Prediction of freezing-induced movements for an underground construction project in Japan

This paper presents the results of a thermomechanical simulation of freezing around an existing tunnel in Kobe (Japan) to predict the deformations associated with ice lens formation and those resulting from thaw after construction is completed. The frost heave characteristics used in the numerical model were obtained from laboratory freezing tests conducted on undisturbed samples provided by the Osaka Soil Test Laboratory. With the planned construction schedule, the predictions suggest a maximum frost heave at the ground surface of about 4.8 cm while the expected thaw settlement in the tunnel's centerline was about 13 cm. Observed frost penetration and surface frost heave movements agree well with the predictions. Grout injected during thaw was successful in preventing excessive thaw settlement.Key words: frost, soils, heave, model, monitoring, field.