In the last decade, with the demand for utilization of natural resources for power developments, the use of water jets for rock cutting, tunneling and mining has found extensive application. In comparison to excavation by means of blasting, water jets have the advantage that the excess excavation beyond the planned cross section is marginal and that the load sharing capacity of the rock mass is retained. By inducing cavitation in the water jets, which increase the cutting capability, hard rock tunneling is possible by fitting an array of water-jet nozzles to a conventional tunnel boring machine. In this paper the several features and techniques of liquid jet cutting with special reference to tunnels and caverns are discussed. The characteristic features of the erosion caused on rocks and minerals with the variation of several parameters are presented. The state of art of the cutting techniques in the last decade is presented.
Im letzten Jahrzehnt hat mit der Notwendigung natuerliche Quellen zur Energiegewinnung heranzuziehen, der Gebrauch des "water jets" in Bezug auf die Schneidbarkeit von Fels, als auch im Tunnel- und Bergbau erheblich an Bedeutung gewonnen. Im Vergleich mit den herkömmlichen Ausbruchsmethoden haben "water jets" den Vorteil, daG der Mehrausbruch gegenueber dem planmaβigen Querschnitt auβerordentlich gering ist und die Festigkeit des Gebirges erhalten bleibt. Indem eine Kavitation im "water jet" erzeugt wird, steigt die Schneidfahigkeit und es ist auch möglich, harte Gebirge durch die Kombination einer konventionellen Tunnelbohrmaschine mit einer Reihe von "water jet"-Duesen zu lösen. In diesem Beitrag werden verschiedene Arten und Techniken von fluessigkeitsgestuetzten Schneideverfahren in Bezug auf Tunnel- und Kavernenbauten diskutiert. Charakteristische Besonderheitem beim Lösen von Gesteinen und Mineralien mit einer Variation der verschiedenen Kennwerte werden vorgestellt. Auβerdem wird die Entwicklung der Schneidetechniken im letzten Jahrzehnt dargestellt.
Pendant cette dernière decade, à cause de la demande d''utilisation des ressources naturelles pour des developpements de l''energie, l''usage des "water jets" dans Ie decoupage des roches, Ie forage des tunnels et l''exploitation des mines a trouve une application intensive. Comparativement à l''excavation au moyen d''explosif, les "water jets" presentent l''avantage de reduire les debordements hors du profil prevu et de preserver la portance du terrain. En produisant une cavitation dans les jets d''eau, ce qui accroît leur capacite de decoupage, l''equipement d''une foreuse de tunnel conventionnelle d''une gerbe de pulverisateurs de jets rend possible Ie forage des tunnels dans les roches dures. Les differentes caracteristiques et techniques relatives au decoupage au jet de liquide sont discutees dans cet expose avec une reference speciale aux tunnels et aux cavernes. Cet expose presente egalement les traits caracteristiques de l''erosion des roches et des mineraux qui en resulte ainsi que la variation de plusieurs paramètres. De plus, la situation de l''art des techniques de decoupage y est rapportee.
In the last two decades man''s search for the optimum utilization of natural resources for power development has increased fivefold. The increase in world population and expectation for the improvement in the quality of life, has led to an increased demand for energy. Among the sources of energy, the utilization of Hydro-potential caters to a larger percentage. Further, the majority of mineral wealth and fossil energy of the world is located at depth and this requires increased volumes of rocks to be penetrated each year in order to satisfy the world''s demand. All the potential energy resources must therefore be exploited if the energy crunch is to be reduced to an uncomfortable squeeze. Almost all these resources are in hilly terrains and the case of Development of Hydropower tunneling is extremely important.
From time immemorial, rock has been broken by either the impact of a relatively sharp-edged tool against the rock, or by the dragging of a relatively sharp-edged tool across the rock surface. In recent years relative sophistication has been achieved in drilling rigs and its components.
Since inception rock drilling has undergone relatively very little revolutionary changes. The method of breaking the rock essentially remains the same i.e. the drilling of holes within the rock surface, the holes filled with explosives and ignited, thus breaking relatively large volumes of rock. However, evolutionary changes have been observed in the fact that the drilling equipment has become larger and more sophisticated. However, a better control of the environmental features such as noise, dust and hazards to the mining operator have not been achieved substantially. Novel systems developed usually requires a lead time of 10 to 20 years between conception and widespread adaptation. In the geotechnical field, water jet cutting technology, is in the state of major evaluation (1–9).
