EMRP1.3 | Rock damage and progressive failure in geological and geo-engineering systems: theory, experiments and modeling
Rock damage and progressive failure in geological and geo-engineering systems: theory, experiments and modeling
Co-organized by GM6/NH3
Convener: Federico Agliardi | Co-conveners: Carolina GiorgettiECSECS, Amit Mushkin, Sergio Vinciguerra, Anne VoigtländerECSECS, Christian Zangerl
| Wed, 17 Apr, 14:00–15:45 (CEST)
Room -2.20
Posters on site
| Attendance Tue, 16 Apr, 16:15–18:00 (CEST) | Display Tue, 16 Apr, 14:00–18:00
Hall X2
Orals |
Wed, 14:00
Tue, 16:15
Rock mass deformation and failure at different stress levels (from the brittle regime to the brittle-ductile transition) are controlled by damage processes occurring on different spatial scales, from grain (µm) to geological formation (km) scale. These lead to a progressive increase of micro- and meso-crack intensity in the rock matrix and to the growth of inherited macro-fractures at rock mass scale. Coalescence of these fractures forms large-scale structures such as brittle fault zones, rockslide shear zones, and excavation damage zones (EDZ) in open pit mining and underground construction. Diffuse or localized rock damage have a primary influence on rock properties (strength, elastic moduli, hydraulic and electric properties) and on their evolution across multiple temporal scales spanning from geological time to highly dynamic phenomena as earthquakes, volcanic eruptions, slopes and man-made rock structures. In subcritical stress conditions, damage accumulation results in brittle creep processes key to the long-term evolution of geophysical, geomorphological and geo-engineering systems.
Damage and progressive failure processes must be considered to understand the time-dependent hydro-mechanical behaviour of fault damage zones and principal slip zones, and their interplay (e.g. earthquakes vs aseismic creep), volcanic systems and slopes (e.g. slow rock slope deformation vs catastrophic rock slides), as well as the response of rock masses to stress perturbations induced by artificial excavations (tunnels, mines) and loading. At the same time, damage processes control the brittle behaviour of the upper crust and are strongly influenced by intrinsic rock properties (strength, fabric, porosity, anisotropy), geological structures and their inherited damage, as well as by the evolving pressure-temperature with increasing depth and by fluid pressure, transport properties and chemistry.
In this session we will bring together researchers from different communities interested in a better understanding of rock deformation and failure processes and consequence, as well as other related rock mechanics topics. We welcome innovative and novel contributions on experimental studies (both in the laboratory and in situ), continuum / micromechanical analytical and numerical modelling, and applications to fault zones, reservoirs, slope instability and landscape evolution, and engineering applications.

Orals: Wed, 17 Apr | Room -2.20

Chairpersons: Federico Agliardi, Amit Mushkin, Carolina Giorgetti
Laboratory studies
On-site presentation
Ian Main, Maria-Daphne Mangriotis, Alexis Cartwright-Taylor, Andrew Curtis, Ian Butler, Andrew Bell, and Florian Fusseis

Catastrophic failure is the end result of a progression of damage towards brittle failure on a variety of system scales in the Earth. However, the factors controlling this evolution, and the relationship between deformation and the resulting earthquake hazard, are not well constrained.  In particular, induced seismicity is a growing cause of concern in the engineering required for the net-zero carbon transition, including subsurface storage of carbon and geothermal energy production, and mining for critical metals. Here we address the question of how to optimize operational controls to minimize induced micro-seismicity in a ‘scale-model’ laboratory experiment where we can simultaneously image the underlying damage using acoustic emissions (sound) and x-rays (vision). We confirm that using continuous servo-control to maintain a constant acoustic emission event rate slows down deformation compared to standard constant strain rate loading, and demonstrate that it also suppresses micro-seismic events of all sizes, including extreme events, and reduces the proportion of seismic to total strain. We develop a new model to explain these observations, based on the observed evolution of microstructural damage and the fracture mechanics of subcritical crack growth.  The model is validated with high precision (r~99%) by comparison with the independently-observed stress history and acoustic emission statistics.

Qualitative inspection of comparable grey-scale x-ray volumes between the two experiments (peak stress and post-failure after unloading) showed that at peak stress microcrack damage accumulated initially, in both samples and in the same area of each sample, as localised pore collapse, pore-emanating and Hertzian tensile intra- and trans-granular cracks and pore-emanating shear and tensile inter-granular cracks. These features were mostly similar in length and aperture, although the sample loaded only under constant strain rate showed a few longer and more open cracks. Strain localisation was apparent at the same stage in both samples, but there was some evidence of earlier en-echelon microcrack localisation in the sample loaded under a constant strain rate. Post-failure, microcracks were longer and more open in the sample loaded under a constant strain rate than in the sample loaded under a constant AE event rate. The visible proportion of damaged rock was greater, with a broader shear zone around two to three grains wide (compared with <1-2 grains) and a greater degree of cataclasis throughout. Off-fault microcracking was limited, but there were some trans- and inter-granular microcracks that extended up to four to five grains long in both samples. These were more common in the sample loaded under constant strain rate and tended to be more open. Finally, branching of the fault zone appeared to be more pronounced in the sample loaded under a constant strain rate.

