Influence Of Geological Hazard Risk And Engineering Geological Environment Quality On Transmission And Transformation Project Planning In Western Sichuan

This paper takes the western Sichuan area with abundant hydropower resources as the research object,and study on the impact of geological disasters and engineering geological environment quality on the planning of transmission and transformation projects.Based on the geological disaster and geological environment GIS database established in the earlier period,the research work was carried out.(1)The area of the study region is 33×10~4km~2,involving 11 cities(counties)and more than 70 counties(districts)in Western Sichuan.21897 geological disasters have been identified in the area.The main types are landslide,debris flow,collapse and unstable slope.The distribution characteristics,development laws and controlling factors of geological disasters have been systematically studied.The distribution characteristics of geological hazards are many in the East and South,less in the West and North.There are various types of geological hazards in the Longmen mountain fault area,and the scale is larger.Landslides prone to"red layer"and xigeda formation in the southern of Panxi area.The disasters in the western high plains are relatively weak and the scale is mainly small.(2)The power transmission and transformation engineering geological disasters can be divided into 4 types according to the inducing factor,the threat object and the influence range.(1)Threatening the substation and other large stations,which make the equipment damage,the base outage,the power supply interruption;(2)Geological disasters threaten the substation's access roads and other ancillary facilities,thus affecting the normal operation and maintenance of substations;(3)Geohazards damage transmission towers,resulting in interruption of lines.(4)Earthquake induced regional geological disasters,resulting in large regional power grids paralyzed.The disaster prevention and mitigation measures in the planning,construction,and maintenance are summarized.(3)Geological hazard susceptibility and risk assessment were carried out.In view of the distinct characteristics of landslides and debris flow,the research ideas of"first dividing and combining"are proposed.The risk of landslide and debris flow are evaluated based on different evaluation units and indexes,and comprehensive synthesis is carried out at last.The study of debris flow has a certain innovation,which is characterized by the introduction of the"D8"algorithm in hydrologic analysis to extract the basin units,carrying out the vulnerability and risk assessment of debris flow based on the basin unit,and further use the maximum accumulation fan width prediction formula to make the dangerous area from"the whole basin"Shrink to the ditch and gully near the mouth,achieving the mapping of dangerous area of debris flow.It provides a basis for the planning of power grid,the deployment of disaster prevention and mitigation work.The area of the Longmen mountain fault zone is generally in the"extremely dangerous zone"of geological disaster,the South Panxi area is"high risk",and the geological hazard in Ganzi and Aba state in the west is in the middle to low level.(4)From the professional angle of engineering geology,this paper makes a comprehensive analysis of many geological and engineering conditions that affect the construction of transmission and transformation project,puts forward the index system which is suitable for the quality evaluation of the geological environment in the study area,and makes use of the weighted fuzzy comprehensive evaluation method to evaluate the quality of the engineering geological environment.According to the characteristics of the site of the substation and transmission tower,the suitability of its construction land is analyzed.The research shows that the macroscopic influence of topography and fracture structure on engineering geological environment quality is more significant.The engineering geological environment of High altitude plain(such as Ruoergai and Hongyuan),rift basin(such as Yanyuan basin)and alluvial plain(such as the Anninghe River Valley)is relatively superior,the environmental quality of the deep valley and regional active fault zones is poor.(5)According to the macroscopic regional geological environment and traffic characteristics analysis of the potential power to send out the dominant channel.the comprehensive use of geological hazard and engineering geological environment quality research results,analysis of potential power out channel.Summing up the specific problems that need to be paid attention in the planning of transmission lines,,the paper puts forward the methods of line optimization and suggestions for disaster prevention and mitigation.The general guiding principles for planning,route selection and site selection are:we should give priority to the selection of paths and points with relatively less geological hazards,low risk and relatively good environmental quality.(1)The deep valley area:the substation and other large bases must pay attention to the safety of the site and the entrance road at the same time.The scientific planning and management of the construction land near the site is an effective means to ensure the safety and normal operation of the base.(2)In Panxi area,the landslides disaster in the"red layer",Xigeda formation and the steep slope farmland should be taken into consideration.Be care of the debris flow risk in the Piedmont valley plain boundary zone.The transmission line should be passed through the vertical fault zone as soon as possible to strengthen the protection of the tower foundation work.(3)The Longmen mountain fracture area:the disaster prevention and reduction work is a long way to go,a large number of"high position"hidden slope disasters have appeared in the mountain because of the loosening of the earthquake.The line planning and line selection should actively use remote sensing and UAV aerial photography to identify the hidden disaster points,and establish a scientific and effective disaster emergency disposal plan.The research results are of great significance to the understanding of the geological hazards and the characteristics of the engineering geological environment in Western Sichuan.It provides a basis for the planning of power transmission and Transformation Engineering in this area,the deployment of power grid system for disaster prevention and reduction.The research ideas and implementation methods of geological hazard risk and engineering geological environment have certain reference value for related research.