Study On Evaluation System Of Geological Hazard In Rock Slope Along Highway In Highly Seismic Region Based On Data Mining Technique

At14:28on May12th2008, a strong earthquake measuring8.0hit the Yingxiutown in Wenchuan County of Sichuan Province(N31.0°, E130.4°). It is a shallowearthquake, with the strongest intensity of Ⅺ degree and the depth of14km.Meanwhile, it is the most wide spread, damaging losses earthquake since thefoundation of the country, which induces a large number of secondary geologicalcalamities such as rock fall and landslide.In this paper, we take Wenchuan earthquake zone as example, and study theassessment system of geological hazard in rock slope along the highway in highlyseismic region. First, the geological environment conditions of the study area hasbeen detailed analyzed from the perspective of geological analysis, and theformation mechanism, development and distribution characteristics were discussedat the same time. On this basis, from the point of view of the development scale, thepaper grades the stability of the slop, establishes a assessment index system ofgeological hazard in rock slop by analyzing the internal and external factorscombined with attribute reduction algorithm in rough set theory, and determine thequantification rules of the evaluation index. Afterward, the paper establishes theevaluation decision tables of the surveyed geological hazard according to theevaluation index system, creates geological hazard assessment model based on thedecision tree classification algorithm in data mining techniques, optimizes theassessment model by citing integrated learning algorithm in machine learning.Finally, the paper analyzes the model’s evaluation effect with a practical example.Thereby, a complete geological hazard assessment system in rock slope along the highway in highly seismic region is established. The main results are as follows:(1) On the basis of previous research, the paper analyses the characteristic thatthe tensile failure is the main form of rock slope failure in earthquake conditions,according to the actual survey result of the geological disaster of seismic collapses,landslides in rock slope along the highway in the study area. Meanwhile, it detailedanalyses formation conditions and failure modes of the geological disasters indifferent type induced by Wenchuan earthquake.(2) Characteristics of the development scale of geological disaster of seismiccollapses, landslides in rock slope along the highway in the study area are analyzed.Thereinto, the number of geological disasters with development scale less than5000m3is about half of the total. It indicates that in all the seismic collapses,landslides disasters that occurred in the rock slope in the Wenchuan earthquakeregion, the small-scale disasters develop the most widely. Meanwhile, the Wenchuanearthquake triggered a large number of large-scale geological disasters. In theseismic collapses, landslides disasters surveyed, the number of which with thedevelopment scale over100000m3is about15%of the total, including somedisasters with the scale more than one million stere.(3) According to the statistics on the overall slope of the instable and failedrock slope, the slope of higher frequency of occurrence of the rock slope geologicalhazards is between40°and65°. And the statistics on the direction of the rock slopeshowed that the advantage direction which is conducive to the geological disasters isnot obvious, except the trend toward the north-west and NEE that is slightlyadvantage. Besides, in addition to the close link between the slope geologicaldisasters and the lithology and rock structure along the road in the seismic area, itsdevelopment also had the obvious hanging wall/footwall effect and distance effectof the fault zone.(4) On the basis of detailed analysis of internal factors and external factors ofgeological disasters in rock slope, combined with the specific characteristics ofgeological hazards in the study area,13factors are selected to establish thegeological disaster evaluation index system, and the dereferencing method and thegrade assessment criterion are detailed analysed for each evaluating indicator. Basedon this evaluation index system, the evaluating decision table of geological disastersin rock slope along the highway is created. Then, it is analysed by the attributereduction algorithm in rough set theory to get the attribute reduction set of theevaluating indicators of the geological disasters. According to this attribute reduction set and combined with the geological analysis, a new evaluation indexsystem is built to evaluate the geological disasters in rock slope in Wenchuanearthquake region more suitably. And the corresponding evaluating decision table iscreated at the same time.(5) Based on the decision tree theory, the assessment model of geologicalhazard in rock slope along the highway in highly seismic region is established. Andwith the usage of the ensemble learning method of bagging and adaboost integrationalgorithm, the integrated decision tree evaluation model is also established，based onthe decision tree evaluation model. Then the evaluation effect of different models isanalyzed with these field investigation instances in the study area, and the resultsindicated that the integrated decision tree evaluation model could achieve goodresults when it evaluated the geological hazard in rock slope in highly seismicregion. Besides, this evaluation model could be further optimized to improve theaccuracy of the evaluation so that it could further consummate the evaluationmethod of geological hazard in rock slope in highly seismic region.