During the ground freezing process, the soil is temporarily frozen by extracting latent heat, thus increasing the stability and sealing the ice formation of the fissure and pore water. Liquid nitrogen or natural brine are used as freezing agents. This method is used for temporary stabilization and sealing during the construction of cross passages or to close gaps in the sheeting where pipes cross. The advantage of this method is that, once the frozen mass has thawed, no residues remain in the soil and that this method can also be used to close groundwater windows. With the aid of small scale drilling technology, freeze pipes, through which the freezing agent runs, are accurately positioned in the ground. To check whether the freezing was successful, the soil temperature is monitored by means of temperature pipes, which are also drilled.