Our results explain the effectiveness of seismic event rate control on seismic hazard mitigation in mining settings, and imply that it may be more effective in managing the risk from induced seismicity in a pre-emptive way than the commonly-applied ‘traffic light’ system, which is based on reacting after the fact to extreme events.

How to cite: Main, I., Mangriotis, M.-D., Cartwright-Taylor, A., Curtis, A., Butler, I., Bell, A., and Fusseis, F.: Progressive rock failure under different loading conditions – sound and vision, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5553, https://doi.org/10.5194/egusphere-egu24-5553, 2024.

On-site presentation
Seiji Nakagawa, Yida Zhang, Hooman Dadras, Zhao Hao, Anne Voigtländer, and Benjamin Gilbert

Subcritical crack growth accelerates weathering of rocks and minerals, reduces the strength of rock slope, and affects the stability of subsurface faults. Under special circumstances, the produced cracks can also heal spontaneously (Self healing) regaining a part of the original tensile strength.  These crack behaviors are a manifestation of molecular-scale surface forces acting between the surfaces near the crack tip. As a part of the effort to understand how these forces control the subcritical crack growth and healing of geological materials, we examine the tensile crack behavior of calcite single crystals. A miniature Double-Torsion (DT) test system was developed for testing small plate samples (40 mm x 20 mm x 1.5 mm) cut out of optical-quality calcite single crystals (Iceland Spar crystals). These samples are oriented in such a way that the induced crack is along the (1014) plane (the primary cleavage plane). The main output of the experiment is the crack velocity (vc) vs the magnitude of applied driving force (stress intensity factor K or strain energy release rate G), which is a typical way to summarize the rate-dependent crack behavior. From the experiment, we have learned that (1) calcite exhibits strong healing behavior compared to materials such as glass or (amorphous) quartz in humid air and water, (2) healing is time dependent (the strength of a healed crack increases over time), (3) liquid water (rather than vapor) introduces strong hysteresis in the recracking vs healing behavior.   The obtained laboratory data are used to develop a mechanistic model for predicting macroscale crack behavior in rock, particularly in a water and electrolyte-rich environment.

How to cite: Nakagawa, S., Zhang, Y., Dadras, H., Hao, Z., Voigtländer, A., and Gilbert, B.: Laboratory measurement of subcritical crack growth and healing in calcite using Double-Torsion tests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13669, https://doi.org/10.5194/egusphere-egu24-13669, 2024.

On-site presentation
Erina Prastyani, Benoît Cordonnier, Jessica McBeck, Lei Wang, Erik Rybacki, Georg Dresen, and François Renard

Rocks exhibit a brittle failure mode, leading to system-size failure through cataclastic faulting processes involving microfracture coalescence and frictional sliding, resulting in localized deformation. In contrast, the ductile failure mode can be described as a distributed deformation at the macroscopic scale, although there may be significant grain-scale heterogeneities. The transition between these two modes is an important research area because it is assumed to occur at the base of the seismogenic zone where large earthquakes may nucleate. Understanding strain evolution and partitioning between brittle and ductile failure modes may shed light on the preparation process for large earthquakes. To investigate the transition from brittle to ductile deformation, we performed two series of experiments on Carrara marble core samples: conventional triaxial experiments with acoustic emission recording at GFZ Potsdam, and dynamic in situ 4D X-ray imaging experiments on beamline BM18 at the European Synchrotron Radiation Facility.  Carrara marble is used as a rock model because this transition can be achieved at room temperature. We performed the experiments at room temperature and confining pressures between 5 and 100 MPa. For the synchrotron experiments, we segmented the images and implemented digital volume correlation (DVC) analyses between tomogram acquisitions to quantify the evolution of volumetric and shear strain components during the transition from the brittle to ductile regime. The results show that the transition is controlled by the dynamics of microfractures, even in the ductile regime. Below 40 MPa of confining pressure, deformation localizes along faults, particularly at 5 and 10 MPa. At 40 MPa, tomograms reveal the formation of a localized shear zone and macroscopically distributed deformation, resembling a semi-brittle regime. The DVC reveals the spatial extent of the strain directed into faults. A limited number of acoustic emissions recorded at this confining pressure revealed the prevalence of aseismic activity during deformation. Above 40 MPa, deformation shifts to a non-localized pattern at the core sample scale, involving the opening of microfractures, possibly due to the cataclastic flow mechanism accommodating this regime.

How to cite: Prastyani, E., Cordonnier, B., McBeck, J., Wang, L., Rybacki, E., Dresen, G., and Renard, F.: Revealing the transition from brittle to ductile failure mode in Carrara marble through in-situ 4D X-ray imaging and acoustic emissions experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8848, https://doi.org/10.5194/egusphere-egu24-8848, 2024.

