This paper deals with the thermal design, sensitivity analyses and monitoring of the ground freezing in the Amsterdam North/South Line metro project. On two occasions in 2008 water and soil washed through a joint of the diaphragm wall at the "Vijzelgracht" metro station right in the historic city centre. This led to severe damage of houses adjacent to the station. The quality of all the joints in both Vijzelgracht and Rokin station was questioned, leading even to a questioning of the feasibility of the total project. As a measure to seal these joints, ground freezing is applied at every joint for the remaining excavation levels at the two station boxes. At each joint two freezing pipes are placed at the inside of the station. In total over 400 freezing pipes are used in the project. The paper describes the thermal design of the freezing pipe layout and the sensitivity analyses to minimise the risks during construction. In the design and also during monitoring, a combination of thermal and groundwater flow FEM calculations is used to control the freezing process. The excavation of both Vijzelgracht and Rokin station is now successfully finished. The ground freezing measure has proved to be successful in ensuring a watertight joint in complex circumstances.
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