bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toppling of a rock block resting on a rough surface
Authors: Alejano L R , Gui J Y , González-Fernández M A , Pérez-Rey I , Muñiz M 
Published: January 2023

Abstract
The main aim of this study is trying to contribute to a better understanding of the role of surface roughness basal planes on toppling-related instability phenomena. In this way, the authors focus on the stability against toppling of a single block resting on a regular rough surface. To do that they have first artificially created sample rock blocks with a regular rough base and tested them against toppling in a tilt-test machine. The authors have also developed analytical formulations to theoretically estimate toppling instability under these circumstances and have carried out simple numerical DEM models to reproduce the corresponding tests. The comparison between obtained analytical and numerical results and the physical model response indicated good representativeness of both numerical and analytical approaches. Geometry characteristics of the saw cut artificially created blocks did affect results, so the numerical and analytical models were adapted by including an equivalent curvature radius in the corner of the cut block around which the overturning phenomenon takes place to account for this geometrical effect. Further research will extend these results to the case of blocks with natural irregular rough surfaces.
Identifying the “unidentifiable” contributors to large-scale instability experienced at a UG2 mine along the Western Limb of the Bushveld Complex
Authors: Plessis M du , Liebenberg S 
Published: January 2023

Abstract
The geology intersected by a mining excavation dictate the rockmass condition and stability of the excavation. The general geologic structure of the UG2 Reef horizon with regard to rock type, jointing and potential parting planes are well understood. Mining layouts and support applications are applied to control the anticipated rockmass behaviour. Case studies conducted at several instability sites have, however, revealed that in most cases the rockmass behaviour is controlled by the geologic structure which may appear as intact joints visible from scanline or borehole core mapping. The significance of these structures within the hangingwall is mostly not visible in a 3-dimensional space. The prominent structure is related to deformation processes which crosscut the strata and ramp to areas with strength competent contrasts (i.e. stringers or alteration layers). As a result large-scale instabilities may occur. The extent of these structures are only realised following large-scale instability. At the study site a combination of visual observations, scanline and borehole mapping, ground penetrating radar and high definition 3-dimentional laser scans were used to interrogate the geologic structure intersected along the hangingwall of a stope contributing to the instability experienced. The intent was to identify the precursors of these “unidentifiable” structures present in the unexposed hangingwall. The paper discusses the findings of the investigation conducted.
Experimental study on fracture processes of granite cylinders with different decoupling conditions
Authors: Chi L Y , Zhang Z-X , Yang J , Qiao Y 
Published: January 2023

Abstract
Fracture processes of granite cylinders (a diameter of 240mm and a length of 300mm) subjected to blast loading were investigated using data from three-dimensional digital image correlation (DIC) method on images captured with two high-speed cameras. The five cylinders had a centric decoupled charge (PETN) of approximately 3 g or 4 g. The centric borehole with diameter 10mm or 20mm was drilled in each cylinder, and the charge diameter was around 6 mm/7 mm. Two decoupling ratios were applied, and each specimen has a decoupled charge with water or air. A partial cylindrical surface was captured by the high-speed cameras. Both the decoupling ratio and the filled-in medium influence the fracture pattern and initiation on the surface. The specimens with the air-decoupled charge produces gas ejection 440 μs-460 μs after detonation, while the specimen with the water-decoupled charge presents gas ejection at 960 μs. Displacement fields determined from the 3D DIC analysis were used to obtain strain fields on the observed surface. It is found that the initial strain on the surface was seen approximately 40 μs after the detonator initiation. The air-filled gap yields the vertical strain concentration zone in priority, while the water-filled gap produces horizontal concentration zone. The strain concentration corresponded well with the locations and direction of the developed cracks. The experimental findings of this investigation indicate that the decoupling ratio and decoupled materials have a great impact on rock fracturing.
A weakening-healing law to simulate stick-slip behavior of rock joint and the associated seismicity
Authors: Bai Qinsheng , Konietzky Heinz 
Published: January 2023

