Study On Comprehensive Risk Assessment And Early-Warning Of Geological Disasters For Shaan-Jing Pipeline

Shaan-Jing pipeline,crossing the frequency-occurring district of geological disasters,is the important lifeline which supplies gas to the regions of Beijing,Tianjin and Hebei.In order to reduce the losses caused by geological disasters,risk comprehensive assessment and monitoring and early-warning technology have been implemented on geological disasters in this paper,according to geological disaster types and distribution characteristics of Shaan-Jing pipeline.And then,corresponding prevention and control measurements are proposed.The detailed research work and achievements are shown as follows.(1)Types and characteristics of geological disaster along Shaan-Jing pipeline have been analyzed.The result shows that the most important factors which influence the safety of pipeline are landslide,collapse,debris flow and flood erosion and loess collapsibility,underground erosion and other unexpected geological disasters.And then,most geological disasters belong to slow degeneration are in the desert plateau,west of Bujiawa region.Appropriate protective measurements should be taken in engineering construction.However,in the loess plateau,north of Bujiawa,there are numerous types of geological disasters,which happen frequently and threat the pipeline.Besides,owing to the limitation of topography,it is difficult to choose the suitable laying route.Therefore,appropriate management measures must be taken in engineering construction.(2)Present situation and trend of geological disasters along Shaan-Jing pipeline is taken into account to classify different danger areas.Pipeline laied in Shaanxi region is studied in this section.According to characteristics of geological disasters and gas pipeline,risk of geological disasters that pipeline may suffer and possibilities that present dasaters deteriorate and new dsasters happen have been predicted.Finally,based on principles and methods of partition of geological disasters for pipelines,danger areas are determined.(3)Geological disasters in the region along Shaan-Jing pipeline are complex and diverse.According to these characteristics,a simplified risk assessment model is established and one ticket veto method of key risk factors is proposed.In another word,if the key risk factor happens,it should be considered as the highest risk rank without calculating risk value.Fault tree analysis(FTA)is adopted to qualitatively analyze risk factors of geological disaster along pipeline.And then,a risk assessment index system is established and 36 experienced experts are invited to give score according to the system.Finally,the index weight is calculated by interval judgement matrix and main risk factors are confirmed.(4)Two landslides and one mined-out area in research area are chosen as monitoring and early-warning objects.Designs of monitoring programs are researched by taking actual conditions of geological disaster site into account.Then nine professional monitoring equipments are installed and an integration prevention and control technology is realized.They are used to monitor displacement of rainfall in geological disaster site,displacement of landslide surface cracks and its deep displacement and crack width of mined-out area.The monitoring data is analyzed and some conclusions are obtained.One landslide is stable and under creep deformation stage.Another with a small deformation is still stable and wouldn't threat the pipeline.Crack width of the mined-out area is increasing and monitoring and touring should be strengthen.(5)Design and protection measurements for pipeline through geological disaster site are made by considering pipeline construction stage and disaster types,such as typical landslide,unstable slope,collapse,debris flow,karst collapse.A case study,which assesses the stability of the pipeline crossing a coal mine under three statuses of natural condition,trench excavation and pipe laid,turns out that pipeline construction had little effect on the mined-out area caused by coal production.The mined-out area and pipeline are very stable during pipeline construction and operation period.There is no need to take some prevent and control measurements.But they should be monitored all the time.What's more,in order to realies the automation of risk assessment and monitoring and early-warning,a consultation and expert management system has been developed,which plays an important and helpful role in promoting information management of geological disaster for Shaan-Jing pipeline.