bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability evaluation of cut slopes in highly weathered schists using limit equilibrium, kinematical and empirical methods
Authors: Janevski B , Jovanovski M 
Published: September 2021

1. Extended abstract
The traditional limit equilibrium method and the kinematic analyses are the first choices in the geotechnical practice for the assessment of the slope stability of a particular rock slope. The reason is that very few empirical methods exist for this purpose.
This paper presents results of the slope stability assessment with limit equilibrium, kinematical and empirical methods for over 50 deep cut slopes in highly weathered schists along the A2 motorway section Kicevo-Ohrid in RN Macedonia. The research area is mainly composed of phyllite, sericite schists, quartz-sericite schists and graphitic schists. These rocks are highly weathered, tectonically disturbed and often folded, which means they are prone to local deformations, especially in aspects of the long-term impact of atmospheric influences and the existence of unfavourable joint sets. Although most of the failures that occurred had local character, on several cut slopes global failure occurred. The slope stability assessment of the subject rock formations is a difficult challenge because the highly weathered phyllite and schists are difficult to be characterised, considering the uncertainties associated with the material anisotropy and the network of discontinuities.
This study employs different failure mechanisms of cut slope stability in complex geological media. The rock masses were modelled according to the generalized Hoek-Brown criterion while the joints behaviour was modelled using the Barton-Bandis shear strength criterion. Rocscience software package was used for executing the limit equilibrium analyses and the stability analyses along discontinuities. The relatively new and intuitive empirical method Q-slope was applied for the stability assessment of the excavated rock slopes.
According to the results and the findings, it can be emphasized that although the limit equilibrium analyses showed relatively stable slopes, significant failures on several cut slopes occurred on site. The stability conditions on site were confirmed with the kinematical analyses and the Q-slope method.
The final decision of the slope geometry should be made after the inspection of the excavated surfaces because it is very difficult to register the discontinuity conditions before the construction phase starts. The best way to assess the stability condition is with a combination of different tools and methodologies, especially when we face highly weathered rock formations.
The next step of this research will be to propose a methodology, where the long-term rock slope stability and the associated level of risk will be evaluated using graphical diagrams.
An Overview of carbonate complex characteristics on dam sites along The Neretva River
Authors: Jazvin E , Ćpago A , Jovanovski M 
Published: September 2021

1. Extended abstract
An extensive inventory of engineering rock properties presents an essential feature for characterization of the site which is of vital importance for engineering activities. Geotechnical modelling is a highly sophisticated procedure that considers number of influential factors on rock mass conditions and properties which are of particular interest in design of large, capital buildings. In specific geological environments, such as karst, it is practically impossible to obtain specific design parameters without multidisciplinary approach that involves experts in various fields (engineers, hydrologists, geologists, speleologist) coupled with the application of available technologies and methods to survey the site and foreseen possible risks for the project.
Carbonate complexes are present in the maritime and central belt of the Dinaric Alps through which Neretva River flows. In river’s central basin, Salakovac and Grabovica hydroelectric gravity dams were constructed, the case study sites analysed in this paper. In this area, numerous field and laboratory tests of mechanical and dynamic properties had been carried out. The current work is a continuation of previous studies conducted by Selimoviæ (2004) and further deepened by pago (2010) and related publications and aims to provide an overview of the practice and methods, highlight common issues and risks of designing and building in karst and to draw the lines among a spectra of rock characterization parameters used to describe carbonate complexes in Neretva River area.
Validated regression models that examine the correlation between rock properties were used to create clusters of rock mass quality and the corresponding values for static and dynamic parameters to enable faster yet sufficiently accurate input data for geotechnical modelling process for initial project stages. With each construction project in the surrounding, given dataset should be supplemented with newly obtained data that would improve the accuracy of the model and open an opportunity for development of new model types to make geotechnical analysis more reliable while deepening the understanding on local conditions for designing and building in the karst areas of Neretva.
A Modern Approach in Analyzing and Designing of Rockfall Protection Measures: The City of Omiš Rockfall Protection Case Study
Authors: Peranić J , Prodan M Vivoda , Jovančević S Dugonjić , Udovič D , Arbanas S Mihalić , Gazibara S Bernat , Krkač M , Arbanas Ž 
Published: September 2021

