Abstract: For the study of freezing expansion speed of Cretaceous soft rock strata, in order to achieve the purpose of shaft excavation in advance. Through the study on the risk of four deep water hole and brine cooling gradient of soft rock strata in the Cretaceous, study concluded that: Asabu Minkong should be set carefully, and the prediction of shallow frozen wall to circle should use other methods to replace; the cretaceous soft rock freezing expansion rate of V presents the linear relationship with the way salt water cooling gradient T, linear regression equation V = -17.653T + 12.444;. And the research analysis puts experience value 25mm/d of the freezing expansion speed in soft rock strata of Cretaceous before ringing.

Key words: Cretaceous soft rock, frost wall, regression analysis, expansion speed, temperature gradient