Embed Size (px)
Citation preview
413
ispitivanja bi trebala prethoditi bušenju i laboratorijskim ispitivanjima, a kao brža i jeftinija omogućiti racionalan i efikasan ukupni program istražnih radova. Njima se dobivaju podaci o svojstvima tla kontinuirano po dubini, odmah po završetku ispitivanja. Tijekom njihove provedbe moguće je na terenu usmjeravati i prilagođavati program istražnih radova stvarno zatečenim uvjetima i potrebama projekta te usmjeravati skupa istražna bušenja i ispravan odabir pozicija neporemećenih uzoraka.
Reference ASTM, 2001.,2007.,2015. D 6635-01 Standard Test Method for performing DMT, Book of Standards Volume 04.09, CEN-Eurocode 7 (1999)
Institut IGH d.d., Regionalni centar Osijek, 2018a. Geotehnički elaborat, oznaka evidencije 73220-5918-2018.
Institut IGH d.d., Zagreb, 2018b. Izvještaj o ispitivanju tla statičkim penetrometrom (CPTU), oznaka evidencije 72540-015/18.
International Organization for Standardization, 2012. EN ISO 22476-1:2012, Geotehničko istraživanje i ispitivanje,
Terensko ispitivanje, 1.dio: Ispitivanje električnim statičkim prodiranjem bez mjerenja pornog tlaka i s mjerenjem pornog tlaka
International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE), 2001. The Flat Dilatometer Test (DMT) in Soil Investigations, Report of the ISSMGE Technical Committee 16 on Ground Property Characterisation from In-situ Testing.
Marchetti,S., 1980. In Situ Tests by Flat Dilatometer. Jnl. American Society of Civil Engineers vol. 106 n. GT3. pp. 299-321.
Statom d.o.o. Našice, 2018. Izvještaj o geotehničkim istražnim radovima, ST-GE-05/18,
�Robertson, P.K., 1990. Soil classification using the cone penetration test, Canadian Geotechnical Journal. Vol 27, pp. 151-158.
Robertson P.K., 2009. Interpretation of Cone Penetration Tests – a unified approach, Canadian Geotechnical Journal, 46(11), pp. 1337-1355.
�Robertson, P.K., 2016. Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update. Canadian Geotechnical Journal, 53, pp. 1910-1927.
GEOTECHNICAL CHALLENGES IN KARST
ISRM Specialised Conference / Međunarodna konferencija 8. Savjetovanje Hrvatskog geotehničkog društva Omiš – Split, Croatia, 11.-13.04.2019. ISBN 978-953-95486-8-9
1 Budapest University of Technlogy and Economics,Budapest, [email protected]
2 University of Split, Faculty of Civil Engineering, Architecture and Geodesy, [email protected]
Comparative analysis of slope stability: seismic loading and engineering geology; examples from Croatia and Hungary
Usporedna analiza stabilnosti kosina na primjerima iz Hrvatske i Mađarske: seizmičko opterećenje i inženjerska geologija
Ákos TÖRÖK1, Goran VLASTELICA2, Goran BALOEVIĆ2, Nikola GRGIĆ2, Péter GÖRÖG1
Abstract The paper compares the engineering geological parameters of Croatian flysch deposits and Hungarian marls with respect to slope stability. Eocene flysch deposits are widespread sediments in Central Dalmatia. They form gentle to steep slopes in the countryside and in urban areas, with risks of slope instability. Especially weathered and long-time exposed open cuts are endangered. The rock mechanical parameters vary significantly: uniaxial compressive strength from 5 MPa (clayley marl) to 80 MPa (sandstone). In Hungary Eocene marl is common lithology in the broader area of Budapest. The mean UCS of clayey layers is 4-5 MPa, but calcareous marl has a UCS up to 45 MPa. Slope instability is pronounced by small-scale landslide in un-vegetated slopes and also on covered slopes of weathered marls. Besides laboratory analyses of rock mechanical parameters shake table tests are also possible to assess the seismic behaviour of these materials. Large scale laboratory tests can be used to analyse slope stability on small scale model.