On-site presentation
Manuel Asnar, Christoph Sens-Schönfelder, Audrey Bonnelye, Georg Dresen, and Marco Bohnhoff

In rocks and other consolidated geomaterials, static or dynamic excitation leads to a fast softening of the material, followed by a slower healing process in which the material recovers all or part of its initial stiffness as a logarithmic function of time. This requires us to exit the framework of time-independent elastic properties, linear or not, and investigate non-classical, non-linear elastic behavior and its time dependency. Softening and healing phenomena can be observed during seismic events in affected infrastructure as well as in the subsurface. Since the transient material changes are not restricted to elastic parameters but also affect hydraulic and electric parameters as well as material strength – documented for instance by long lasting changes in landslide rates – it is of major interest to characterize the softening and recovery phases.

To characterize this behavior in a controlled environment, we perform experiments on Bentheim sandstone in a Materials Testing System triaxial cell with pore pressure and confining pressure control. Our sample is subjected to various static loading cycles in both dry and water-saturated conditions, while an active acoustic measurement setup allows us to monitor minute P-wave velocity changes, which can then be directly tied to dynamic elastic modulus changes.

Our transducer array allows us to observe the dynamic softening as well as the recovery processes in the sample during repeated loading phases of various time lengths. Observations indicate high spatial, frequency and lapse-time sensitivity of the observed velocity changes, indicating a rich landscape of concurrent effects and physical phenomena affecting our sample during these simple experiments.

To investigate the spatial and directional dependency of the velocity changes, we restrict the analysis to direct and reflected ballistic waves. Our observations indicate that, while stress-induced classical effects are clearly anisotropic as expected, the non-classical effects do not exhibit significant anisotropy. This allows us to rule out a number of physical phenomena as the cause for the non-classical effects. Most importantly, we conclude that the microscopic structures responsible for the reversible softening and healing processes are different from the cracks that induce the anisotropic acousto-elastic effect.

How to cite: Asnar, M., Sens-Schönfelder, C., Bonnelye, A., Dresen, G., and Bohnhoff, M.: Non-linear softening and relaxation in rocks and geomaterials: a laboratory perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10753, https://doi.org/10.5194/egusphere-egu24-10753, 2024.

On-site presentation
Romane Le Dizes Castell, Rosa Sinaasappel, Clémence Fontaine, Scott Smith, Paul Kolpakov, Daniel Bonn, and Noushine Shahidzadeh

Frost damage in porous materials is a weathering mechanism that can cause dangerous rockfalls or damage to built cultural heritage. The volume expansion of 9% when water freezes can be one of the cause of frost damage. This does not, however, explain why partially saturated porous stones also show damage despite the fact that ice should have room to grow. By performing experiments both at the scale of a single pore and in a real stone, we investigate the mechanism of frost damage at low water saturations at the pore scale and how it relates to macroscopic damage. We observe that the meniscus at an air-water interface confines the water in the pores. Because of this confinement, ice that forms will exert a pressure on the pore walls rather than growing into the pore. The amplitude of stress is found to be larger in small pores and when the meniscus has a larger contact angle with the walls. The contact angle is also observed to increase in the case of multiple freeze-thaw cycles, which increases the likelihood of damage. We find that cracks start first in the ice (being weaker than the confining material), followed by damage in the material itself. Remarkably, when multiple air-water interfaces are induced within limestone samples through a hydrophobic surface treatment, the stones are much more susceptible to frost damage than are uncoated stones, with cracks appearing preferentially at the hydrophilic-hydrophobic interface. This shows that indeed the meniscus confining the water during freezing and consequently the wetting properties are the relevant factors for frost damage in partially saturated porous stones

Reference: R. Le Dizès Castell, R. Sinaasappel, C. Fontaine, S. H. Smith, P. Kolpakov, D. Bonn, and N. Shahidzadeh, “Frost Damage in Unsaturated
Porous Media,” Physical Review Applied, vol. 20, p. 034025, Sept. 2023.

How to cite: Le Dizes Castell, R., Sinaasappel, R., Fontaine, C., Smith, S., Kolpakov, P., Bonn, D., and Shahidzadeh, N.: Frost damage in unsaturated porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11304, https://doi.org/10.5194/egusphere-egu24-11304, 2024.

In situ / modelling studies
On-site presentation
Martha-Cary Eppes, Christian David, Mike Heap, Patrick Baud, Thomas Bonami, Maxwell Dahlquist, Russell Keanini, Cyril Lacroix, Monica Rasmussen, Alex Rinehart, Youness El Alaoui, and Adrien Windenberger

Rock physics theory and experimental data suggest that fracture growth in rock proceeds not only as a function of synchronous stress and environmental conditions but also as a function of past fracture growth in response to those conditions. ‘Stress memory’ or ‘fatigue-limit’ fracture mechanics phenomena such as the Kaiser effect epitomize this idea. Many questions exist, however, as to if and how these phenomena impact the growth of fractures under natural environmental conditions. For example, to what extent does the orientation of past experienced stresses manifest in a rock’s response to stresses of the same magnitude?

