Ground Freezing - Principles, Applications and Practices

This article describes the application of ground freezing, considered to be an effective stabilizing technology, in tunneling and underground construction projects. The article gives a detailed discussion of the principles involved in ground freezing, where heat is withdrawn from the soil in order to impart strength to the soil particles and create a watertight and impermeable frozen soil mass. The article discusses frozen soil behavior, focusing on the impact that groundwater flow can have on freezing. This is followed by a description of the design of ground freezing systems, and monitoring and quality control in the ground freezing process. The article concludes with a discussion on contracting practices for ground freezing and how they vary between the U.S. and Europe. The Brightwater Conveyance Project in Seattle, Washington, is presented as an example of the vertical ground freezing practices in the U.S., while the Westerscheldetunnel project in the Netherlands and the Dusseldorf mass transit subway system expansion project in Germany are presented as examples of horizontal freezing used in Europe.