Keywords: slope stability, flysch, marl, uniaxial compressive strength
Sažetak U radu se uspoređuju inženjersko-geološki parametri flišnih naslaga u Hrvatskoj i laporaca u Mađarskoj s obzirom na stabilnost kosina. Eocenske flišne naslage su rasprostranjeni sedimenti u Srednjoj Dalmaciji. Kosine u ovim materijalima su blagih i strmih nagiba, s izraženom podložnosti gubitku stabilnosti. Naročito su ugroženi rastrošeni i dugotrajni otvoreni zasjeci. Mehanički parametri stijena značajno variraju: jednoosna tlačna čvrstoća od 5 MPa (glinoviti lapor) do 80 MPa (pješčenjak). U Mađarskoj je eocenski lapor uobičajena litologija u širem području Budimpešte. Srednja jednoosna tlačna čvrstoća glinovitih slojeva iznosi 4-5 MPa, međutim karbonatni lapor ima UCS do 45 MPa. Nestabilnosti kosina se manifestiraju kao mala klizišta na padinama bez vegetacije, kao i na padinama pokrivenim rastrošenim laporom. Osim laboratorijskih analiza mehaničkih parametara stijena, moguće je i ispitivanje stabilnosti na potresnoj platformi. Za analizu stabilnosti kosina mogu se koristiti laboratorijska ispitivanja za analize stabilnosti kosina na skaliranom modelu.
Ključne riječi: stabilnost kosina, fliš, lapor, jednoosna tlačna čvrstoća
GEOTECHNICAL CHALLENGES IN KARSTISRM Specialised Conference / Međunarodna konferencija 8. Savjetovanje Hrvatskog geotehničkog društva Omiš – Split, Croatia, 11.-13.04.2019. ISBN 978-953-95486-8-9
1 Budapest University of Technlogy and Economics,Budapest, [email protected] University of Split, Faculty of Civil Engineering, Architecture and Geodesy, [email protected]
414 GEOTECHNICAL CHALLENGES IN KARST OMIŠ 2019.
Introduction Steep and gentle slopes of marls and alternating layers of clay and sandstone represent special landslide hazards since the behaviour of such highly heterogeneous material pacakges are still not fully understood. However, in the past years several studies dealt with the problem of heterogeneous rock masses (Marinos and Hoek 2001, Hoek et al. 2005). It has been demonstrated that the behaviour of such rock types strongly depend on the sedimentological characteristics, such as thickness of beds and alternations of harder and less consolidated beds, mineralogy and grade of weathering.
The present study provides a short outlook to the problem comparing two lithologies of heterogeneous rock masses: flysch and marl. The given examples are from Croatia and Hungary. The paper focuses on the properties of these rocks providing information on the laboratory test results. It also outlines the differences in the seismic behaviour of both flysch and marl with regard to the different seismicity of Croatia and Hungary.
Geological background The heterogeneous rock geological formations are common both in Croatia and Hungary, and are found not only in the higher mountainous areas, but also at low lying lands, hills and in coastal zones.
The most common lithotype responsible for landslides in Croatia are Eocene flysch deposits covering large areas in coastal part of Central Dalmatia (Fig. 1).
Figure 1. Geological map showing the occurrence of flysch deposits in Dalmatian region (after Mostecak et al. 2018).
While flysch deposits are common in Croatia (Vlastelica, 2015), Eocene marls have the same importance in terms of landslide hazard in Hungary (Görög and Török 2007). The calcareous marls are mostly located in Central part of Hungary and forms a part of the Priabonian transgressive system (Fig 2).
Figure 2. Distribution of the Eocene depositional systems in Hungary. Buda marl is found within the Priabonian transgression system marked by circled pattern (after Haas 2013).
Eocene marl (Buda Marl Formation) is at the surface especially Buda side of Budapest and in small zones of North Hungarian Mountains. Thus landslide affected areas are mostly found in Buda Hills region. Not only the Eocene marl but also the overlaying Oligocene clay (Görög 2007a) is prone to landslides at this part of Hungary.
Figure 3. Distribution of earthquakes in the Carpathian basin and its surroundings (red dots represent earthquake epicentres, and the size of the circle is proportional to magnitude, while the boundary of Hungary is marked in blue) (after Török 2007, data from Gerner et al. 1999).
