engleski

Kostanjek landslide: current state and planned project activities

Kostanjek landslide is placed in the hilly area of Mt. Medvednica, which belongs to western part of urban area of Zagreb city. This is the largest landslide in the area of Zagreb mainly caused by antropogene factor, i.e. mining of limestone and marl. Open pit mines are placed in the vicinity of upper part of landslide and in the lower part of landslide. Kostanjek landslide was activated in 1963 and excavation of marl was stoped in 1988 after identification of surface excavation in the toe of landslide as the triggering factor. Interpretation of landslide model and landslide causes was made by Ortolan (1989). Main elements of landslide model developed by Ortolan (1989) are the following: landslide area is 1.2 km2 ; total volume of displaced mass is 32.6 millions m3 ; three sliding surface are interpreted (at the depths 50 m, 65 m and 90 m) ; landslide is reactivated in the period of 26 years ; volume of second displacement was 12.8 millions m3 ; volume of third displacement was 7 millions m3. Initial displacement occurred along bedding planes of Sarmatian deposit composed of laminated marl. Subsequent reactivation was in upper part of landslide body composed of deposits of Panonian age (marl and clayey marl). Maximum displacement of particular parts at the landslide surface (in the period from 1963 to 1994) was 3.9 m. Consequently, landslide damaged approximately 500 residential and industrial buildings, and 100 of them are completely destroyed. Kostanjek landslide area is highly risky area because of existing and potential damages. Because of that, the City of Zagreb ordered design of remedial measures which is currently in progress. In the frame of Croatian-Japanese project, Kostanjek landslide is pilot area for establishment of integrated monitoring system using geodetic and geotechnical monitoring equipment (GPS, extensometers, inclinomteres, piezometers, pore pressuremeters, rain gauge, seismographs). Real time monitoring results will be base for establishment of early warning system. For the purpose of detailed planning of monitoring system it is necessary to define landslide border at the surface. In the case of Kostanjek landslide, landslide border is not clearly expressed. Moreover, damaged houses also exist outside landslide border interpreted by Ortolan (1989). Considering existing data and requirements of planned monitoring activities it is necessary to establish inventory of existing damages on houses and constructions in the form of GIS database.

Croatian-Japanese Bilateral Project; Kostanjek landslide

Prošireni sažetak bit će objavljen naknadno.