The Study On Characteristics Of Railway (Highway)Subgrade Scoured By Mountain Torrents And Evaluation Of Anti-erosion Level

In recent years, the phenomenon of railway (highway) subgrade scoured by mountain floods occurred frequently which caused serious damage and great loss to our society and brought a certain impact to normal management of the transportation operations. However, it is still not clear enough on erosion failure mechanism of the subgrade and there is no uniform prediction model on stability of them currently. In order to effectively develop and implement mitigation or prevention measures of flash floods disaster, it is necessary to approach to erosion failure mechanism, prediction model on subgrade stability and evaluation of anti-erosion level. It will be significant to perfect the railway (highway) design theory and hazard control measures. The main content and conclusions of the paper are as follows:(1) The paper analyzes the failure modes of every kinds of railway (highway) structure scored by floods and summarizes the reasons of subgrade erosion which include aspects of floods disaster, railway (highway) survey, design, construction, management of operations, which provides a theory basis for the factors selection of anti-erosion level evaluation.(2) To Propose that subgrade erosion have two kinds of failure modes:sliding failure and collapse damage and to improve mechanic analysis models under the two failure modes respectively, according to the main actions between floods and embankment—softening caused by water, scouring and erosion. Considering the aforementioned two modes, the formulas used to calculate stability of the subgrade scoured by floods have been derived.(3) In order to the solve the problem that a variety of scouring stability calculation model whose predicted results are inconsistent, it recommends using database and programming technology to statistic the accuracy of the embankment stability which is predicted by different kind of calculation models. Along with the continuous renewal of the database, it will help choose the best calculation model for a particular area of subgrade through comparing the models’prediction accuracy.(4) Based on binary comparison method and the grey system theory, it forms a kind of improved multi-objective fuzzy optimization model based on correlation-binary comparison analysis method that used to calculate subjective weight. Based on deviation minimization method, it takes advantage of subjective weights from correlation-binary comparison analysis method and objective weights from entropy method which is applied to risk evaluation of mountain torrent disaster.(5) Combined with erosion factors, failure mechanism of subgrade and based on characteristics of subgrade padding, it selects5first-level indexes from the factors of floods disaster, railway (highway) survey, design, construction, management of operations, which include14second-level indexes, to establish the evaluation index system of anti-erosion Ievel of subgrade engineering.