Here we test for a memory of intergranular thermal stresses in two natural granite boulders of the same lithology for which we have 1 and 3 years of known temperature history, respectively. We hypothesize that cores extracted from the exterior portions of the boulders – that have necessarily experienced more and larger temperature fluctuations – will have more ‘memory’ of peak temperatures than those cores extracted from the boulder centers. In turn, we hypothesize that outer cores will crack less in response to temperature cycling than inner cores. For the first boulder, we measured P-wave velocities and connected porosities before and after 4 different oven heat treatments – heating up to 40, 45, 50 and 65 °C at a rate of at 20 °C/hr and cooling at an ambient rate over several cycles each. For two transects of cores extracted from the natural upward facing surface down, and the natural west-facing surface inward, we found that porosities increased after each subsequent heat treatment, but by larger amounts with distance away from the outer rock surface, as hypothesized. P-wave velocities, however, both increased and decreased with different heating cycles and positions. Therefore, for the second boulder, we extracted a top-down transect of 5 cores and, using a special-made rig, found that the samples exhibit significant P-wave velocity directional anisotropy. We subjected these cores to the same heat treatments as those of the first boulder, but this time orienting the samples identically in the oven with respect to their original positions in the boulder. Preliminary data show similar results as the first boulder, with the outermost core cracking the least (as interpreted from porosity changes) relative to the inner cores. Ongoing work will examine changes in P-wave velocity in different directions relative to measured anisotropy as a function of heat treatment cycles. This work has important implications for understanding if and how, with ongoing global warming, Earth’s rocks will respond to ‘new’ temperatures. 

How to cite: Eppes, M.-C., David, C., Heap, M., Baud, P., Bonami, T., Dahlquist, M., Keanini, R., Lacroix, C., Rasmussen, M., Rinehart, A., El Alaoui, Y., and Windenberger, A.: Temperature “Memory” and Natural Rock Fracture at Earth’s Surface, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9825, https://doi.org/10.5194/egusphere-egu24-9825, 2024.

On-site presentation
Russell Keanini and the US, Israel, UK, Japan, France Rock Fracture Collaboration

Macroscopic equilibrium statistical mechanics is first used to interpret and predict thermally driven microfracture in rock. Application of the theoretical framework to three heating and cooling experiments, performed on granite and reported between 1989 and 2017, provides strong evidence that the temperature-, pressure- and volume-dependent average microfracture population within a given rock volume can be treated as an equilibrium thermodynamic variable.  This observation, in turn, suggests that thermoelastic microfracture, in rock and similar granular solids, can be predicted and interpreted using standard, process- and history-independent equilibrium thermodynamics.  In order to place equilibrium rock fracture and healing in context, we then consider nonreversible, permanent, i.e., nonequilibrium fracture. Here, pictorial, physical, and quantitative analyses of several common, thermally driven rock fracture processes are presented, including: a) terrestrial thermal exfoliation of single grains from diurnally heated rock surfaces, b) non-terrestrial thermal exfoliation of thin, near surface rock layers, as recently observed, e.g., on Bennu, c) terrestrial and non-terrestrial thermally-driven through cracking, and d) initiation of c).  We show how the form of the continuum momentum and energy conservation equations for thermoelastic materials – here, rock- provides a powerful, intuitive framework for quickly visualizing and roughly predicting the fracture/weathering processes in a) through d).

How to cite: Keanini, R. and the US, Israel, UK, Japan, France Rock Fracture Collaboration: Equilibrium (reversible) and nonequilibrium (permanent) fracture in rock: equilibrium statistical mechanics theory and experiments, and physical/intuitive analysis of common nonequilibrium fracture modes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7023, https://doi.org/10.5194/egusphere-egu24-7023, 2024.

On-site presentation
Aislin Reynolds, Karl Lang, and Chloé Arson

The formation of granitic domes via exfoliation jointing produces some of the most celebrated and hazardous landforms on Earth. In 1904, G.K. Gilbert outlined three mechanisms to explain exfoliation jointing as: (1) related to the original cooling of the rock body, (2) related to decompression of the rock body as it is exhumed to the surface of the Earth, or (3) related to processes at Earth’s surface - a hypothesis recently supported by observations of thermal cycling in crack initiation and propagation. Despite more than a century of study, our understanding of the mechanisms driving exfoliation jointing remains incomplete. This research seeks to address the question: is the formation of exfoliation joints more sensitive to surface processes (e.g., biotite weathering, thermal cycling), topographic, or regional (i.e. tectonic) stresses? To test this hypothesis, we predicted the orientation of fractures subject to variable geologic conditions with a multi-scale weathering model of damage and fracture propagation implemented in the finite element method. We present predictions resulting from thermal contraction during cooling of the rock body, depressurization during rock exhumation, and regional tectonic compression. We then compare fractures generated under variable topographic stresses, surface weathering processes, and rock geochemistry (i.e., biotite fraction and orientation). By improving our understanding of how significantly pre-existing geologic conditions and rock fabrics influence fracturing, we can work towards disentangling this effect on observed fracture orientations and better interpret paleo-stresses for major tectonic events or potentially paleo-topography. Additionally, enhancing models for weathering mechanics and fracturing in granitic bodies may reveal sensitivities to changes in climate and critical zone evolution, with implications for the forecasting of rockfall hazards in relation to projected temperature and climatic changes.

