Temporary Tunnel Support by Artificial Ground Freezing

The major considerations involved with evaluating artificial ground freezing for temporary tunnel support are described. To illustrate the general design process, three study cases where ground freezing was evaluated for tunneling beneath mainline railroad tracks are presented. A laboratory testing program, consisting of both static creep tests and repeated load triaxial tests, was conducted to define the strength and deformation characteristics of the case study soils frozen to -7°C and -10°C. It was determined that the stress-strain characteristics of the frozen soil could be approximated by a hyperbolic function. The finite element method was used to calculate the stress distribution in the frozen tunnel liners.