Simulation Of Temperature Field Distribution Of Permafrost Along The Qinghai-tibet Railway

In recent years,global warming leads to rising ground temperature and serious degradation of permafrost.The degradation of frozen soil in the Qinghai-Tibet Plateau is particularly severe.The Qinghai-Tibet Railway has played a huge role in the economic and social development of China's western regions.The permafrost area along the Qinghai-Tibet Railway has complex geological conditions and fragile ecological environment,and the permafrost is extremely sensitive to the change of ground temperature,which directly affects the engineering safety and sustainable development in cold regions.Therefore,it is particularly important to simulate the permafrost geothermal field along the Qinghai-Tibet Railway by using a certain model method to obtain the distribution characteristics of the permafrost geothermal field and the variation rule of the active layer thickness in the study area.At present,the study on the simulation of permafrost temperature distribution on the Qinghai-Tibet Plateau considers the influence of various factors,but does not consider the spatial non-stationary characteristics between the permafrost temperature and influencing factors and the problems that the permafrost thermal parameters are not necessarily constant,and the multicollinearity problem between the permafrost temperature and the influencing factors still exists.Therefore,in view of the above mentioned problems,this paper toke the Kunlun Mountain-Chigu section along the Qinghai-Tibet Railway as an example to carry out the following work:(1)Collected and sorted out the measured ground temperature data of the railway engineering boreholes in the study area.The spatial distribution characteristics of the measured ground temperature data and the variation characteristics of ground temperature with depth were also analyzed.(2)Eleven influence factors of permafrost temperature were selected from three aspects of geographical elements,meteorological conditions and local factors.Pearson analysis,multicollinearity detection and spatial non-stationarity analysis were carried out between 11 permafrost temperature influencing factors and measured ground temperature data.Principal component analysis(PCA)was used to eliminate the multicollinearity among the influencing factors of permafrost temperature,and seven independent explanatory variables were determined for the simulation of permafrost temperature field.(3)The model performance of the external drift Kriging model(KED)geographically weighted regression model(GWR)and geographically weighted regression Kriging model(GWRK)were verified.The GWRK model was selected to simulate the spatial distribution of permafrost temperature field from Kunlun Mountains to Chiqu Valley along the Qinghai-Tibet Railway.The distribution characteristics of permafrost temperature field from July to September 2001 in this region were analyzed,and obtained the active layer thickness of permafrost in the study area.Finally,the accuracy and reliability of the simulation results were analyzed.The experimental results shown that there is multicollinearity among the 11 influencing factors of permafrost temperature selected in this paper,and there is spatial non-stationarity between the permafrost temperature and influencing factors of permafrost.KED,GWR and GWRK can be used to simulate the temperature field distribution of permafrost along the Qinghai-Tibet Railway.Among them,the model performance of the GWRK model is better than the KED model and the GWR model,and the simulation results are highly reliable.The research results of this paper could provide a data basis for the sustainable development and ecological environmental protection of permafrost areas along the Qinghai-Tibet Railway.And the research of this paper would have certain reference value for the simulation of geothermal field distribution of Sichuan-Tibet railway.