How to cite: Reynolds, A., Lang, K., and Arson, C.: A comparison of exfoliation joint formation mechanisms: what is the role of surface processes?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1197, https://doi.org/10.5194/egusphere-egu24-1197, 2024.

On-site presentation
Nathalie Casas, Guilhem Mollon, and Marco Maria Scuderi

Mature fault zones are formed by abrasive wear products, such as gouge, which results from the frictional sliding occurring in successive slip events. Shear localization in fault gouge is strongly dependent on, among others, fault mineralogical composition and grain size distribution, originating a wide variety of microstructural textures that may be related to different types of fault motion from aseismic creep, slow earthquakes to fast slip events. Within a quartz fault zone, one can encounter different stages of maturity, ranging from an incipient and poorly developed fault zone (i.e. discontinuous and thin gouge layer) to a mature fault zone that has experienced a lot of wear from previous sliding events (i.e. well-developed gouge layer). The localization of deformation within a mature gouge layer has been identified as possibly responsible for mechanical weakening and as an indicator of a change in stability within the fault.

However, to upscale the physics of shear deformation, we need to unveil the physical parameters and micro-mechanisms that govern shear localization. To gain insights on the role of dynamic changes in grain size (i.e. fragmentation), in slip behavior and fault rheology, we performed 2D numerical simulations of quartz fault gouges in a direct shear configuration using the Discrete Element Method (code MELODY). We can reproduce angular particles that can fragment during the simulation as the fault gouge accumulates strain. These experiments were performed to understand the micro-mechanical processes happening during fragmentation and shearing at a constant normal stress. Three mixtures of quartz were sheared to reproduce different initial grain size distributions within the fault (average grain sizes 100 μm, 10.5 μm, and a 50% mixture of both). The minimum grain size was set to 10 μm, meaning that all the coarser particles are subdivided into smaller ones (size 10 μm) that can fragment during the experiment.

Thanks to visual and data outputs, we can observe how particles behave during the compaction and shearing of the gouge. We use four main parameters to describe fault gouge evolution: the damage of coarse particles, the force chains, the change of porosity, and the kinetic energy linked to each particle breakage. Moreover, these numerical experiments were designed to reproduce and be directly compared with shear experiments realized on a double direct shear apparatus in the Laboratory (Casas et al., in prep). The fragmentation algorithm in the code can reproduce the shear localization observed within the real quartz microstructures and the progressive formation of Riedel bands. The connection between numerical and laboratory experiments gives important information on the connection between grain size distribution, shear localization, Acoustic Emissions, and the resulting fault slip behavior. In this context, the proportion between small/coarse particles within the fault plays an important role in controlling fault rheology.

How to cite: Casas, N., Mollon, G., and Scuderi, M. M.: The role of grain fragmentation in understanding shear localization via DEM simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9339, https://doi.org/10.5194/egusphere-egu24-9339, 2024.

On-site presentation
Elizabeth Petrie, Bradford Burton, Kelly Bradbury, and Genna Baldassarre

In south-central Idaho, a segment of the Pioneer fault, exposed at Little Fall Creek, has accommodated large magnitude Mesozoic shortening overprinted by Paleogene extension. The resulting 30 m thick fault damage zone records a history of fault reactivation and associated deformation in quartz veins, graphite concentration on slip surfaces, polyphase contractional and extensional microstructures, and micro- to outcrop-scale corrugated, mineralized and polished slip surfaces. The gently west dipping (207°/14°) fault zone separates Ordovician argillite in the hanging wall from Mississippian argillite and quartzite in the footwall and accommodated east-northeast directed shortening. However, polished slip surfaces within the fault zone document top-to-the-west translation with a mean slip vector 15°/272°, consistent with extensional unroofing of the Pioneer Mountains core complex.

Argillite in the fault damage zone varies from proto- to ultra-cataclasite and provides evidence for overprinting of contractional fabrics by extensional fabrics. The fault damage zone is characterized by multiple anastomosing slip-surfaces which indicate a history of slip surface interactions, fault growth, and reactivation. Early deformation features include graphitic foliations and stylolites, SC foliations, and ptygmatic folds consistent with shortening. Quartz veins, mica fish, and slip surfaces coated with graphite, amorphous carbonaceous material, and amorphous quartz phases, overprint the early deformation features and are associated with west-directed extension. Hydrothermal quartz veins that show at least five phases of deformation indicate multiple strain episodes and high strain rates. Raman spectroscopy and scanning electron microscope textural analysis of the graphite in the fault damage zone show a loss of crystallinity toward the primary slip surface. We infer the late-stage meso- to micro-scale features record seismic slip and fluid-rock interactions in a gently dipping fault zone.

