Extended abstract Rockfalls are the most frequent and dangerous type of landslides, generating high economic and social damages in zones built in different types of rock mass. The high danger of rockfall occurrence mainly lies in high speed of the falling rock mass that is very difficult for any fast response in the protection of human lives, settlements and infrastructure. The main part of Adriatic coast of Croatia is built in the limestone rock mass and numerous cities and traffic infrastructure were built in a narrow coastal belt, just below steep slopes of limestone massifs [1]. Numerous cities (e.g. Rijeka, Omiš, Makarska, Dubrovnik) and small settlements, as well as hundreds of kilometres of roads, are exposed to rockfall threats and their consequences expressed in human lives and economic damage. Because of the nature of a rockfall occurrence, where relatively small rockfall volume can cause extremely high damages, there were numerous projects in rockfall protection along the Croatian part of Adriatic coast last years. One of the most comprehensive and by its volume the most important project in Croatia was the City of Omiš rockfall protection project conducted from 2006 to 2018 [2]. After the numerous rockfall occurrences that hit the City during its known history, the modern rockfall protection constructions and new technologies in rockfall analyses and protection designing enabled the development of the efficient rockfall protection systems. In this paper, we will describe the methods of field and remote sensing investigation of rock slopes, identification of rockfall sources, modelling and simulation of rockfall propagation, as well as the selection of protection measures and their positioning at the slopes above the central part of the City of Omiš. The carried out measures and estimation of their efficiency in reduction of rockfall hazard and risk in the central part of the City of Omiš will be described.

No abstract

No abstract

During the last decade, large rockfalls occurred on the steep limestone slopes along the Adriatic Coast of Croatia, causing injury to people and serious damage to buildings and traffic facilities. The rockfalls along the limestone slopes were caused by unfavorable characteristics of the rock mass, weathering in combination with heavy rainfall and artificial influences during highway construction. Rockfall protection projects were conducted to protect human lives and facilities from future rockfalls. The rockfall protection program started with rockfall hazard analyses to identify the potential of rockfalls to occur and the potential consequences. At the locations of hazards where related risks were determined, detailed field investigations were conducted. Based on the indentified characteristics of potentially unstable rock masses, analyses of movement and resulting pathways were conducted. The trajectories, impact energy and the height of bouncing are dependent on slope geometry, slope surface roughness and rockfall block characteristics. Two protection measure approaches were adopted: prevention of rockfalls by removing potentially unstable rock mass or installation of rock mass support systems and suspending running rockfall masses with rockfall protection barriers. In this paper, rockfall hazard determination, rockfall analyses and rockfall protection designs for rockfall protection systems at selected locations on the limestone slopes along the Adriatic coast of Croatia are presented.

The Raspadalica Cliff is an almost vertical 100 m high limestone cliff with a railway line at its foot and is known for numerous rockfall occurrences in the past. This article presents the results of the geotechnical study of the cliff based on a traditional geological and geotechnical field survey and remote sensing analysis. Both the traditional geological and geotechnical field survey and remote sensing surveys and analyses enabled the establishment of the structural model of the Raspadalica Cliff and the determination of the discontinuity sets and discontinuity features, such as orientation, spacing, persistence, roughness, discontinuity wall strength, aperture, degree of weathering of discontinuity wall, seepage conditions, and the presence and hardness of discontinuity filling. Kinematic analyses were performed on five cliff zones with slightly different structural features, indicating a relatively low probability of typical failures in the cliff rock mass that precede the rockfall occurrences. Although rockfall phenomena from the cliff face are relatively frequent, the kinematic analyses did not indicate a high probability of their occurrence. The aim of this manuscript is to make scientists and practitioners aware that investigation of rock mass cliffs and possible rockfall failures must not be based on usual methods without critical review of the obtained results and consequences. The combined use of traditional geological and geotechnical methods and more commonly used advanced remote sensing methods leads to better modelling, while the analysis of more associated failure modes can explain the triggering of rockfall.