Study On The Applicability Of The Evaluation Methods Of Railway Embankment Stability In Permafrost Regions

It has been troubling engineers to construct and maintain the long-term stability of roadways in permafrost regions.The Qinghai-Tibet Railway(QTR)is considered to be a milestone project in permafrost regions,and the feasibility and effectiveness of cooling measures have been proven the construction of the project.The maintenance of the embankment is important to the stability of roadway,while stability evaluation is one of the important methods.In this paper,evaluation models based on fuzzy comprehensive evaluation and catastrophe progression method was established.Stability evaluation against14 cross sections of the QTR was conducted based on the models,and the feasibility of the models were evaluated.The main conclusions can be drawn as follow:The principle and method for the establishment of the index system in stability evaluation of the railway embankment in permafrost regions was determined based on theoretical analysis.Based on literature analysis,the main impact factors on the stability of roadway embankment were found,and they were divided into four types,namely the permafrost condition,the engineering condition,the geological condition and the environmental condition.Then the index system for the stability evaluation of embankment in permafrost regions was established.After analysis of the common method for stability evaluation,fuzzy comprehensive evaluation method and catastrophe progression method was found to be the probable methods for stability evaluation of railway embankment in permafrost regions.The principle and process of the methods were described,and the index weight and classification of evaluation indexes were made for the fuzzy comprehensive evaluation method and catastrophe progression method,respectively,based on the index system and literature analysis.Based on literature analysis,the permafrost and geological condition,application of engineering structures(especially cooling measures),and the embankment stability of the QTR were described.The stability of 14 cross sections,for which most of the evaluation indexes could be found in literature,along the QTR were evaluated after the functioning of 5,30,and 50 years(49 years for the catastrophe progression method)using the methods.The results of the fuzzy comprehensive evaluation method were found in good agree with the monitored result,and was considered to be more applicable in stability evaluation of railway embankment in permafrost regions.