Comprehensive Assessment The Risk Of The Geological Disasters To Railway From Linzhi To Lhasa

The railway,running through the middle reaches of the Brahmaputra,which from linzhi to lhasa is the world's highest, most complex geological railway, which will be built in the Tibetan Plateau. Due to the complex geological structure ,active neotectionic movement ,alpine canyon lanform ,the railway from Jiacha to Langxian, created vaious and a great number of geohazards,mainly collapse,landslide and so on . The occurrence of those geohazards impact on the design and normal operation of railway transportation . Find out the characteristic, the distribution regularities along the railway become key engineering geological problems. Based on the collection of relevant reference and yield investigation.This paper the development characteristics and distribution of geological hazards were summed up. The forming conditions and affecting factors of geological hazards were analyzed.The secondary fuzzy comprehensive evaluation method was used to evaluate risk assessment of the geological disasters along the railway.(1)Through to studing the area the physical geography and the engineering geology environmental condition, summaries the development characteristics and distribution of geological hazards along the railway.Collapses are almost big and medium size ,distributed in hard rock strata such as granite. Landslide are almost medium size , distributed in soft rock strata ,such as phyllite and slate,with bedding band slope take a great number.Lengda and Longlan are the place where geological disasters distribute relatively dense,besides mainly distribute elevation between 3200 to 3600 meter, slope between 40 to 60 degree .The geological hazard were developed every May to September in time,when ice melt and the precipitation centralized . (2)In the study area ,the geological disaster is mianly controllty by geology structure, the structure of rock and soil type , faults, rainfall, earthquakes and human engineering activities.(3)In this paper ,we determine six geo-enviironmental factors in pregnancy disaster conditions such as the structure of rock and soil type, ground slope, relatively lithology, structure density, average rainfall, earthquake , vegetation coverage, human engineering activities, disaster density, size and harm object. the AHP was applied to assure the value of indexes, the method of fuzzy comprehensive judgement was utilized to evaluation the geohazard danger of the railway.(4)With the method of three-level fuzzy comprehensive judgement,according to the classification standard. Finally, the risk assessment zonation map was obtained though the analysis of result risk zonation of assessment unites which based on the principal of max degree of dcependence. The entire railway can be divided into six district, whichⅠarea andⅣarea are low- risk area,Ⅱarea andⅥarea are middle-risk area,Ⅲarea andⅤarea for high-risk area .(5)For the prevention and mitigation of geoharzads, what human being could utilize is mainly the space-difference and time-difference principle,adopting effective engineering countermeasures to avoid the loss of geohazards.