Abstract
The variation of frictional strength of asperities is one of the fundamental mechanisms that govern earthquake cycles. The rate - and - state friction (RSF) law has been widely employed to explain earthquake phenomena. In RSF, the frictional strength of fault depends upon the current slipping velocity and the conditions on the slipping surface (i.e., the state), which depends partly on the prior sliding history. In this study, we proposed a simplified weakening-healing law to describe the slip behavior of individual asperity. In the weakening-healing law, the friction strength linearly decreases to the residual value with shear displacement when slip occurs, and immediately recovers to its original value once slip terminates. In the numerical model, a power-law distribution is used to introduce asperity heterogeneity (e.g., size, frictional strength, and stiffness) on a rock joint. A displacement-based moment tensor method is used to calculate the seismic moment during fault slipping. The simulated b-value (magnitude-frequency distribution) and its evolution during stick-slip phases are compared with published experiments. Slip nucleation, growth, coalescence, and the associated spatial-temporal behavior of the simulated seismicity are delineated. Although this preliminary study focuses on simplified conditions (small-scale smooth rock joint sheared under constant normal pressure and shear rate), our method successfully duplicates laboratory observed stick-slip behavior, b-value evolution, slip nucleation process, etc., providing a promising way to mimic more realistic natural earthquake phenomena.
Validation of a Continuum-based Weak Zone Joint Model for Simulating Anisotropic Rock Mass Strength
Authors: Ziebarth R A , Corkum A G , Kinakin D , Stilwell I 
Published: January 2023

Abstract
In recent decades, the approach to estimating rock mass strength and its anisotropic behaviour more accurately has been a growing topic of interest in the rock mechanics community. To evaluate jointed rock mass behaviour more accurately, sophisticated modelling techniques such as Synthetic Rock Mass (SRM) models are becoming increasingly popular. Still, these methods are computationally intensive and require detailed site characterization data that are often unavailable during the initial stages of project development and are not always the most practical option. This study developed an alternative continuum-based SRM-like model where thin contiguous regions of weak continuum material with equivalent joint properties are in place of explicit interface joint elements. The finite-difference program FLAC used these weak zone joints (WZJ) to generate a jointed rock mass continuum model (JRCM). The JRCM concept was applied to systematic sets of persistent joints, a single non-persistent joint, and two intersecting joints to validate the practicality of using WZJ. Results found that the concept produced reasonable anisotropic rock mass strength estimates for most cases, with some limitations. The model captured the anisotropic behaviour while reducing time requirements to develop and recalibrate a conventional SRM. The JRCM concept demonstrates a practical alternative to estimating anisotropic rock mass strength for specific projects where the quantity or quality of data is limited. Furthermore, the reduced run times could allow multiple iterations to perform a probabilistic assessment of the rock mass strength.
A new experimental device developed to study the creeping behavior of a rock joint under shear stress
Authors: Jung Sophie , Ghabezloo Siavash , Bornert Michel , Pouya Amade , Lebihain Mathias , Archez Julien , Lemaire Marine , Chabot Baptiste , Vu Minh Ngoc 
Published: January 2023

Abstract
In the context of nuclear waste management project Cigeo, the behavior of the fractured Callovo Oxfordian claystone (COx) is studied for its time dependent effect on the long term convergences of the drifts. We present an experimental setup designed to investigate the viscous behavior of a fracture. While few experimental setup already exist with the purpose of studying the time dependent deformation of a rock joint, all of them measure the displacement in the direction of the sheared discontinuities in one point of the sample with devices such as a linear variable displacement transducers (lvdt). The information provided by this sensor comes to measuring the average displacement of the fracture slip. Depending on the configuration of the experimental device, the lvdt sometimes also measures the deformation of the rock medium which cannot always be considered as a rigid body. Which is why we propose in this paper to set a camera up in order to use Digital Image Correlation to get an information of the slip along the fracture.
Experimental investigation of the effect of thermal cycling on the thermomechanical properties of three rock varieties for high temperature thermal energy storage
Authors: Fränzer S , Jeskulke J , Neumann K M , Schumski S , Thomas S L , Duda M , Witte L C , Brajer C , Backers T 
Published: January 2023

