Research On Thermal Stability Of Railway Roadbed In The Permafrost Area Of The Qinghai-Tibet Plateau

The stability of railway roadbed is an essential problem when researching railway construction technique in permafrost area of the plateau.The soil temperature has effects on the stability of railway roadbed in terms of strength,deformation genesis and degradation of the permafrost.When evaluating stability of railway roadbed in the permafrost area , its thermo-stability should be firstly evaluated,then it carries on evaluating the thermo-stability of roadbed base and slope in the permafrost after the roadbed is constructed. Based on the investigation and analysis on weather change in the permafrost area of the plateau and global weather change,especially the characteristics and trend of weather change in railway permafrost area of the plateau , the author discusses characteristics and trend of weather change in typical section of railway permafrost area of the plateau,and discusses the engineering geology condition change of froze soil while ground temperature changes,in the same time,the author followed up with all change effected on railway roadbed.Based on these research,some method of developed roadbed thermal stability and conclusion used for designer and constructer were provided. In first chapter,the concept of roadbed thermal stability was provided,also important meaning studying this problem in process of construction Qinghai-Tibet railway was discussed. In second chapter,weather change of railway permafrost area of the plateau was studied.for a long time thirty-year,the trend of weather change has gone up ,the ascending value is about 0.45 centigrade. In third chapter , soil temperature sub-region and the change of engineering geology condition in plateau were discussed.With mean annual air temperature changes,ground temperature changed also.If air temperature go up continually in the future,the ground temperature field will take a speedy turn for the worse for a trifling temperature change.The engineering geology characteristics of Qinghai-Tibet railway permafrost area of the plateau included plane distribution characters of frozen ground,distribution characters of river and talik,verticality ,thickness and engineering sub-area characters of frozen ground.All these characteristics will change when air temperature changed. As a example,in fourth chapter,thermal stability and ground temperature change in The Fenhuo Mount test railway roadbed was discussed.Based on a lot of field data,the change trend of roadbed thermal state and the talik process of natural fundament and roadbed was analyzed using numerical method and computer simulation. In the last chapter, some available engineering methods such as lay EPS ,building sun-shading shed,constructing ventilated roadbed have been studied by using numerical method and computer simulation,the effects of these engineering methods has been analyzed also.