Abstract: Artificially frozen wall is a temporary support structure in tunnel freezing engineering; and frozen wall will gradually thaw after construction of the tunnel lining. In the process of frozen wall thawing, thawing settlement of ground can produce serious influence on the surrounding environment. So a reasonable method must be established for predicting surface thawing settlement. On this basis, suitable thawing settlement prevention measures can be determined in the actual construction. For this reason, considering the thawing process of frozen wall, using stochastic medium theory, a duration prediction model of surface thawing settlement in the period of tunnel construction with horizontal freezing method is presented. Temperature field under natural thawing conditions can be approximately analyzed by flat-panel thawing theory; based on flat-panel thawing theory and thawing settlement content calculation formula in one-dimensional case, value methods of thaw front radius and thaw compression region inner radius are determined in the duration prediction model. The prediction method is applied to circular tunnel full section horizontal freezing engineering, surface thawing settlement variations with thawing time are presented. The results show that surface thawing settlement grows faster in the early stages of thawing, and grows slower in the later stages of thawing. Surface thawing settlement variations with thawing time is presented, which is consistent with thawing settlement characteristics of natural permafrost researched through test method by ЦЫТОВНИЧ.

Key words: tunnel freezing, surface thawing settlement, thawing process, prediction model, stochastic medium theory