How to cite: Petrie, E., Burton, B., Bradbury, K., and Baldassarre, G.: Strain history of the Pioneer fault, Idaho, USA – progressive deformation and associated crystallographic alteration., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13927, https://doi.org/10.5194/egusphere-egu24-13927, 2024.


Posters on site: Tue, 16 Apr, 16:15–18:00 | Hall X2

Display time: Tue, 16 Apr 14:00–Tue, 16 Apr 18:00
Chairpersons: Anne Voigtländer, Christian Zangerl, Sergio Vinciguerra
Laboratory studies
Deterioration laws of weak interlayers on slopes during wetting-drying cycles
Da Zheng, Jiangfan Liu, and Hongke Zhou
David Healy

Quantifying the changes in elastic properties of rocks during deformation is an important task. Effective Medium Theory (EMT), as formulated by Sayers & Kachanov (1995) relates the crack fabric (or damage) to the elastic properties. EMT has been successfully applied in the forward sense to predict the evolution of elasticity and related acoustic velocities in response to prescribed changes in crack density; and in the inverse sense to recover crack densities from laboratory measurements of acoustic velocities.  However, EMT fails to predict an important observation from laboratory studies of rock deformation: cyclic loading under uniaxial and conventional triaxial loads of rock samples can produce significant increases in Poisson’s ratio. These increases correlate with increasing number of cycles and with increasing crack density. This phenomenon has been known since the work of Walsh (1965), Brace et al. (1966) and Zoback & Byerlee (1975). More recent work by Heap & Faulkner (2008) and Heap et al. (2009; 2010) has extended the findings across a range of different lithologies.

Published EMT equations predict Poisson’s ratios that stay constant or decrease with increasing crack density. Resolving this discrepancy is important because Poisson’s ratio may play a key role in producing stress rotations in the damage zones of faults, thereby making them ‘weak’ and prone to slip even when the normal stress is high e.g. the San Andreas Fault (Faulkner et al., 2006; Healy, 2008). Building on the work of David et al. (2012 & 2020) incorporating the effects of crack closure, sliding on cracks (Kachanov, 1992) and grain boundaries (Sayers, 2018) during loading, and delayed back-sliding during unloading, closed form micromechanical equations have been derived to describe increases of Poisson’s ratio with increasing number of cycles. Critically, increases in Poisson’s ratio are predicted even without including the effects of new cracks. Examples are shown comparing the predicted changes in Poisson’s ratio using the newly derived equations to data from uniaxial and triaxial laboratory tests on cracked rocks.

How to cite: Healy, D.: Increases in Poisson’s ratio due to cyclic deformation in cracked rock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3893, https://doi.org/10.5194/egusphere-egu24-3893, 2024.

Matthieu Lusseyran, Alexandre Dimanov, Audrey Bonnelye, Jérôme Fortin, and Alexandre Tanguy

Understanding the damage processes in clay-bearing rocks is a decisive factor in geological engineering, and for instance considering nuclear waste deep geological repositories. But, more generally they may also contribute to localized deformation, and thus the rupture of fault gauges in seismic zones. However, owing to their complex mineralogy, multiscale microstructures and anisotropy, the mechanisms of clay-rich rock damage and their chronology are not yet well understood..

Here we focus on the impact of micro-damage on ultrasonic wave propagation velocity, which is confronted with the corresponding full deformation fields calculated by digital image correlation (DIC). 

The aim is to associate the acoustic signature with the active deformation mechanisms identified by DIC. To this end, an integrated experimental approach is proposed to  characterize localization and to identify the related deformation micro-mechanisms  during uniaxial compression of natural clayey rock samples (Tournemire shales) with two simultaneous measurements: 1) the evolution of P-wave velocity within the sample by active acoustics, 2) the development of the 2D mechanical full field by digital image correlation.

Both experimental techniques are well known, but the innovation of our approach is to combine simultaneously both measurements. Deformation localization is a multiscale problem, which obviously occurs at the sample scale, but also at the fines scales of the microstructure. Therefore, we developed two different experimental setups. On the one hand, during uniaxial compression with a standard MTS loading frame the macro-scale localization patterns are characterized by optical observations, which image resolution is well suited to the cm sample scale (sample diameter: 3.6 cm and double in length). On the other hand, in order to characterize the initiation of micro-damage at the microstructure scale of the composite type of rock, the same loading protocol is reproduced (while keeping the acoustic diagnosis) on smaller scale mm-sized specimens (sample diameter : 8 mm, double in length), using a home-designed miniature loading frame fit for an environmental scanning electron microscope (ESEM). The latter analysis is carried out under  controlled relative humidity  of RH = 80%, hence preventing the samples to dry out due to the high vacuum

A similar acoustic signature is identified at both scales of observation, in spite of the variations of experimental conditions imposed by the environmental SEM. We are therefore confident to be able to understand the fracturing process from micro-cracking initiation (microscale) to sample failure (macroscale), and to assess its impact on ultrasonic wave propagation.

