| With the implementation of the national "13th Five-Year Plan" strategy,transportation infrastructure construction projects have gradually increased in order to build a complete highway network.Many of the roads proposed or under construction belong to mountainous roads,and face more complex geographical environment.During the construction period,a large number of high and steep cutting slopes have been formed along the road,which poses a great risk to the road construction.Therefore,it is especially important to study the identification method of high and steep slopes’ risk sources and establish a reasonable high and steep slope risk assessment index system for reducing the construction risk of mountainous roads.In this paper,the advantages and disadvantages of various risk assessment methods are comparatively analyzed and the risk assessment methods used in high and steep slopes are sorted out.Based on the AHP method,a continuous data discrete method,rough set theory,and orthogonal design analysis method,a comprehensive risk assessment method of high and steep slopes is recommended in this paper.Supported by the national key research and development plan subproject "Dangerous Source Identification and Risk Assessment of Large and Complex Tunnels and High and Steep Slopes"(2016YFC0802201-2),the main contents are as follows:1)According to the investigation of slopes materials along mountainous roads,a risk database of slope,including 131 rock slopes and 64 soil slopes,is established.Through analyzing database,on-the-spot investigation and searching relevant literatures,a threelevel index system of the risk assessment system for high and steep rock slopes and soil slopes was initially established,which provides basis for the selection of main control factors of slope risk assessment.2)The method of equal probability continuous data discrete was proposed and compared with that of equal width discrete.The k NN classification program was written by MATLAB to obtain the prediction accuracy of two discrete methods,the results showed that the former had higher prediction accuracy than that of the latter.This method,which improved the accuracy of the rough set theory attribute reduction algorithm,was determined as the main sort of processing sample data.3)Using the genetic algorithm-based attribute reduction algorithm in the rough set theory attribute reduction algorithm,the factors in the preliminary risk assessment indicators of high and steep rock slopes and soil slopes were screened.The main controlling factors of risk assessment for high and steep rock slope are slope height,slope gradient,cohesion,angle of internal friction,slope structure,and maximum daily rainfall,while the main controlling factors of risk assessment for high and steep soil slopes are slope height,slope gradient,cohesion,angle of internal friction,and maximum daily rainfall.It lays the foundation for establishing a complete index system of high and steep slope.4)The slope model was built by combining of orthogonal design method and Midas GTS NX software.Using the method of the range calculation and Contribution rate analysis method,the calculation results of the model were analyzed,and the importance order of each main control factor was determined.According to the improvement of contribution rate method,the weights of each main control factor were obtain,and a complete risk assessment index system of high and steep rock slopes and soil slopes was established.5)Based on the Visual Studio 2013 platform and C #,a software system of risk assessment for high-steep slope,which named " HASSRASS 1.0",was developed for this indicator system.This software system was applied in actual engineering to improve the efficiency of slope risk assessment.Taking a high-steep slope project in Yunyang County,Chongqing as an example,the risk assessment method for high-steep slope was fully applied,and at the same time,risk prevention measures were proposed for the project. |
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