Integrated Prediction Model of Ground Surface Deformation During Tunnel Construction using Local Horizontal Freezing Technology

Different from the traditional tunnel construction, the tunnel construction using artificial horizontal freezing technique needs to go through three stages: soil freezing, tunnel excavation and frozen soil thawing. Each construction stage will produce different degrees of ground deformation, which has a great impact on the surrounding environment of the tunnel. In this paper, the whole process theoretical prediction model of ground surface deformation is established based on the stochastic medium theory by introducing the parameters of ground loss rate and average degree of consolidation. Besides, the whole process numerical prediction model is established by programming the transient temperature volumetric strain of frozen-thawed soil based on ABAQUS. The theoretical and numerical prediction models are verified by the measured data of Fu-ba tunnel construction using local horizontal freezing technique. The results show that the ground surface deformation law obtained by the theoretical and numerical prediction models is basically consistent with the field measurement, and the prediction accuracy of the maximum vertical displacement of the ground surface is high. Besides, the numerical prediction model can accurately reveal the evolution law of the formation temperature field and displacement field, and the stress field of tunnel lining can be used as a reference for the design of tunnel structure. It is suggested that the combination of theoretical and numerical prediction models should be used to predict the whole process of ground surface deformation in the tunnel construction using artificial horizontal freezing technique, so as to take protective measures in advance.