ABSTRACT
Artificial Ground Freezing (AGF) was used for the temporary support for four out of seven sprayed concrete lining (SCL) cross passages on the Silvertown Tunnel project. Three of these cross passages were constructed under the River Thames, while the fourth was located onshore on the Greenwich peninsula. The cross passages were situated within the Lambeth Group, distinguished by interbedded layers of over-consolidated sand and clay with cover as low as 13m. An overview covering the site’s ground conditions, laboratory testing results of frozen soil samples, and the selected geotechnical design parameters is provided, followed by a summary of the thermal design, freeze pipe layout details, and considerations made for the structural design of the cross passages. Construction aspects, including records of the surface settlements, ground temperature monitoring, target temperature criteria, freeze durations, and thermal imaging, are also presented. The paper concludes an evaluation of the method, offering recommendations based on the project experience.