Abstract
During the past years “rock batteries” have become increasingly relevant for the storage of renewable energy sources, such as wind and solar energy, because of their economic and ecological advantages with respect to previously more common materials for thermal energy storage (TES) such as salt. In rock-based TES systems, thermal energy is stored in packed-bed rock using air as heat transfer fluid. We investigated three different rock types with respect to changes in thermomechanical properties after different numbers of thermal cycles, Ruhr sandstone (Oberste quarry in Dortmund - Germany), basalt (commercial MTV basalt) and Calanca gneiss. Cylindrical samples were heated to 800°C within 11,5 h before temperature was kept constant for another 30 min and then decreased within 11,5 h. Samples were thermomechanically investigated before thermal treatment, and again after 1, 3, 7 and 15 cycles. Additionally, two samples of each rock type were subjected to a thermal cycle with a maximum temperature of 450°C and to 1000°C, respectively, at a heating/cooling rate corresponding to that of the samples heated to 800°C. Samples were characterised with respect to ultrasound wave velocity, bulk density, thermal conductivity, thermal diffusivity, uniaxial compressive strength, splitting tensile strength, mineral content (X-ray powder diffraction) and microstructure (thin section analysis). Samples of basalt could not withstand the standard heating rate. The samples crushed into small pieces also when heating rates were reduced and at a maximum heating temperature of 800°C. For sandstone and gneiss, the ultrasound wave velocity, bulk density, thermal conductivity, thermal diffusivity, uniaxial compressive strength and splitting tensile strength decreased systematically with increasing number of cycles, while the maximum reduction occurred after the first cycle and the relative reduction was similar between both rocks. Microstructural analysis indicated an increase in crack density and minor mineralogical changes upon heating. Both rocks, Ruhr sandstone and Calanca gneiss, appear suitable for TES, but Calanca gneiss is less suitable for temperatures above 800°C due to a significant reduction in bulk density and uniaxial compressive strength when heated to 1000°C. Also, its anisotropy and anisotropic response to heating can lead to preferred flow paths of the heat transfer fluid. Ruhr sandstone maintains a high uniaxial compressive strength of about 100 MPa even after 15 cycles while thermal capacity was only slightly reduced or even increased, and can be recommended for use in high temperature TES. This study is the outcome of a research-oriented teaching program at Ruhr-University Bochum within the Geoscience curriculum for students with focus on Engineering Geology. Student authors (Fränzer to Thomas) are listed in alphabetical order.
Data preparation for machine learning in rock engineering
Authors: Yang B , Nazari R , Elmo D , Stead D , Eberhardt E 
Published: January 2023

Abstract
Digitalization in rock engineering has resulted in significant technological advancements and the increasing use of machine learning techniques. As rock engineering transitions into becoming more data-driven, machine learning can help rock engineers improve the efficiency and utilization of large data sets in the design process. While machine learning is a powerful tool, the success of machine learning algorithms is intrinsically related to the quality and quantity of data available. It is commonly accepted that machine learning algorithms that are trained on poor quality data will result in poor and inaccurate (i.e. highly subjective) results. To limit the human factors that result from using data that represent qualitative assessments rather than objective measurements of physical properties, it is imperative to improve the data analysis and preparation/labelling process. Data preparation is especially important when applying machine learning to rock engineering problems due to the inductive and empirical nature of the design process as a result of the inherent variability of geological materials. Despite data preparation accounting for more than half of the machine learning process, there is limited research on data preparation for machine learning in rock engineering. This paper aims to fill this gap by providing a set of guidelines on the necessary data preparation steps for applying machine learning to rock engineering problems, thereby helping rock engineers improve the performance of their machine learning models.
Synergies between Heat- and Stress-Induced Spalling Theory Applied to Rock and Concrete in Tunnel Applications
Authors: Saha S , Serati M , Maluk C , Sahoo D R 
Published: January 2023

