Grouting is performed since nearly 2 centuries all over the world, but a theory of grouting could not be developed till now. The reasons are not only the heterogeneity of the underground, but mainly the fact that the different flow properties of the water and the grout are not considered in the evaluation of the permeability tests (performed with water), and the lack of knowledge of the relevant characteristic properties of the grout fluid, and of the pressure acting in the joints.
Des injections sont executees depuis presque 2 siècles de par Ie monde, mais une theorie des in-jections n'a pas pu être developpee jusqu'à present. Les raisons sont non seulement la heterogeneite du soussol, mais principalement le fait que les differentes proprietes d'ecoulement de l'eau et du coulis ne sont pas considerees dans l'evaluation des essais de permeabilite (realises avec de l'eau), et le manque de connaissance des proprietes caracteristiques pertinentes du fluide d'injection, et de la pression agissant dans les diaclases.
Injektionen werden seit fast 2 Jahrhunderten in der ganzen Welt durchgefuehrt, doch eine Injektionstheorie konnte bisher nicht entwickelt werden. Die Gruende sind nicht nur die Heterogenitat des Untergrundes, sondern hauptsachlich die Tatsache, daβ die verschiedenen Flieβeigenschaften des Wassers und der Zementmilch in der Auswertung der (mit Wasser durchgefuehrten) Durchlassigkeitsversuche nicht beruecksichtigt werden, und der Mangel an Kenntnis der relevanten charakteristischen Eigenschaften der Injektions fluessigkeit, und des in den Klliften wirkenden Druckes.
Subsurface grouting was executed successfully for the first time in France at the beginning of the 19th century (Glossop 1961) for the purpose of improving foundation properties. Since then this method has spread throughout the world. Many methods and many grout materials have been developed to meet most different conditions and requirements. However, it is not possible till now to forecast and to describe the grouting process in situ by means of calculations. At a time when many people believe on the omnipotence of the computer the theory of grouting is in its academic infancy. One of the main arguments against the attempts to develop a theory of grouting is the fact that the heterogenity of the underground, especially of the rock mass, does not allow such a theory. However, if we make a few water pressure tests, we believe to have the fundamental parameters for the calculation of sea page over large areas. We need these tests for the decision weather grouting is necessary or not. We make very few grouting tests in situ and believe to have the answer for these questions and think that they are representative for the entire area to be grouted. Therefore we are believing in a way on the uniformity, which does not exclude that in some cases a special treatment of limited areas may be necessary. These questions should be answered not only to leave the method of trial and error used till now, when the success of the grouting work depends on the experience of the man at the pump. These questions should be answered too to enable a more reliable cost estimation before starting the grouting work. Only if we know these two groups of parameters we get a feeling for the interaction between rock and grouting and we get nearer to the cost of a successful grouting work.
To perform an economical and successful grouting work the knowledge of three groups of characteristics is indispensible (Fig. 1): The geological description of the rock is the basis of each treatment of the underground.