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.
The importance of accounting for matedness when predicting the peak shear strength of rock joints
Authors: Ríos-Bayona F , Andersson E , Johansson F , Mas Ivars D 
Published: September 2021

Abstract
The contribution from both surface roughness and matedness in the peak shear strength of rock joints is not yet well understood. To be able to account for the influence of matedness on the peak shear strength of rock joints, both surface roughness and aperture need to be considered. Technical developments over the past few decades have shown that both surface roughness and aperture can be accurately measured using optical scanning. This technique has been utilized to account for surface roughness parameters in various shear strength criteria that assume a perfect match between joint surfaces. This paper investigates and compares the capabilities of two shear strength criteria to predict the peak shear strength of rock joints with different matedness. The analysis performed shows that both approaches have their strengths and limitations. For instance, accounting for the matedness of unmated rock joints based on their surface aperture gives better predictions of the peak shear strength. On the other hand, accounting for shearing failure mode becomes relevant at high normal loads. A possible way forward to reduce the limitations of these criteria could be to combine their strengths.
Measuring Carbonate Rock Strength using Spectroscopy across the Optical and Thermal Region
Authors: Bakun-Mazor D. , Ben-Ari Y. , Notesko G. , Marco S. , Ben-Dor E. 
Published: September 2021

Abstract
We seek to define new empirical relations between the spectral signature of rock surfaces and their geomechanical characteristics. By this means, proxy tools can be developed to classify the quality of rock masses in situations where access is restricted or impossible. In rock mechanics research, remote sensing technologies are mainly used for mapping surface geometry and rock discontinuities. However, the characterization of intact rock’s mechanical properties via remote sensing is a technique that has not yet been developed. In this study, spectral information is implemented using optical and thermal spectral regions. This technique enables identifying and recognizing objects based on the spectral absorption features of specific chemical attributes. In general, spectral acquisition of rocks can be done using stationary or moving (airborne) platforms. Assuming the chemical and physical attributes of rocks correlate to the material physical and chemical properties we find the spectral-based model for assessing rock strength remotely. As part of a preliminary proof-of-concept stage, we collected multiple cylindrical samples of different carbonate formations from several rock outcrops in Israel. We used point and imaging hyperspectral remote sensors to measure the surfaces of the samples in the visible and infrared regions. We determined the uniaxial compressive strength of the rock samples and analyzed them, to generate a model describing the strength of the samples, solely from spectral readings at both ranges. In addition, we conducted in-situ measurements of rock strength using a Schmidt hammer and rock surface spectra in the visible region on rock outcrops. The results of this pioneering study show that the correlation between carbonated rock strength and its spectral signatures enabled the remote assessment of the carbonate rock strength and led the way to an airborne remote sensing application. We continue to extend the database and further refine the analytical method, using this to establish a solid spectral-based model to depict rock strength remotely through exploiting the hyperspectral technology from stationary and airborne platforms.
Using non-destructive testing to assess static elastic modulus of a limestone exposed to high temperatures
Authors: Garrido M E , M-Ibáñez V , Signes C H , Tomás R 
Published: September 2021

Abstract
The determination of static elastic modulus in the laboratory requires rock core extraction and the subsequent testing of the samples by means of standardised uniaxial compressive strength tests. However, this destructive procedure is not always suitable – as in the case of protected historic buildings. In these cases, the static elastic modulus can be obtained from the dynamic elastic modulus, in turn derived from the velocity of ultrasonic waves (a non-invasive and non-destructive test). The relationship between both the dynamic and static moduli of rocks has been extensively addressed in the scientific literature. Furthermore, several researchers have separately studied the evolution of static or dynamic elastic moduli of rocks exposed to high temperatures – although few studies have compared both values. It is well known that the dynamic modulus is generally higher than the static modulus, and the values diverge especially in rocks with a low modulus of elasticity. These differences can be mainly explained by the effect of porosity and the size of cracks in the determination of both parameters. In this research, the relationship between static and dynamic moduli for ‘Borriol’ limestone is studied for samples previously subjected to 200, 400, 600 and 800 °C and then cooled slowly (in air) or quickly (immersed in water). The results show that the static modulus of samples heated up to 600 °C decreased 80.9 and 79.1 % and dynamic modulus decreased 62.5 and 64.8 % for slow and quick cooling samples, respectively. For samples heated to 600 and 800 °C, the static and dynamic moduli are similar. In general, no significant differences between both cooling methods are observed, even though static modulus shows more loss than dynamic modulus. Finally, linear models were used to correlate static and dynamic moduli, providing coefficients of determination of 0.99 and 0.97, for slow and quick cooling, respectively. It is also remarkable that the Edyn/Est rate was smaller than 1 for elastic moduli over 30 GPa (i.e., 105, 200 and 400 °C) and greater than 1 for lower moduli (i.e., 600 and 800 °C). The results obtained can be used to calculate the static elastic modulus of ‘Borriol’ limestone from dynamic modulus determined by non-destructive techniques.
Evaluation of the basic friction angle in dry and conditioned fluids by tilt tests
Authors: Beyhan S , Özdemir M 
Published: September 2021