The seismic activity in the two countries is different. Hungary belongs to the moderately active segment of the Carpathian basin (Fig 3.), while Croatia is
considered a more active part of the Carpatho-Dinaric region (Fig 4.).
Figure 4. Distribution of earthquakes in the Croatia from BC to 2008. (Herak et al 1996, updated by the Department of Geophysics, University of Zagreb).
Methods Samples were collected from Eocene flysch deposits of Croatia and of Eocene Buda Marl of Hungary. Rock mechanical parameters were measured under laboratory conditions on cylindrical specimens. The cylinders were either drilled from larger rock blocks or were cut from rotary drill cores. The laboratory tests were performed according to European Norms, and also by following ISRM guidelines. Bulk and material densities, ultrasonic pulse velocity, water absorption, uniaxial compressive strength and tensile strength were measured. Modulus of elasticity was also calculated. Air dry and water saturated specimens were prepared in order to model environmental conditions. Strength parameters were calculated by using Rocscience RockLab software.
Materials Dalmatian marls found in flysch strata are usually of bright yellow, grey, brown or bluish colour, while their stratification varies from a few centimeters to several meters (Fig. 5). Marl in Dalmatia is usually considered as a rock containing between 15
and 85% of clay, and 15 and 85% carbonate (CaCO3), and it can usually be found in Central Dalmatia in ranges of 40-80% CaCO3 (Vlastelica et al, 2018).
Figure 5. Dalmatian flysch (Vlastelica, 2015).
The major part of the calcite in Dalmatian marl is of chemical origin, i.e. developed by the extraction from the sea or lake water, and the small part is clastic.
The studied Hungarian marl forms a part of Eocene Buda Marl Formation. It is light grey predominantly calcareous marl (Fig. 6), which becomes yellowish at the surface due to weathering. It is thick-bedded to laminated. The carbonate content show some variations, but usually more than 40 % (Báldi 1983). Small amount of fine sand can be also detected in the marl sequence. Thus the lithologies can have a wide range from calcareous marl to clay marl.
Figure 6. Light grey calcareous marl (drilling core from Buda castle hill, Budapest).
In some layers pyrite can occur, which than transforms to limonite-goethite at the surface. This transformation also contribute to the colour change of the marl and thus at the surface and close to the surface in the weathered zone most marls are yellowish brown (Fig. 7). The differences in lithologies
415
Introduction Steep and gentle slopes of marls and alternating layers of clay and sandstone represent special landslide hazards since the behaviour of such highly heterogeneous material pacakges are still not fully understood. However, in the past years several studies dealt with the problem of heterogeneous rock masses (Marinos and Hoek 2001, Hoek et al. 2005). It has been demonstrated that the behaviour of such rock types strongly depend on the sedimentological characteristics, such as thickness of beds and alternations of harder and less consolidated beds, mineralogy and grade of weathering.
The present study provides a short outlook to the problem comparing two lithologies of heterogeneous rock masses: flysch and marl. The given examples are from Croatia and Hungary. The paper focuses on the properties of these rocks providing information on the laboratory test results. It also outlines the differences in the seismic behaviour of both flysch and marl with regard to the different seismicity of Croatia and Hungary.
Geological background The heterogeneous rock geological formations are common both in Croatia and Hungary, and are found not only in the higher mountainous areas, but also at low lying lands, hills and in coastal zones.
The most common lithotype responsible for landslides in Croatia are Eocene flysch deposits covering large areas in coastal part of Central Dalmatia (Fig. 1).
Figure 1. Geological map showing the occurrence of flysch deposits in Dalmatian region (after Mostecak et al. 2018).
While flysch deposits are common in Croatia (Vlastelica, 2015), Eocene marls have the same importance in terms of landslide hazard in Hungary (Görög and Török 2007). The calcareous marls are mostly located in Central part of Hungary and forms a part of the Priabonian transgressive system (Fig 2).
Figure 2. Distribution of the Eocene depositional systems in Hungary. Buda marl is found within the Priabonian transgression system marked by circled pattern (after Haas 2013).