Abstract
Fire-induced and stress-driven catastrophic failures in rock and concrete are commonly known as spalling (or rockburst in its severe form) that have jeopardised the safety of personnel, seriously damaged rock structures, and shut down operations for months or even permanently in certain circumstances. Particularly in Australia, spalling and rockburst in deep excavations results in a heavy toll on mine safety and have become a constraint to the economic viability of several Australian deep mines since the early 1950s. The prevailing industry approach is to treat such unwanted failures and associated microseismic events as a result of insufficient energy absorption by the spalling-prone rock/concrete at the post-peak stage. However, this approach does not allow efficient handling of heat- or stress-induced failures as it requires an in-depth understanding of their mechanics. Prediction of these events based on the available failure criteria does not help either due to the numerous criteria involved and the difficulty in determining their parameters at the excavation scale. A proper understanding of the fracture growth in such failures is needed to understand the behaviour of rock or concrete structures resulting in a sudden release of energy at deep excavations. This paper investigates the similarities and differences between heat-induced concrete spalling and stress-driven rockburst and further examines the effect(s) of material, geometrical, geological properties, and the applied deviatoric stresses on these failure modes.
Some thoughts on rock slope stability issues in Mars
Authors: Aydan Ömer 
Published: January 2023

Abstract
In this study, the author outlines rock slope stability issues in Mars through the images provided by Mars Rovers of NASA and investigates the rock slope stability issues with the consideration of the various conditions such as layering, discontinuous nature of rock mass, overhanging, impact, vibrations as well as precarious rock blocks. Rock slope failures in Mars are categorized with references to those on Earth and the fundamental mechanisms are summarized. It is shown that. the methods developed for rock slopes can be utilized with due considerations of environmental and gravitational differences using the principles of Rock Mechanics. The outcomes of these investigations are presented and discussed in this contribution.
Probabilistic characterization of correlation between two rock properties: a data-driven approach
Authors: Aladejare A E , Akeju V O 
Published: January 2023

Abstract
Rock parameters are required during the design and stability analysis of mining and geotechnical structures. There is a correlation between some rock properties, especially those obtained from the same experimental set-up, and the proper estimation of such correlation is important for reliable mining engineering analysis. However, a limited quantity of rock property data often available for most mining project sites makes it difficult to estimate a reliable correlation between two rock properties. To overcome this challenge, a data-driven approach that is based on Bayesian framework is presented in this study. The approach utilizes limited data pairs of rock parameters from a site and characterizes the site-specific joint probability distribution of two correlated rock properties, without the use of an empirical model. Real data of rock properties obtained from uniaxial compression tests on migmatites at the Sanandaj-Sirjan zone in Iran is used to illustrate the approach. The results from the approach show that the marginal statistics, marginal and joint probability distributions, and correlation coefficient from the proposed approach are consistent with those of the measured data from the adopted site. This indicates that the approach is effective for characterizing the correlation between correlated rock properties and can be used when there is a need for such characterization at a site with limited data.
Application of DInSAR for monitoring slopes around a dam basin in Japan
Authors: Shoji Y. , Shigeoka Y. , Kikuchi T. , Shimizu N. 
Published: January 2023

