Artificial Ground Freezing of Fully Saturated Soil: Viscoelastic Behavior

Abstract

The transport and mechanical properties of saturated soil drastically change when temperatures drop below the freezing temperature of water. During artificial ground freezing, this change of properties is exploited in order to minimize deformations during construction work and for groundwater control. Whereas for the latter only the size of the frozen-soil body is relevant, which is obtained by solving the thermal problem, the design of the ground-freezing work for support purposes requires information about the mechanical behavior of frozen soil. In addition to the quantification of the improvement of mechanical properties during freezing, information about the dilation associated with the 9% volume increase of water during freezing is required in order to assess the risk of damage to surface infrastructure caused by frost heave. In this paper, a micromechanics-based model for the prediction of both the aforementioned phase-change dilation and the elastic and viscous properties of freezing saturated soil is presented. Hereby, the macroscopic material behavior is related to the behavior of the different constituents such as soil particles, water, and ice. Combined with the solution of the thermal problem, the proposed model provides the basis for predictions of the performance of support structures composed of frozen soil.