Subgrade Stability Evaluation in Permafrost Regions Based on Unascertained Measurement Model

With regard to the complex and changeable engineering properties of subgrade in the permafrost regions, a stability-evaluating and order-arranging model of subgrade in permafrost regions is established based on the unascertained measurement theory. Subgrades of Qinghai-Tibet Railway in permafrost regions is taken as examples in view of the unique geological environment conditions. Twelve factors, which influence the subgrade stability, are selected as the evaluation indexes and analyzed qualitatively and quantitatively. The grading standard and stability evaluation index system are constructed. Entropy theory is used to calculate the index weights of evaluation factors, and the stability grade of five typical sections in permafrost regions is judged by credible degree recognition criterion. Meanwhile, the stability of permafrost subgrade is sorted according to evaluation sorting values. It is shown that the results offered by unascertained measurement model assessment are consistent with those by the fuzzy evaluation method. Furthermore, the proposed method can take into account the unascertained information in stability evaluation, which provides an effective method for the subgrade stability evaluation in permafrost regions.