The stability and integral functionality of the flysch costal slopes of the Adriatic in the static and seismic conditions have been analysed, based on the extensive engineering geological, geophysical, geotechnical laboratory and "in situ" investigations. The design model of the endless long slope is made on basis of the geotechnical models which had to be done before. The design model was used for the stability analyses. The method of the slope mass balance analyses of the method which uses seismic coefficient. During the observations, in the area of flysch slopes a lot of cases of slow (longlasting) progressive failure have been found out. This is not the consequence of the change of loading stresses but the change of the shear strength parameters.
Les etudes approfondies et les essais geologiques, geophysiques et geotechniques en laboratoire et en place ont permis l'analyse de la stabilite et de la fonctionnalite integrale des versants cotiers de l'Adriatique dans des conditions statiques et sismiques. L'analyse de la stabilite a necessite un modele geólogique et un modele geotechnique, a partir desquels a ete forme le modele de calcul d'un versant de longueur infinie. La methode de l'equilibre limite du bloc glissant est plus fiable dans les conditions sismique que la methode de coefficient sismique. Dans la region des versants en flysch ont ete observes un grand nombre de cas de ruptures lentes (de longue duree) et progressives, entrainees par la variation des parametres de resistance lors du cisaillement et non pas par la variation des charges exterieures.
Auf Grund ausfuehrlichen ingenieurgeologischen, geophysischen, geotechnischen, laboratorischen und "in situ" Untersuchungen, sind die Stabilitat und Integralfunkcionalitat der Flyschkuestenabhange der Adria in statischen und Erdbebenbedingungen analysiert worden. Um die Stabilitatanalyse durchzufuehren, ist es notwendig ein ingenieurgeologisches, bzw. geotechnisches Modell zu machen, auf dessen Grund ein "Design Modell" des endlosen Abhangs hergestellt ist. Die Methode des Grenzengleichgewichtes des schiebenden Blocks in den Erdbebenbedingungen ist zuverlassiger als die Methode des Erdbebenkoeffizients. Wahrend der Betrachtungen der Flyschabhange sind viele Falle langsamen, langzeitigen, progressiven Bruches festgestellt. Das ist die Folge einer Scherparameteranderung und nicht der Ǎnderung der ausseren Belastung.
Taking part in the work of a bigger investigation team on the project: "The flysch Investigations in the costal Area with the Aim of More Rational, Safer and More Economic Building", financed partly by Self - managing Community of interest for the scientific work in the Socialist Republic of Croatia, two areas have been chosen. The complete investigations have been performed in the last 30 months. It enabled the systematization of the up to now experiences in the process investigation - planning - building - instrumentation and observation at various objects. The following areas are separated: - elastic deposits in the tectonically disturbed area of the town of Rijeka - the disturbed elastic deposits in the zone of the main tectonic contact with the carbonate rocks (the greater area of the town of Dubrovnik). The up to now experiences in investigation, planning, building and instrumentation of objects built in flysch, are not systematized. The main reason is probably the fact that there is the difference in Eocene elastic sediments in composition, tectonic, state and characteristics, which makes investigation, planning, building and instrumentation of the objects in these areas more complicated. With regard to great damages that appear while building and exploitation of the objects in Eocene clastic sediments of the costal zone of the Adriatic Sea as well as to the fact that over 50% of the building area of the coast is placed in flysch and having in mind the future building of the important turistic and industrial objects, the realisation of the investigation programme began in the year 1984. The basic investigation aim has been formulated: systematization of the knowledge concerning flysch and changing the obtained results in recommendations (directives) for more rational processing: investigation - planning - building - instrumentation and the observation of the system object - flysch rock mass. Important problems that appear in building on flysch costal slopes are: - slope stability in conditions determined by their natural surroundings, - the artificial slope stability caused by some human activity in the changed conditions in comparison to the natural ones. To analyse the stabilities it is necessary to make the engineering geological, geotechnical model respectively, with the quantified parameters essential for the calculation in static and seismic conditions. In town planning it is necessary to make geotechnical evaluation of the area which spread over the flysch slopes. For geotechnical evaluation of the area, using the system of the dimensionless coefficients which is usual in geotechnical practice, it is necessary to establish, by preliminary analysis the stability factor in static and seismic conditions and permanent displacements on the potential sliding plane.