AbstractThe basic friction angle is a basic parameter used in the shear strength estimation of discontinuities. The accurate determination of the shear strength of the discontinuities is of great importance for engineering structures built on or inside the rock.In this study; the variation of the basic friction angle tests under dry and different fluid conditions were carried out. For this purpose, a tilt device was designed. 7 different types of travertine samples with dimensions of 10×10×2 cm were used in the experiments. Tilt tests; to determine the change of the basic friction angle under different liquid conditions, dry, pH2, pH7 and pH12 were carried out under different test fluid conditions. Basic friction angles were measured 5 times in each group experiment. Initial basic friction angles were high regardless of sample type and experimental conditions. But; as the measurements continued, significant changes were observed about slip angles. The lowest basic friction angle was obtained in samples conditioned with pH2 while the highest angle was obtained in samples with ph7 conditioned. Thus, the effect of different water contents on sliding surfaces was determined experimentally. It is thought that this study can contribute to the existing studies on the basic friction angle with the tilt test.
Photoelastic stress analysis of mode I fracture toughness tests using PMMA samples
Authors: Muñoz-Ibáñez A , Herbón-Penabad M , Delgado-Martín J 
Published: September 2021

Abstract
Rocks are usually inhomogeneous and anisotropic materials. The presence of foliation planes, grain boundaries or even microcracks may alter the stress distribution. In order to identify whether unusual behaviours in rocks are due to these imperfections or result from other factors (e.g. experimental configuration), the analyses of homogenous and isotropic materials is an useful approach. We have performed a series of mode I fracture toughness (KIC
) tests using polymethyl methacrylate (PMMA) samples, which has the advantage of allowing photoelastic stress analysis based on its birefringent nature. Three different testing configurations were considered in the study: S\ emi-circular bend (SCB) test, the pseudo-compact tension (pCT) test, and a new alternative configuration based on the previous two that we have called pseudo-SCB (pSCB) test. To perform the photoelastic analysis, all the experiments were complemented with a specially-designed experimental setup consisting in two orthogonally arranged circular polarizers placed on both sides of the tested specimens. Using a source of white (polychromatic) light on one end it is possible to record the stress distribution using a digital camera aligned with the samples on the other end. As the load increases, a distinct evolving pattern of colour fringes can be visualized in the samples illustrating the spatially distributed stress levels. Based on this analysis we observe in some of the tests performed non-symmetrical stress fields. Although this behaviour could be related with the testing configuration, results suggest that other features, such as the shape of the notch tip, imperfections in sample preparation, or the misalignment of the samples in the testing device may also have an influence in stress distribution.
Estimation of crack initiation and crack damage stress by means of mechanical, physical and dynamical properties in brecciated marbles
Authors: Kotsanis D , Nomikos P , Rozos D , Perraki M 
Published: September 2021

