road design, construction and maintain management to keep a lower level of the risk. The thesis has studied highway side slope rainfall erosion and rainfall instability disaster. The processes have been described from rainfall hazard, vulnerability of the objects at risk and loss or risks in side slope disaster. The assessment system was made up of a site, a highway and a highway net assessment.In the hazard evaluation process, concepts of frequency and efficient precipitation were introduced to exhibit the rainfall hazard of erosion and instability. Object vulnerability in erosion disaster was evaluated with some revised models based on soil erosion study in conservation field, while in instability disaster it was analyzed with reliability theory. Certainly a few simple methods were brought out in the dissertation. After all, risk assessment and loss evaluation of slope disaster caused by rainfall was discussed in chapter six and seven.At the first, drainage system was analyzed in its structure and functions. The system can be divided to series of subsystems which slope drainage is included. It was point out the slope drainage system is a net system composed of longitudinal and latitudinal ditches that play different roles. A new classification of rainfall disaster of highway is put forward by environment, key factor and object at risk. The dissertation discussed a practical grade classification according to investigated data of highway disaster in SICHUAN and SHAANXI province. The grade is distinguished with the current ones.Rainfall is the most important factor in slope disaster in which highway traffic is object at risk, and slope is a part of it. The hazard means rainfall hazard other than landslide hazard. When discuss hazard, the rainfall erosion intense was used to show the intense of slope scour, and the efficient former precipitation to show the cause of slope instability. The two indexes are related to highway engineering, and they wereconnected to disaster grade classify.To study the vulnerability of roadside slope, the dissertation discussed each parameter in the erosion model. For an example, the erodibility of compacted soil was studied with a soil disintegration instrument developed by the author. After the experience it was pointed out that the disintegrating rate represented soil erodibility. Meanwhile, the exiting drainage and protection was considered in the erosion calculation model according to field investigation. Even though the reliability theory was employed to induct the probability of slope instability, how rainfall made slope slip or slide was still a problem. The seep changes rock or earth in physical and mechanical parameters which were utilized in reliability estimate. The landslide scale in highway can be estimated with weak layers in rock or column method. There was also a practice way to size-up slope slide and influence scope on pavement.Rainfall slope hazard risk, which was classified five grades, was equal to the loss multiplying its probability. The dissertation had analyzed the risk with several ways. The benefit of slope drainage and protection from preventing disaster was estimated in technique and economy. It was composed of basic, economical and environmental benefit.In a word, the dissertation tried to express a new hazard risk management in highway. The author expects that it can be a help in traffic disaster prevention.