Martina Vivoda

A complex landslide in the Rječina Valley: results of monitoring 1998-2010

Results of landslide monitoring undertaken between 1998–2010 on the north-eastern slope of the central part of Rjecina Valley in front of Grohovo village (north-eastern coastal part of Adriatic Sea, Croatia) are presented. This is the largest regional active landslide. The slopes around the Rjecina riverbed are formed in siliciclastic sedimentary rocks with flysch characteristics. The bedrock is mostly covered with unstable slope formations. A limestone rock mass is visible on the cliffs around the top of the river valley. The landslide is complex and retrogressive, with 13 sliding bodies. It occurred in December 1996 by displacement of an initial landslide body where movement had been registered in the 19th century. The limestone mega-blocks and separated rocky towers on the top of the slope have also moved, which is an atypical phenomenon of the flysch slopes in the area of Rijeka. After initial sliding ceased, and major movements subsided, monitoring of benchmark movements from 1998 until 2010 determined further maximum displacements on the upper part of the slope, and minimum movement in the lower part. The area of the Rjecina Valley from the Valici Dam to the Pasac Bridge was selected as a pilot area in the framework of the Croatian-Japanese bilateral joint research project. Monitoring results provided the basis of establishing an early warning system for possible landslide occurrence and estimating the degree of landslide risk.

Study of Landslides in Flysch Deposits of North Istria, Croatia: Landslide Data Collection and Recent Landslide Occurrences

The northeastern part of the Istrian Peninsula in Croatia is built of Palaeogene flysch deposits, in which instability is common and where a large number of landslides, with significant consequences, have been recorded. Study of landslides in flysch deposits of North Istria will be conducted as one of the main activities of ongoing IPL-184 Project. It includes analyses and recognition of sliding mechanisms to use in landslide modelling and to determine landslide susceptibility and hazard in flysch rock mass deposits. Several landslide types, mechanisms and conditions occur in the study area. The majority of studied landslides occurred during the spring and winter. Generally, the landslides are of rotational and translational sliding type, and rarely rock falls and debris flows. Local roads and rarely other structures and facilities suffered major damage as a consequence of the landslides. Landslide inventories, as well as landslide susceptibility maps, have never been carried out in the study area. Today’s knowledge about landslides in this area is based on investigations of individual landslides and partial scientific research. After the project started, some of the activities from all stages of the project have been initiated. The proposed first stage of the project includes supplementation of the existing database, and field investigations of recent and existing landslides in the study area, as well as soil sampling for laboratory testing. Moreover, the methods used for landslide susceptibility and landslide hazard assessment are presented. This paper presents the current state of investigations and research in the initial stage of the IPL-184 Project.

A Landslide Monitoring and Early Warning System Using Integration of GPS, TPS and Conventional Geotechnical Monitoring Methods

An advanced comprehensive monitoring system was designed and used on the Grohovo Landslide in Croatia. Equipment selection was based on scientific requirements and consideration of possible ranges of monitored values and sensors precision. Establishment of an early warning system and defining of alarm thresholds is based on existing knowledge of the landslide behavior as well as collected comprehensive monitoring data. The focus of the early warning system establishment at Grohovo Landslide was on an effective combination of sensors (equipment fusion) with respect to detecting device malfunctions and reducing false alarms in the future. The weakest component in the Grohovo Landslide monitoring system is power supply based on solar devices, field data collecting and the data transmitting from the field PC to the control room at the University of Rijeka. This paper presents the main ideas and advances of the monitoring equipment fusion as well as weaknesses of the applied monitoring system at the Grohovo Landslide.

Landslide Susceptibility Assessment on Slopes in Flysch Deposits: A Deterministic Approach

This paper presents detailed landslide susceptibility analyses performed in an existing three dimensional model developed for simulation of progressive failure phenomena. Investigated area is built in flysch deposits, placed in the north-eastern part of the Istrian Peninsula, Croatia. This region is well known as an area of frequent, small and shallow instability phenomena, mostly triggered by rainfall. Performed analysis provided landslide susceptible areas which correspond to the real conditions in the slope. The results have shown that except for the detailed 3D analysis of slope stability at one specific location, LS-RAPID software can also be used for the deterministic landslide susceptibility analyses in wider area.

