Research On The Reliability Of Urban Road Based On The Risk Assessment Of Secondary Geological Disaster

China is between the two major earthquake belts in the word and the earthquake disasters occur frequently.According to the earthquake disaster statistics over the year,forty-five percent cities are located in the high risk areas that the seismic intensity is not less than seven degrees.So,the earthquake is becoming the primary disaster that results in the huge loss in cites.However,in mountainous cities,the geological conditions are complex.when the earthquake happened,the secondary geological hazards will be triggered.Then there will be many serious chain reaction.The concentrated distribution of urban space,the various forms of economic diversity and more population are the reasons that result in the huge population casualties and the economic of the city.Therefore,it is important for us to research the risk assessment of secondary geological hazard.The urban road system is an important guarantee when we carry out emergency relief work and ensure the affected people's life and property safety after the earthquake.As soon as,it is the important "lifeline" for affected people.The patience of shock evacuation channel will directly influences the development of rescue work timely and smooth.At the same time,the timeliness of disaster relief work decide on the casualties and economic losses after the earthquake.So,it is very important to research the connectivity and reliability of urban roads after the earthquake.Based on this situation in our country and the theory of risk assessment of secondary geological hazard,this article makes a the field investigation in Yiliang.By analyzing the impact of the bridge and the collapse of the building on the capacity of the urban road system after the earthquake,this article finds the reliability of the road.There are the following specific research:First of all,this article assess the secondary geological hazard risk in Yiliang by using the tool of ArcGIS and the method of AHP.Based on the literature,the author summarizes the ten evaluation factors of the secondary geological hazard risk assessment.These evaluation factors include the triggering factor and the basic factor.By constructing the hierarchical structure of the analytic hierarchy process and the expert scores,the weight value of each influence factor was obtained.In the study area,the unified evaluation index of secondary geological hazard risk was established.By using the spatial analysis module of ArcGIS,the evaluation function of each evaluation index was carried out.Secondly,based on the evaluation of the secondary geological hazard risk,this article considers the influence of the post-earthquake bridge and the collapse of the street building and Secondary geological hazard area on the capacity of the urban road system.Through the rubble blockage model and the bridge earthquake damage model,to obtain the reliability of the road system.This study draws the following conclusions:(1)The study area is divided into four grades:The study area is divided into four grades:low risk zone,middle risk zone,middle high risk zone and high risk zone.The proportion of each grade risk area is 26.93 percent,36.05 percent,24.9 percent and 12.1 percent and the secondary geological hazard risk grade of Yiliang County belongs to the high risk area.The high risk area of the secondary geological hazard in the study area is mainly distributed on both sides of the Luoze River,the Xiaohe River and the Millet River Basin and the main road,which is mainly affected by the erosion of the river and the significant impact of the large human engineering activities and Low vegetation coverage rate.The evacuation routes of the study area are mostly distributed in high risk areas and the areas of middle high risk.When the earthquakes occur,the road are more likely to be affected by secondary geological disasters.(2)Without considering the earthquake secondary geological disasters in Yiliang County,Yiliang County in the fortification intensity of 7 degrees,Yiliang County urban road traffic system is basically reliable,basically to meet the evacuation of the staff after the earthquake,the wounded and disaster relief supplies and other transportation requirements.(3)When considering the secondary geological disasters of the earthquake,the reliability of the Yiliang county road traffic system is reduced rapidly.To achieve reliable link means substantially only 41%and unreliable sections account for 59%of the entire road segment.The entire city traffic network has basically been basically in a state of collapse.Some roads are blocked lurking dangers and,the surrounding road network of some Areais basically in basic unreliable,forming an island city in the state,it will lead to the outside world and rescue vehicles can not reach those affected,increasing the post-earthquake relief work Difficulty.