ABSTRACT
In many cities around the world much of the favourable ground conditions have already been utilised for various purposes. As a consequence, new underground excavation is often forced to be constructed in unfavourable ground. In tunnelling, this can imply excavating with inferior or even without sufficient rock cover. Moreover, demands and regulations, from the society and project owners, concerning environmental impact are becoming increasingly strict. Ground freezing is an effective method to enable excavation through unfavourable or unexpected ground conditions, and it is an environmental friendly method that does not produce any hazardous waste. In Stockholm, ground freezing has been used in two tunnel projects, where parts of the tunnel pass through soft ground or soil. One of the projects has been completed by using liquid nitrogen, and the other by using brine.