Eocene marl (Buda Marl Formation) is at the surface especially Buda side of Budapest and in small zones of North Hungarian Mountains. Thus landslide affected areas are mostly found in Buda Hills region. Not only the Eocene marl but also the overlaying Oligocene clay (Görög 2007a) is prone to landslides at this part of Hungary.
Figure 3. Distribution of earthquakes in the Carpathian basin and its surroundings (red dots represent earthquake epicentres, and the size of the circle is proportional to magnitude, while the boundary of Hungary is marked in blue) (after Török 2007, data from Gerner et al. 1999).
The seismic activity in the two countries is different. Hungary belongs to the moderately active segment of the Carpathian basin (Fig 3.), while Croatia is
considered a more active part of the Carpatho-Dinaric region (Fig 4.).
Figure 4. Distribution of earthquakes in the Croatia from BC to 2008. (Herak et al 1996, updated by the Department of Geophysics, University of Zagreb).
Methods Samples were collected from Eocene flysch deposits of Croatia and of Eocene Buda Marl of Hungary. Rock mechanical parameters were measured under laboratory conditions on cylindrical specimens. The cylinders were either drilled from larger rock blocks or were cut from rotary drill cores. The laboratory tests were performed according to European Norms, and also by following ISRM guidelines. Bulk and material densities, ultrasonic pulse velocity, water absorption, uniaxial compressive strength and tensile strength were measured. Modulus of elasticity was also calculated. Air dry and water saturated specimens were prepared in order to model environmental conditions. Strength parameters were calculated by using Rocscience RockLab software.
Materials Dalmatian marls found in flysch strata are usually of bright yellow, grey, brown or bluish colour, while their stratification varies from a few centimeters to several meters (Fig. 5). Marl in Dalmatia is usually considered as a rock containing between 15
and 85% of clay, and 15 and 85% carbonate (CaCO3), and it can usually be found in Central Dalmatia in ranges of 40-80% CaCO3 (Vlastelica et al, 2018).
Figure 5. Dalmatian flysch (Vlastelica, 2015).
The major part of the calcite in Dalmatian marl is of chemical origin, i.e. developed by the extraction from the sea or lake water, and the small part is clastic.
The studied Hungarian marl forms a part of Eocene Buda Marl Formation. It is light grey predominantly calcareous marl (Fig. 6), which becomes yellowish at the surface due to weathering. It is thick-bedded to laminated. The carbonate content show some variations, but usually more than 40 % (Báldi 1983). Small amount of fine sand can be also detected in the marl sequence. Thus the lithologies can have a wide range from calcareous marl to clay marl.
Figure 6. Light grey calcareous marl (drilling core from Buda castle hill, Budapest).
In some layers pyrite can occur, which than transforms to limonite-goethite at the surface. This transformation also contribute to the colour change of the marl and thus at the surface and close to the surface in the weathered zone most marls are yellowish brown (Fig. 7). The differences in lithologies
416 GEOTECHNICAL CHALLENGES IN KARST OMIŠ 2019.
are also reflected in the physical properties as it was pointed out earlier (Görög 2007b).
Figure 7. Light brownish yellow weathered near surface zone of marl (from a pit at Buda castle hill, Budapest).
Results and discussion The physical properties of the Croatian Eocene marls found in flysch can vary significantly (Table 1) and it reflects the variations in the lithologies. Most tipical occuring are marls in range 45-65% CaCO3 (Vlastelica et al., 2016).
Table 1. Physical properties of Dalmatian flysch (range, in general, Šestanović, 1989) and typical Dalmatian marls (typical values in 45-65% CaCO3 range).
Property Flysch (in general) Marl
Density [kg/m3]
2000-2800 2300
US pulse velocity [km/s]
0.5-4.0 2.0
Uniaxial Comp. Str [MPa] 6.2 – 79.5 15
Modulus of elasticity [GPa]
2-5 3
Tensile strenght [MPa] 0.8-6.5 N/A
The physical properties of the Hungarian Eocene marl reflect the variations in the lithologies. Calcareous marl has much higher strength than the clayey marl (Table 2). Namely the mean uniaxial compressive strength of the calcareous marl is more than eight times higher than that of the clayey marl. The differences in strength are also
reflected in the indirect tensile strength, but the difference is only triple in that case. The differences in strength of various marl lithologies were also documented earlier (Görög 2007). Ultrasonic pulse velocity data of calcareous marl and clayey marl do not differ that much.
