Study On Characteristics Of The Sutures Along Sichuan-Tibet Railway And Engineering Measures

There are three ophiolite sutures along Sichuan-Tibet railway:the south line would line orthogonal crossing Batang while the north line would line orthogonal crossing Dege-Jiangda,both of them are the parts of the ophiolite-bearing Longmucuo-Jinsha suture.The railway nearly obliquely will cross the ophiolite-bearing Bangongcuo-Nujiang suture.The line will along the ophiolite-bearing Yarlung Zangbo River suture for almost 400km.This paper describe the special landscape features of the suture area to get through the distribution of the ophiolite lots along the Sichuan-Tibet railway,which is also to make the qualitative and quantitative analysis of the dynamic activity within tectonic belts and theirs adjacent areas individually and correctly by using the seismic density value based on the theory of seismic energy-intense,and also by discussing the basic physical properties and doing engineering mechanics testing of the ophiolite rock samples collected from the specific areas-Yarlung Zangbo River suture to study the natures of the ophiolite.This purpose of the paper is to find some disaster prevention and reduction engineering and protective engineering measures through the intense studies of the above while the railway through the Qinghai-Tibet Plateau sutures.Tectonic earthquakes often occur in Tibetan tectonic zone.Based on the value of the theory of seismic energy intensive to use the existing records of historical earthquakes Tibetan Plateau,then by using seismic energy-intensive method of calculating the value of the Sichuan-Tibet line through the dynamic activity of the tectonic belt active degree were analyzed.We can get the conclusion that the dynamic activity within Yarlung Zangbo suture zone is less by using the above method to calculate the seismic density value among the active tectonic zones.So the dynamic activity within Brahmaputra suture zone does not belong to the controlling factor when the Sichuan-Tibet railway crossing the Yarlung Zangbo suture zone.The ophiolite sets complex and the properties of the rocks diverse.This paper selects the typical ophiolite rocks among the ophiolite to discuss the basic physical and do the mechanical experiments to have the following suggestions and comments on the Sichuan-Tibet railway project:where the green serpentinite are exposed to the surface in ophiolite suture zone while the line selection should be avoided;the slope excavation in the project should be sealed promptly to avoid the rocks' properties be weakened by the weathering where the peridotite and dunite are exposed to the surface in ophiolite suture zone;line project should actively exploit red siliceous rocks exposed to the surface as good geological conditions,but red chert rock is a kind of brittle rocks,maybe there is a phenomenon of the rockburst and rockfall in buried deep rock excavation slope;the line works take advantage of its high uniaxial compressive strength properties in ophiolite suture zone.The ophiolite sets mainly include peridotite,gabbro and some other mafic rocks.As the mount of green serpentinite after the serpentine of peridotite rocks is rare,so the content of green serpentinite isn't a controlling factor in line engineering.We know that the uniaxial compressive strength of peridotites and some other mafic rocks are fairly high and with considerable poor weathering resistance,so the slope should be sealed timely to after excavation.