Study On The Evaluation Index System Of Service State Of Highway Filling Subgrade

With the extension of highway operation time and the circulation function of the external environment,the service state of the embankment will gradually decay,which will affect the overall function of the road.So it is very important to master the service behavior of embankment by constructing proper evaluation index and combining appropriate evaluation method.On the basis of fully investigating the research results of domestic and foreign scholars on the evaluation of the service performance of Subgrade,the research first analyzes the typical diseases of embankment,then studies the evaluation Index system of the filling Subgrade service performance,and constructs the evaluation model systematically.The main research results include the following aspects:(1)Through the analysis of the relationship between Subgrade disease and the service behavior of Subgrade,it is concluded that the subgrade disease is not enough to reflect the service behavior of Subgrade.It is difficult to visually characterize the“Subgrade strength status”—the key index of the roadbed evaluation.The evaluation of the service status of embankment should be considered from 3 aspects of roadbed stability,subgrade deformation and subgrade strength.(2)Combined with the disease types and degrees of subgrade,the paper puts forward a multi-level index system which is determined by the strength index of subgrade structure,uneven settlement index of subgrade and stability index of Subgrade as control index.In this research,the strength coefficient of subgrade structure is put forward to reflect the strength of subgrade structure.and the function relation between the strength index of subgrade structure and the strength coefficient of subgrade structure is builded.Given the driving comfort and the damage of pavement structure,the differential settlement slope control criterion for uneven settlement of Subgrade is proposed.The paper puts forward that the ratio of over-slope is used to characterize the uneven settlement of Subgrade,and the corresponding relationship between uneven settlement index and over-slope rate is established.The stability of Subgrade is comprehensively reflected in 6 aspects,such as the geometry condition of subgrade,the quality of soil filling,the rainfall,the defect status of retaining structure,the defect condition of the drainage system and the condition of embankment slope,and divides the quantity of each sub-index and its deduction range.(3)By using the expert scoring method,the weights vectors of all indexes are determined preliminarily.The Pauta Criterion is applied to the selection of expert individual weight vectors,and the Pauta Criterion is improved to make the weights of all levels more reasonable.On the premise of determining the weights of various indexes,a comprehensive evaluation model for the service behavior of embankment is proposed.The fuzzy comprehensive evaluation method is applied to the evaluation,and a fuzzy evaluation model for the service behavior of Embankment is preliminarily established.(4)Using the established evaluation model to evaluate the service status of the "Chang Wan Expressway" filling section,and obtain the condition of the service state of the embankment in the investigation section.The application results show that the evaluation model of the service behavior of embankment has good applicability.The results of fuzzy Evaluation and Index system evaluation are consistent.The research results provide basis for the evaluation of the service behavior of the embankment,and provide some reference for the formulation of the relevant standard.