Table 2. Physical properties of Hungarian Eocene marl lithologies: calcareous marl and clayey marl (mean values) (partly based on Görög 2007b and Török 2007).
Property Calcareous
marl Clayey
marl Density [kg/m3] 2475 2289
US pulse velocity [km/s]
2.60 1.65
Uniaxial Comp. Str [MPa]
44.3 5.5
Modulus of elasticity [GPa]
7.38 0.52
Tensile strenght [MPa]
4.4 1.4
Comparing the physical properties of the Croatian flysch and the Hungarian marls, it is clear that there are significant differences within one Formation. There are some lithological overlaps between the Croatian flysch and the Hungarian marl. Namely; in both formations marly layers are found. According to the test result all the measured properties (density, US pulse velocity, UCS, Young’s modulus) of the marl from Dalmatia is between the Hungarian calcareous and clayey marl (Table 1 and Table 2). The average value of the Young’s modulus of the Dalmatian marl is less than half of the Hungarian calcareous marl, but more than two times higher than the clayey marl. The test results reflect the differences in lithologies. The higher the carbonate content of the Hungarian marl, the higher the strength of the marl.
In terms of seismic behaviour the two heterogeneous formations the flysch and the marl have similar behaviour. Namely, the slopes that are characterized by the abundance of higher strength lithologies are less prone to seismically induced deformations, and to landslides. However sudden earthquakes can trigger rock falls,
when the highly cemented lithologies are fractured and tectonically deformed. The rock fall hazard of such slopes can be assessed by using physical properties (Crosta & Agliardi 2003) or by modelling of the trajectories of falling blocks (Samodra et al. 2016). Steeper cliff faces can be formed naturally or by human activity from these lithologies. To assess the seismic stability of these cliff faces additional data is needed: such as slope profile, joint pattern, block size (De Biagi et al. 2017).
Shake table - testing possibilities Besides laboratory analyses of rock mechanical parameters, actual behaviour and stability of slopes under an earthquake is still insufficiently investigated area and subject of researches (for example Hong et al. 2005, Shinoda et al. 2013). The experimental study on the behaviour and stability of slopes under seismic (earthquake) loading is planned to be conducted within Laboratory for Seismic Testing at University of Split in Croatia. The Laboratory is equipped with a shake-table with layout size of 4 × 4 m and maximal capacity of 20 tons (see Fig 8)..
Figure 8. Testing of a specimen at Laboratory for Seismic Testing (Banovic et al 2018)
The shake-table can achieve maximal displacement of approximately 150 mm, maximal acceleration of up to 5 g, and frequencies up to 20 Hz (Baloević et al. 2017). The tests are conducted on scaled models, with variation of several parameters, such as: slope height, slope angle, granulometry, earthquake type, peak ground acceleration etc. The results obtained from shake-table tests can be useful tool to access the actual seismic behaviour of slopes in seismic areas.
Conclusions The rock mechanical parameters vary significantly of Croatian flysch and Hungarian marl. In the flysch cemented sandstone layers have the highest uniaxial compressive strength (in range of 80 MPa), while in the marl calcareous marls have the highest UCS values (44 MPa) that is comparable to the flysch sandstone. In the flysch the grain size and cementation, while in the marl the carbonate content are responsible for the high strength. The slope stability of these heterogeneous layers is controlled by the amount of low strength layers (marls in the Croatian flysch and clays in the Hungarian marl). The earthquake related hazards of slopes that are composed of highly cemented high strength lithologies also depend on other parameters besides strength. A few to mention are the joint system, block size and slope geometry. The earthquake hazard of the two countries are different thus in Croatia where high magnitude earthquakes are more common, the potential risk of earthquake triggered slope instability is higher.
Acknowledgments The research reported in this paper was partly supported by the Higher Education Excellence Program of the Ministry of Human Capacities in the frame of the Water Sciences & Disaster Prevention research area of BME (BME FIKP-VÍZ).
417
are also reflected in the physical properties as it was pointed out earlier (Görög 2007b).
