ZAI contributes two articles in
the journal Geotechnik

September 2020

In the third issue of Geotechnik (43rd volume, issue 3, September 2020) ZAI is contributing two articles.

In the article entitled "Forecast model for soil movements caused by dewatering – Development and previous application in the Rhenish lignite mining area", Prof. Aulbach, Prof. Ziegler and Mr. Ruoff of RWE Power AG report on the development of a model based on soil mechanics principles for modeling current and forecasting further soil movements caused by dewatering. The model has already been applied in the Rhenish lignite mining area by RWE Power AG in the framework of evidence required by mining law and in the framework of environmentally relevant investigations by the Landesamt für Umwelt, Natur und Verbraucherschutz NRW. Observed and measured soil movements were qualitatively and quantitatively very well mapped and future soil movements could be forecasted based on this. The model can easily be adapted to new boundary conditions and can in principle be transferred to other lignite mining areas or adapted for other applications.

In their report entitled "Block injection for tunnel sealing – State of the art or call for negligence" Prof Ziegler and Mr. Schröder deal with the sealing of tunnels excavated by mining operations with a waterproofing geomembrane (GM). Leakages occur repeatedly after the mountain water level has risen again, as the GM is pressed against potential defects on the outside of the inner concrete shell. Therefore, in Austria and Switzerland, cement is injected between the GM and the concrete inner liner (block backing) according to the local regulations. In Germany, on the other hand, according to the applicable rules and regulations, only one grouting in the roof ridge and the installation of an additional testing and injection system is carried out as planned. Proponents of this system argue that a block injection does not allow for a later direct control of possible water ingress and therefore less attention is paid to the manufacturing quality of the inner shell. Thus, the report discusses the question of whether subsequent water ingress is solely due to poor workmanship or if there are also system immanent causes and consequently if the procedure currently applied in Germany still corresponds to the state of the art.

Both articles are currently available online at the following link:

https://www.ernst-und-sohn.de/geotechnik