The Analysis Of Gravel Settlement And Temperature Field Of Highway Composite Foundation In Patchy Permafrost Regions

Road construction in permafrost area will inevitably change the natural hydrothermal conditions of the soil,the redistribution of temperature field will cause the embankment and the limit change of surrounding permafrost, leading to thaw disaster,and then damage pavement performance. Under the double impact of climate and engineering activities, temperature of foundations in permafrost increased, large amounts of water loss from the permafrost, The overall strength and stability of the foundation the significant declined, under the repeatedly role of load,overflowed water and soil material formed slurry, which greatly affect the way the use of performance play.To understand the response process of the temperature of permafrost foundation and long-term deformation characteristics of the roadbed under climate change is the basis to solve the problem of long-term stability of embankment.This research uses the design principal of accelerating melting rate of permafrost,based on QianNen road project.This research applies composite foundation gravel pile treatment to deal with the permafrost near Kunlun gas crossing from Yichun to Beian-Cuiluan area, in order to avoid the sedimentation after construction and reduce the occurrence of permafrost disaster during working period of the road.This research will carry on the following works:1.Set temperature and sedimentation tube on QianNen road,observe temperature and sedimentation about freeze-thaw cycle foundation,and analyze temperature and sedimentation data.2.It is found that the soil shows an overall endothermal state throughout the year by observing and analysing the fracture area, and it indicates that permafrost is in degradation gradually.The existence of the gravel pile increases the thermal conductivity of the composite foudation,thus speeding up the melting of permafrost.3.Apply ABAQUS to establish the finite element model of the temperature field and the settlement deformation based on Laboratory test data.Then observe and anlyze the temperature distribution in one cycle of the test road section,predict the depth of permafrost melting and the sedimentation amount after the design working life of the road.