Abstract
Monitoring the behavior of slopes around the sites of hydroelectric power plants and dam reservoirs is important from the viewpoints of their stable operation and a reduction in the risk to the local community. Since their facilities are widely located at dam sites, however, it is not easy to efficiently monitor the behavior of them. SAR can be a solution to the problem. On the other hand, there are still difficulties that must be overcome when applying DInSAR as an engineering tool for monitoring in practice, i.e., phase decorrelation, the accuracy and reliability of the results, etc. In particular, the dense vegetation that often covers mountainous areas can prevent the acquisition of precise measurement results. In this paper, DInSAR using ALOS-2 data is applied around a dam basin and the results are compared with the actual ground behavior to confirm the applicability of DInSAR. It is concluded that DInSAR using ALOS-2 data could be a useful tool for monitoring the slope stability of large dam basins, even those covered with dense vegetation.
Monitoring Fracture Saturation using Transportable Acoustic Sources and a Neural Network Differential Autoencoder
Authors: Nolte David D. , Pyrak-Nolte Laura J. 
Published: January 2023

Abstract
Acoustic signals from transportable acoustic sources were analysed using a Siamese twin neural network differential autoencoder (TDAE) to monitor changing fracture saturation within a laboratory testbed consisting of synthetic fractures. The small transportable acoustic sources, called “chattering dust” and introduced inside the fractures, generate hundreds to thousands of acoustic wavepackets that propagate across other fractures in the system. A 4-class study was performed using the TDAE by physically cycling among four different saturation conditions of the fractures. Accurate classification of all four fracture saturation conditions was achieved using mode-pooling. This work demonstrates that the twin neural network differential autoencoder, which is ideally suited to identify subtle differences among classes, can extract information about the conditions of fractures from complex and variable wavefields consisting of overlapping coda wave signals.
Micromechanical characterisation of overburden shales in the Horn River Basin through nanoindentation
Authors: Charlton T S , Rouainia M , Aplin A C , Fisher Q J , Bowen L 
Published: January 2023

Abstract
The paper presents a micromechanical characterisation of Fort Simpson shale, which overlies unconventional gas-producing lithologies in the Horn River Basin, NW Canada. The Fort Simpson formation is clay-rich and microseismic data recorded during hydraulic fracturing events in the underlying reservoir has shown the formation acts as a barrier to fracture development, with a notably anisotropic seismic response. Samples were prepared from core fragments and the composition and texture of the shale was characterised using X-ray diffraction, mercury injection porosimetry and scanning electron microscopy (SEM). Nanoindentation testing was used to obtain the mechanical response of the shale microstructure, at grain-scale. The indentation was conducted on a grid pattern and samples were oriented both parallel and perpendicular to the bedding plane to assess the inherent mechanical anisotropy. Chemical analysis of the grids was also undertaken through SEM/EDS (energy dispersive X-ray spectroscopy) and the coupled chemo-mechanical data was used to characterise the material phases of the shale through a statistical clustering procedure. The results show that Fort Simpson shale broadly consists of a soft clay phase, with strongly anisotropic elastic stiffness, and stiffer but effectively isotropic grains of quartz and feldspar. A simple upscaling scheme was also applied to link the grain-scale elastic stiffness to the field-scale microseismic data.
A Multimodel Bayesian Reliability Analysis for a Rock Slope to Counter Data Insufficiency
Authors: Kumar A , Tiwari G 
Published: January 2023

Abstract
Data insufficiency of input rock properties is a major issue to analyze the stability of slopes via traditional deterministic and reliability approaches. This data insufficiency in the properties arises due to complexities associated with in-situ and lab testing of rocks. The traditional Bayesian approach overcomes this issue by considering uncertainties in model parameters by combining available prior information neglecting the uncertainty associated with the distribution type/probability model. This study proposes a novel Bayesian multimodel inference approach to incorporate the uncertainties associated with probability models/distribution types along with model parameters for rock properties. The approach first identifies a set of candidate probability models and then employs the Bayesian framework to incorporate the parameter uncertainties for each model. The approach is demonstrated for a rock slope case with the potential of structurally controlled planar failure. It is concluded that the approach effectively treats the statistical uncertainties associated with probability model types and parameters with limited data and provides a more realistic stability assessment than the traditional Bayesian approach. Results show that the uncertainty in probability model parameters affects the stability of rock slope much more significantly than model types.