How to cite: Lusseyran, M., Dimanov, A., Bonnelye, A., Fortin, J., and Tanguy, A.: Multi-scale experimental deformation and damage initiation of clay-rich rocks  : Coupling ultrasonic wave propagation and  full field deformation measurements by digital image correlation (DIC), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9811, https://doi.org/10.5194/egusphere-egu24-9811, 2024.

Xinjie Li, Alexandre Dimanov, Michel Bornert, Simon Hallais, and Hakim Gharbi

In the context of the global environmental crisis and the urgent need for energy transition and efficient energy storage solutions, salt caverns have gained attention as promising reservoirs for hydrogen. However, current literature predominantly focuses on deriving macroscopic constitutive relations, lacking crucial insights into the underlying physical mechanisms of deformation and damage active at various microscopic scales. This study addresses this gap by undertaking qualitative and quantitative investigations into the micro-mechanisms of rock salt, employing advanced micro-scale observation techniques. Natural rock salt from diverse mines and re-synthetic salts, produced through the cold compaction of grinded natural halite powder, are used to encompass a wide range of microstructural morphologies. Initial microstructure characterization involves SEM, EBSD, and CT, followed by classic uniaxial compressive tests coupled to optical microscopy monitoring. High-resolution images of the sample surface are continuously captured during testing, allowing for 2D full field measurements by subsequent application of digital image correlation techniques : the analysis of relative displacements of markers randomly distributed on the sample surface enables the retrieval of surface displacement fields and the calculation of the corresponding local strain fields over statistically representative domains. Segmentation of digital images and quantitative identification, specifically focusing on crystal slip plasticity and grain boundary sliding using an in-house computation program, reveal the complex local interactions of different micro-mechanisms. The estimation of the relative contributions of these mechanisms to global deformation all along the loading path, along with an analysis of the impact of salt grain size, provides insights into physically grounded micromechanical constitutive relations. These findings are essential for the safety assessment of industrial applications involving rock salt caverns with respect to short-term mechanical loading conditions relevant to daily hydrogen filling and withdrawal.

How to cite: Li, X., Dimanov, A., Bornert, M., Hallais, S., and Gharbi, H.: Multiscale experimental investigation of crystal plasticity and grain boundary sliding in rock salt using digital image correlation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10099, https://doi.org/10.5194/egusphere-egu24-10099, 2024.

Hao Chen, Paul Selvadurai, Antonio Salazar, Patrick Bianchi, Sofia Michail, Markus Rast, Claudio Madonna, and Stefan Wiemer

Recent observations of large earthquakes document the progressive localization of rock damage around future rupture zones that is also coupled with the spatial migration of foreshock sequences (Kato & Ben-Zion, 2020). This implies that the precursory deformation may act as a potential tracer for preparatory process that result in large earthquakes. It has also been observed that self-organization of the localized damage regions can govern the eventual macroscopic brittle failure in geomaterials (Renard et al., 2019). How the presence of fluid controls the self-organized precursory deformation along localized damage zone remains an open question. In this study, we have performed two triaxial compression experiments on dry and water saturated Berea sandstone, using distributed strain sensing (DSS) technology to visualize the strain field on the sample surface (Salazar Vásquez et al., 2022) with high spatial resolution. By tracking components of the strain field, specifically the region on the sample that sustained the largest incremental change in strain, we tested the effect of fluid on the predictability of phase transition between intact and failed state, under the context of critical hypothesis. Strain was progressively localized around the eventual faulting region for both samples, while a slow faulting was observed in the wet sample accompanied by a diffuse deformation pattern and unstable crack nucleation at failure. The results showed that, the failure in the dry sample was preceded by a critical power law acceleration of the largest increment, thus the dynamic faulting occurred in a well-defined singularity. The strain distribution also provided evidence for a predictable evolution of precursors. In contrast, the wet test showed evidence for a first-order transition with an exponential increase in largest increment, leading to an abrupt failure with a transient increase of strain. We interpreted this abrupt transition to be due to the increasing dominance of fluid-driven subcritical crack growth in the faulting. In this process, the local stress at crack tips decreases with crack lengthening, hence impeding the crack interaction and leading to an abrupt development of fault network. Our observation unravels the mechanisms of precursory deformation with fluid-assisted subcritical cracking, which has important implication in forecasting large earthquakes in nature.