Figure 7. Light brownish yellow weathered near surface zone of marl (from a pit at Buda castle hill, Budapest).
Results and discussion The physical properties of the Croatian Eocene marls found in flysch can vary significantly (Table 1) and it reflects the variations in the lithologies. Most tipical occuring are marls in range 45-65% CaCO3 (Vlastelica et al., 2016).
Table 1. Physical properties of Dalmatian flysch (range, in general, Šestanović, 1989) and typical Dalmatian marls (typical values in 45-65% CaCO3 range).
Property Flysch (in general) Marl
Density [kg/m3]
2000-2800 2300
US pulse velocity [km/s]
0.5-4.0 2.0
Uniaxial Comp. Str [MPa] 6.2 – 79.5 15
Modulus of elasticity [GPa]
2-5 3
Tensile strenght [MPa] 0.8-6.5 N/A
The physical properties of the Hungarian Eocene marl reflect the variations in the lithologies. Calcareous marl has much higher strength than the clayey marl (Table 2). Namely the mean uniaxial compressive strength of the calcareous marl is more than eight times higher than that of the clayey marl. The differences in strength are also
reflected in the indirect tensile strength, but the difference is only triple in that case. The differences in strength of various marl lithologies were also documented earlier (Görög 2007). Ultrasonic pulse velocity data of calcareous marl and clayey marl do not differ that much.
Table 2. Physical properties of Hungarian Eocene marl lithologies: calcareous marl and clayey marl (mean values) (partly based on Görög 2007b and Török 2007).
Property Calcareous marl
Clayey marl
Density [kg/m3] 2475 2289
US pulse velocity [km/s]
2.60 1.65
Uniaxial Comp. Str [MPa]
44.3 5.5
Modulus of elasticity [GPa]
7.38 0.52
Tensile strenght [MPa]
4.4 1.4
Comparing the physical properties of the Croatian flysch and the Hungarian marls, it is clear that there are significant differences within one Formation. There are some lithological overlaps between the Croatian flysch and the Hungarian marl. Namely; in both formations marly layers are found. According to the test result all the measured properties (density, US pulse velocity, UCS, Young’s modulus) of the marl from Dalmatia is between the Hungarian calcareous and clayey marl (Table 1 and Table 2). The average value of the Young’s modulus of the Dalmatian marl is less than half of the Hungarian calcareous marl, but more than two times higher than the clayey marl. The test results reflect the differences in lithologies. The higher the carbonate content of the Hungarian marl, the higher the strength of the marl.
In terms of seismic behaviour the two heterogeneous formations the flysch and the marl have similar behaviour. Namely, the slopes that are characterized by the abundance of higher strength lithologies are less prone to seismically induced deformations, and to landslides. However sudden earthquakes can trigger rock falls,
when the highly cemented lithologies are fractured and tectonically deformed. The rock fall hazard of such slopes can be assessed by using physical properties (Crosta & Agliardi 2003) or by modelling of the trajectories of falling blocks (Samodra et al. 2016). Steeper cliff faces can be formed naturally or by human activity from these lithologies. To assess the seismic stability of these cliff faces additional data is needed: such as slope profile, joint pattern, block size (De Biagi et al. 2017).
Shake table - testing possibilities Besides laboratory analyses of rock mechanical parameters, actual behaviour and stability of slopes under an earthquake is still insufficiently investigated area and subject of researches (for example Hong et al. 2005, Shinoda et al. 2013). The experimental study on the behaviour and stability of slopes under seismic (earthquake) loading is planned to be conducted within Laboratory for Seismic Testing at University of Split in Croatia. The Laboratory is equipped with a shake-table with layout size of 4 × 4 m and maximal capacity of 20 tons (see Fig 8)..
Figure 8. Testing of a specimen at Laboratory for Seismic Testing (Banovic et al 2018)
The shake-table can achieve maximal displacement of approximately 150 mm, maximal acceleration of up to 5 g, and frequencies up to 20 Hz (Baloević et al. 2017). The tests are conducted on scaled models, with variation of several parameters, such as: slope height, slope angle, granulometry, earthquake type, peak ground acceleration etc. The results obtained from shake-table tests can be useful tool to access the actual seismic behaviour of slopes in seismic areas.