Marine Erosion and Slope Movements: SE Coast of the Krk Island

This paper presents the interaction of the marine erosion and slope movements on the south eastern coastal area of the Krk Island, Croatia. Larger parts of the coastal bedrock are carbonate rocks, and smaller parts are marls and flysch. The bedrock is occasionally covered with Quaternary sediments, which are characterized in terms of engineering soil properties. Complex geological fabric of the coastal area around Stara Baska settlement, in the south western part of the Krk Island, caused different movements on the coast. Due to the different grade of fissuring and karstification, as well as different weathering grade, carbonate and siliciclastic rock mass have wide range of resistance to the sea effects including wave attack. Exposure to the wave attack generated due to winds from the south directions contributes to the decreased resistivity. Additionally, occasional torrent flows and intensive erosion cause sporadic higher slope instability. The, effect of the previously registered extremely high tides, as well as the possible hazard increase due to the estimated sea level rise, is also analysed in the paper.

Landslide Knowledge Exchange Through the Regional Cooperation in the Adriatic-Balkan Region

Regional cooperation among ICL members in the Adriatic-Balkan region has been initiated at the beginning of 2012 by establishing the ICL Adriatic-Balkan Network on Landslides which encompasses seven institutions from four regional countries, Albania, Croatia, Serbia and Slovenia. The objectives of regional cooperation are to conduct regional cooperative research and capacity building in landslide study and related risk prevention and mitigation for the benefit of society and the environment. This paper presents an overview of the main ICL ABN activities in the period from the beginning of 2012 to the end of 2013. One of the main activities was launching regional thematic conferences on landslides by organizing the 1st Regional Symposium on Landslides in the Adriatic-Balkan Region (1st RegSyLAB) in Zagreb, Croatia in March 2013. The social and technical program of the symposium enabled the participants from nine regional countries to share their experiences about local landslide research at the regional level and enhance the establishment of relations between scientist in the region which are important for future cooperative research and capacity building. This paper describes in more detail the technical sessions and side events of the 1st RegSyLAB, so as report symposium’s outcomes as they relate to the promotion of landslide science.

TXT-tool 3.081-1.6: Manual for the Undrained Dynamic-Loading Ring-Shear Apparatus

The development of the ring shear device was upgraded since 2010, particularly for the loading system. Previous version of the ring shear apparatus of DPRI series has a long loading frame consists of pillars and beam for the normal stress system. Recently, loading piston through the single central axis was applied for the normal stress in the newest version of ring shear apparatus. There are two version of this new apparatus, called the ICL-1 and the ICL-2. The ICL-1 version was developed since 2010 as a part of SATREPS project for ‘Risk identification and land-use planning for disaster mitigation of landslides and floods in Croatia.’ Meanwhile, the development of the ICL-2 was carried out since 2012 as a part of SATREPS project between Japan and Vietnam for ‘Development of landslide risk assessment technology along transportation arteries in Vietnam’. As for practical purpose, both version of the undrained dynamic-loading ring-shear apparatus were designed in a small dimensions (compare with DPRI series) but with high performances. Thus, shallow landslide as well as deep landslide can be simulated geotechnically using this apparatus. In this paper, the structure, control and loading system of the apparatus are described in detail. The testing procedures and data analysis of ring shear tests are also explained.

Remedial Works on the Smrecje Landslide, Croatia

The Smrecje Landslide was occurred on the county road near the Gerovo village in Gorski Kotar region, Croatia, before more than 10 years. The landslide location is forming in clastic formations of shale, sandstone and marl rock masses from Triassic age. The landslide was overtaken 100 m long part of the road construction. The instability was evidenced in long term creep process with deformation increments associated with the seasonal water content variations in the clayey superficial deposit. Deformations on the pavement construction were reaching unacceptable values during 2008 that caused necessity of complete landslide remediation. Field investigations were executed and the remediation measures were designed. Field investigations were included investigation drilling, soil and rock mass samples taken, geophysical measurements using seismic refraction and geoelectrical tomography techniques so as engineering geological surface mapping. In the paper we will present description of the Smrecje landslide, results of the conducted field investigations, so as designed remediation measures. Based on the remediation design, the remediation works were constructed in the spring 2009.