Abstract
The objective of this study is the determination of the various stages of deformation of brecciated marbles, under uniaxial compression, and the application of regression techniques, to investigate the relations of these stages, with physical, dynamical, and mechanical properties. Therefore, a total number of fifteen specimens, prepared from samples obtained from various locations from the southern part of the East Attica Prefecture, Greece. The laboratory program involved the determination of the uniaxial compressive strength (UCS), the crack initiation (Cci) and crack damage stress (Ccd) levels, the static elastic modulus (Es), as well as the basic physical and dynamical properties, such as the dry density (γd), the effective porosity (neff) and the ultrasonic velocities of both primary (VP) and secondary (VS) waves. Results obtained from the mechanical tests reveal that the onset of stable (Cci) and unstable (Ccd) crack growth varies between 0.19–0.38 and 0.66–0.92 of the UCS values, respectively. Applying simple nonlinear regression models, it was found that crack initiation and crack damage stresses, decrease exponentially with the increase of effective porosity, while increase exponentially with the increase of static elastic modulus, dynamic elastic modulus (Ed), and the primary wave velocity.
Stability assessment of obliquely-bedded rock cuts using multi-prong procedures – case study
Authors: Spyropoulos E , Nawaz B , Ojo A , Ahmed H R , Waheed M A 
Published: September 2021

Abstract
The stability of vertical cuts in rocky strata, associated with the provision of the transportation infrastructure through a mountainous terrain, is always a challenge for the geotechnical engineers. The problem becomes further complex if the cuts are parallel or near parallel to the bedding planes. Such a scenario results in all sorts of slope instability scenarios, including planar, wedge, rockfall, and toppling failure. A linear project was planned to pass through the mountainous stretches of western Saudi Arabia. The rock slopes exposed at the site after the excavations constitute igneous origin Granite/Granodiorite rock present in a moderately to highly weathered state and consist of two sets of discontinuities; one running almost parallel to slope faces and another nearly orthogonal to the major set of discontinuities. Based on the orientation of the discontinuities along the cuts on both the sides of the excavation, there is a high probability of all types of slope failures, including planar, wedge, toppling, or boulder/rockfall. This paper presents details of geologic field mapping, field and laboratory testing, and the software analysis of several modes of the possible slope failure modes. The study was carried out considering all the potential triggering factors, including rainfall, under both static and dynamic/seismic conditions. The paper also discusses the slope failure prevention measures recommended based on the interpretation of the field and laboratory data, software analysis, and the construction sequence.
Determination of frictional resistance pair Jr/Ja using a friendly – graphical approach in the Q-slope empirical method
Authors: Borja-Bernal C P , Jordá-Bordehore y L 
Published: September 2021

Abstract
The Q-slope index is a new geomechanical classification for slope [1] that has become popular and is spreading throughout the world. It is currently being applied in various lithologies, in different countries, mining and civil projects. The Q-slope allows engineers to adjust and optimize slope based on field observations of some geomechanical and geometric parameters that are easy to obtain. The selection of the value of each of the different parameters is made based on tables [2] some of whose parameters are the same as in the tunnel Q index, e.g. roughness (Jr), alteration (Ja), RQD etc. However, if the rock engineering has to analyse many slope with different properties, it is not so intuitive to work with very detailed tables and descriptions. We have therefore based ourselves on the concept of the graphic Geological Strengh Index [3] that uses short descriptions and designs. In this investigation we have selected the two parameters that form the pair of frictional resistance Jr / Ja (joint roughness number and joint alteration number. This Jr / Ja coefficient is very important since it is the multiplied by a correction factor for favorable or unfavorable orientation called O-factor. This O-factor is one of the novelties of the Q-slope compared to the “classic” Q of tunnels. Throughout the investigation we have simplified the descriptions of Jr and Ja (referring the reader to the previous works to know these parameters in grater detail) and created some graphic images that are easy and friendly to implement on site with a multiple choice table.
Comparison between methods for calculating the volume of rock blocks
Authors: Carriero M T , Ferrero A M , Migliazza M R , Umili G 
Published: September 2021

Abstract
Many methods for calculating the volume of rock blocks have been developed in the last decades. The first attempts to estimate such crucial quantity produced analytical equations to calculate the mean and variance of volume, considering blocks created by three discontinuity sets with a certain spacing probability distribution. From then, the research community followed three kinds of approaches for calculating block volume: the fully analytical one (e.g., Palmstrøm’s formula), the fully probabilistic one (e.g., Discrete Fracture Network generators), and the mixed one (e.g., In Situ Block Size Distribution). In this paper, a comparison among the different methods is presented, supported by numerical examples, highlighting their strengths and disadvantages in terms of reliability and repeatability.