Conclusions The rock mechanical parameters vary significantly of Croatian flysch and Hungarian marl. In the flysch cemented sandstone layers have the highest uniaxial compressive strength (in range of 80 MPa), while in the marl calcareous marls have the highest UCS values (44 MPa) that is comparable to the flysch sandstone. In the flysch the grain size and cementation, while in the marl the carbonate content are responsible for the high strength. The slope stability of these heterogeneous layers is controlled by the amount of low strength layers (marls in the Croatian flysch and clays in the Hungarian marl). The earthquake related hazards of slopes that are composed of highly cemented high strength lithologies also depend on other parameters besides strength. A few to mention are the joint system, block size and slope geometry. The earthquake hazard of the two countries are different thus in Croatia where high magnitude earthquakes are more common, the potential risk of earthquake triggered slope instability is higher.
Acknowledgments The research reported in this paper was partly supported by the Higher Education Excellence Program of the Ministry of Human Capacities in the frame of the Water Sciences & Disaster Prevention research area of BME (BME FIKP-VÍZ).
418 GEOTECHNICAL CHALLENGES IN KARST OMIŠ 2019.
References Baloević, G., Radnić, J., Grgić, N., Matesan, D., 2017. Shake-table study of plaster effects on the behavior of masonry-infilled steel frames. Steel and Composite Structures 23(2): pp. 195-204.
Banović, I., Radnić, J., Grgić, N., 2018. Shake Table Study on the Efficiency of Seismic Base Isolation Using Natural Stone Pebbles (2018) Advances in Materials Science and Engineering, art. no. 1012527,
Báldi T 1983. Oliogocene and Lower Miocene Formations in Hungary (Magyarországi oligocén és alsómiocén formációk). Akadémia Kiadó, Budapest, (in Hungarian).
Crosta, G.B., Agliardi, F. 2003. A methodology for physically based rockfall hazard assessment. Nat. Hazards Earth Syst. Sci., 3: pp. 407–422.
De Biagi, V., Napoli, M.L., Barbero, M., and Peila, D. 2017. Estimation of the return period of rockfall blocks according to their size. Nat. Haz. Earth Syst. Sci., 17: pp. 103–113,
Gerner P., Bada G., Dövényi P., Müller B., Oncescu, M.C., Cloething, S., Horváth, F. 1999. Recent tectonic stress and crustal deformation in and around the Pannonian Basin: data and models. In: Durand, B. et al (eds.) The Mediterranean basins: Tertiary extension with the Alpine orogen. Geological Society London, Special Publications 156, pp. 269-294.
Görög P. 2007a. Engineering geologic properties of the Oligocene Kiscell Clay. Central European Geology, 50(4): pp. 313-329.
Görög P. 2007b. Characterization and mechanical properties of Eocene Buda Marl. Central European Geology 50(3): pp. 241-258.
Görög P., Török Á. 2007. Slope stability assessment of weathered clay by using field data and computer modelling: a case study from Budapest. Nat. Hazards Earth Syst. Sci., 7, pp. 417–422
Haas J. 2013. Geology of Hungary, Springer, Berlin, 1-246
Herak, M., Herak, D., Markušić, S. 1996., Revision of the earthquake catalogue and seismicity of Croatia, 1908–1992, Terra Nova, 8 (1): 86-94
Hoek, E. Marinos, P, Marinos, V. 2005. Characterization and engineering properties of tectonically undisturbed but lithologically varied sedimentay rock masses. Int. J. Rock Mech. Min. Sci. 42: pp. 277-285
Hong, Y.S., Chen, R.H., Wu, C. S., Chen, J.R. 2005. Shaking table tests and stability analysis of steep nailed slopes. Canadian Geotechnical Journal, 42 (5), pp. 1264-1279.
Marinos, P., Hoek, E. 2001. Estimating the geotechnical properties of heterogenous rock masses such as flysch. Bull. Eng. Geol. Env. 60: 82-92.
Mostečak, A, Perković, D, Kapor F. Veinovic, Z 2018. Radon mapping in Croatia and its relation to geology. Rudarsko-geološko-naftni zbornik. 33. pp. 1-11.
