Based on many years of research focusing on a number of significant structures (bridges, tunnels, dams, high rock slopes, etc.) designed and realized in the Adriatic coastal area, we have collected a large quantity of engineering-geological and geotechnical information. To devise engineering geological (IGM) and geotechnical models (GM), it is indispensable to conduct engineering rock-mass classification using one of the widely recognized methods. Starting from the existing RMR and Q classifications, we have developed a new "n" classification which enables a more complete limestone classification and categorization, using a relatively simple procedure.
En se basant sur plusierus annees de recherches portant sur un grand nombre de grands ouvrages (ponts, tunnels, barrages, talus rocheux eleves, etc.) etudies et realises dans la zone côtiere de I'Adriatique, nous avons ramasse une grande quantite des donnees geologiques et geotechniques. La classification de la masse rocheuse selon une des meethodes reconnues dans Ie monde est indispensable pour I'etablissement des modeles de geologie de l'ingenieur (IGM) et des modeles geotechniques (GM). En partant des classifications existantes "RMR" et "Q", nous avons developpe une nouvelle classification "n" qui perment une categorisation des calcaires plus complete, a l'aide d'une procedure relativement simple.
Auf Grund unserer langjahrigen Forschungen an einer Reihe großer Objekte (Bruecken, Tunnels, Staudamme, Felswande usw.) die in der adriatischen Kuestenregion errichtet wurden, haben wir eine große Menge von ingenieurgeologischen und geotechnischen Angaben gesammelt. Um ingenieurgeologische (IGM) und geotechnische (GM) zu entwerfen, ist es notwendig, eine Ingenieur-Klassifikation von Gesteinsmassen nach einer der anerkannten Methoden durchzufuehren. Ausgehend von bestehenden Einordnungsverfahren "RMR" und "Q" haben wir eine neue "n" Klassifikation entwickelt, die ein vollstandigeres Einordnen und Kategorisieren von Kalksteinen ermöglicht und verhalnismassig einfach ist.
Croatia's development in the period after 1990 is marked by an increasing global trend of investing in transportation infrastructure. According to estimates presented in various design solutions, approximately 30 to 50 km of road tunnels are to be built on the following highway routes: Zagreb-Maribor, Zagreb-Split (Zadar), Zagreb-Varaždin, Rijeka-Karlovac, Rijeka- Trieste, Rijeka-Dubrovnik. In addition, about 50 km of tunnels are to be built along the approx. 150 km long valley railway line Zagreb-Karlovac-Rijeka. Furthermore, a tunnel approx. 12–15 km in length is to be built through Ćićarije on the railway line stretching from Rijeka to Pula [Jašarević, 1993]. It should also be noted that an intensive urban development of medium-sized and large cities-aimed at revitalizing the existing city centers-has brought about significant traffic and environmental problems that may be resolved in a rational manner by building appropriate underground structures. This particularly applies to large cities situated along the Adriatic coast (Rijeka, Split, Dubrovnik, Šibenik). From the engineering-geological and geotechnical standpoint, the rational and cost-effective design and construction of underground structures must be based on the knowledge of essential rock-mass properties: occurrence of fissures (discontinuous environment), heterogeneity, anisotropy, and natural (primary) stress. In fact, the fissuring exerts the greatest influence on geotechnical properties, i.e. on the design and construction of underground structures in rock massif, which is why this element has been given an appropriate significance in the rock-mass classification (5 out of 11 classification parameters-Table 2). As to traffic corridors, it is important to note that most significant underground structures have been designed and are to be built in the coastal area of Croatia. Limestone formations from the Jurassic and Cretaceous period are present on over 50% of the total coastal area of the Republic of Croatia. Several classifications and categorizations of limestone formations, based on international experience and many years of research conducted in our country, are presented. In addition, the procedure for determining (selecting) geotechnical parameters required in the corresponding calculations is given.