Samodra, G., Chen, G., Sartohadi, J., Hadmoko, D.S., Kasama, K., and Setiawan, M.A. 2016. Rockfall susceptibility zoning based on back analysis of rockfall deposit inventory in Gunung Kelir, Java. Landslides, 13, pp. 805–819,
Šestanović S. 1989. Inženjersko-geološka istraživanja fliša u istočnim stambenim naseljima Splita. RGN zbornik (1), pp. 69-76.
Shinoda M., Nakajima S., Nakamura H., Kawai T., Nakamura S. 2013. Shaking table test of large-scaled slope model subjected to horizontal and vertical seismic loading using E-Defense, Proc. of the 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris.
Török Á. 2007. Geology for Engineers. Műegyetemi Kiadó, Budapest, 1-384 (in Hungarian with English abstract)
Vlastelica, G. 2015. The Influence of Weathering on Durability of Cuts in Soft Rock Mass. Split: University of Split, FCEAG. PhD thesis.
Vlastelica, G., Miščević, P., Pavić, N., 2016. Testing the shear strength of soft rock at different stages of laboratory simulated weathering. Gradevinar, 68 (12), pp. 955-966.
Vlastelica, G., Miščević, P., Štambuk Cvitanović, N. 2018. Durability of soft rocks in Eocene flysch formation (Dalmatia, Croatia), Engineering. Geology 245, pp. 207-217.
GEOTECHNICAL CHALLENGES IN KARST
ISRM Specialised Conference / Međunarodna konferencija 8. Savjetovanje Hrvatskog geotehničkog društva Omiš – Split, Croatia, 11.-13.04.2019. ISBN 87587655865
1 Budapest University of Technlogy and Economics,Budapest,
B. Vásárhelyi: [email protected];
D. Kovács: [email protected]; Á. Török: [email protected]
Complex investigation and analysis of a rock slope using different empirical methods
Kompleksno istraživanje i analiza kosina u stijeni primjenom različitih empirijskih metoda
Balázs VÁSÁRHELYI1, Dorottya KOVÁCS1, Ákos TÖRÖK1
Abstract Nearly 30 m high rock slope construction was necessary in soft rock condition during the construction of main road No. 21 in Hungary. Using rock mechanical laboratory test results, two different empirical rock classes (Slope Mass Rating – SMR and Q-slope) were applied to calculate the stability of the rock slope. For these calculations, the angles between the fracture geometries and the geometry of the rock cut should be taken into account to assume both very favourable and very unfavourable conditions. The analysis have shown that in unfavourable conditions the slope may be affected by sliding and a significant deterioration of the slope’s rock material may occur due to weathering.
Keywords: rock slope, stability calculation, Slope Mass Rating, Q-slope value, Geological Strength Index
Sažetak Tijekom izgradnje glavne ceste br. 21 u Mađarskoj bilo je potrebno izgraditi gotovo 30 m visoke zasjeke u mekoj stijeni. Koristeći rezultate laboratorijskih ispitivanja stijena, primijenjene su dvije različite empirijske klasifikacije stijena (Slope Mass Rating - SMR i Q-slope) za izračun stabilnosti kosina u stijeni. Za te izračune treba uzeti u obzir kutove loma stijene i geometrije zasijecanja stijene kako bi se pretpostavili vrlo povoljni i vrlo nepovoljni uvjeti. Analiza je pokazala da u nepovoljnim uvjetima kosina može biti podložna klizanju i može doći do značajnog pogoršanja stijenskog materijala zbog atmosferskih utjecaja.
Ključne riječi: kosina u stijeni, proračun stabilnosti, Slope Mass Rating, Q-slope, indeks geološke čvrstoće
Introduction During the reconstruction of the main road No. 21 in northern Hungary (Fig. 1) -which is runs between Hatvan and Somoskőújfalu in the valley of the Zagyva River-, a nearly 30 m high rock slope was designed. Nearly 2 km long section of this road is running in a narrow valley between the river and the
east side of the Cserhát Mountain. For designing the rock slope the following complex methods were used:
- Two boreholes were drilled in the investigated area. Due to difficult access to the site it was impossible to drill more.
- Rock mechanical laboratory tests were carried out to determine the mechanical