Kato, A., & Ben-Zion, Y. (2020). The generation of large earthquakes. Nature Reviews Earth & Environment, 2(1), 26–39. https://doi.org/10.1038/s43017-020-00108-w

Renard, F., McBeck, J., Kandula, N., Cordonnier, B., Meakin, P., & Ben-Zion, Y. (2019). Volumetric and shear processes in crystalline rock approaching faulting. Proceedings of the National Academy of Sciences, 116(33), 16234–16239. https://doi.org/10.1073/pnas.1902994116

Salazar Vásquez, A., Rabaiotti, C., Germanovich, L. N., & Puzrin, A. M. (2022). Distributed Fiber Optics Measurements of Rock Deformation and Failure in Triaxial Tests. Journal of Geophysical Research: Solid Earth, 127(8). https://doi.org/10.1029/2022JB023997

How to cite: Chen, H., Selvadurai, P., Salazar, A., Bianchi, P., Michail, S., Rast, M., Madonna, C., and Wiemer, S.: The influence of fluid pressure on the phase transition of brittle faulting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13010, https://doi.org/10.5194/egusphere-egu24-13010, 2024.

Sergio Vinciguerra, Thomas King, and Philip Benson

Parametric analysis of laboratory Acoustic Emission (AE) during rock deformation laboratory experiments has revealed periodic trends and precursory behaviour of the rupture source, as crack damage nucleates, it grows and coalesces into a fault zone. Due to the heterogeneity of rocks and the different effective pressures, finding a full prediction of rupture mechanisms is still an open goal.

4x10cm cylindrical samples of Alzo granite were triaxially deformed at confining pressures of 5-40 MPa, while AE are recorded by an array of twelve 1MHz Piezo-Electric Transducers. We trained a Time Delay Neural Networks (TDNN) on key seismic attributes derived from AE, such: Event rate, i.e. the negative log time difference between successive events; Amplitude, i.e. the average max amplitude of all waveforms for each single event AE; Source mechanism estimated from first-motion polarity spheres (King et al., JGR, 2021); Seismic scattering, i.e the ratio between high and low frequency peak delays (King et al., GJI, 2022); Vp/Vs ratios from vertical P-wave velocities and horizontal S-wave velocities for individual AE (King et al., GJI, 2023).

These timeseries are then classified by the TDNN as variations in stress and strain (target parameters). TDNN require continuous, regularly sampled data but AE are discrete and irregular. To transform the training data for the TDNN, parameters are smoothed in a weighted moving window of 100 AE events, where weighting is given towards high amplitude events that occur close in space together. Data processing is applied to waveform data from all experimental condition. Despite the inherent complexity in the raw data, clear increasing or decreasing trends are repeated at different experimental conditions.

Hyperparameters for the neural network are optimised using a Genetic Algorithm (GA) by evaluating the misfit between training target (mechanical data) and model output. Each model is trained on the 10 MPa dataset and validated on the 40 MPa dataset. Roles are reversed and the results summed. This approach ensures consistent trends in the training data (waveform parameters) whilst reducing bias towards a particular dataset. We then investigate 120 configurations for the training data following a ‘leave-one-out’ strategy. E.g., a model is trained on 5, 10 and 20 MPa datasets whilst omitting the Event rate parameter. The model is then validated on the 40 MPa dataset.

Model output on validation datasets demonstrate that the TDNN can classify AE-derived parameters as increasing variations in stress and strain. 10 and 40 MPa demonstrate the best fit and are likely linked to the GA optimisation, highlighting biases driven by the training data. Forecasting results for strain and stress reveal notable over- and under-estimations of values. However, both 10 and 40 MPa are generally accurate to within 20% further highlighting the feasibility of using a TDNN for forecasting the development of new fracture under conventional triaxial conditions.

How to cite: Vinciguerra, S., King, T., and Benson, P.: Using AE based Machine Learning Approaches to Forecast Rupture during Rock Deformation Laboratory Experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5440, https://doi.org/10.5194/egusphere-egu24-5440, 2024.

Field / modelling studies
Espen Torgersen, Karoline Arctander, Thomas F. Redfield, Anne Kathrine Svendby, Anna Maria Dichiarante, and Mari Lie Arntsen

Lineaments are elongated elements in spatial data such as valleys and ridges on topographic maps, or linear lows and highs in aeromagnetic data. Topographic linear depressions (topolineaments) are generally considered as the morphological expressions of easily erodable, elongated rock bodies situated within a mechanically stronger rock mass. In most circumstances topolineaments are even directly interpreted as faults and fractures, which forms the basis for lineament analysis study to understand brittle deformation patterns. However, topolineaments may also be formed by other tectonic and non-tectonic causes, such as alternating layers, foliation traces, dikes etc., or river- and glacial erosion not controlled by any bedrock features. This mix of potential causes begs the question: “How robust is actually lineament analysis for characterizing and quantifying faults and fractures?”. Testing the topolineament vs. fracture-relationship is not straight forward since topolineaments are usually occupied by rivers or creeks and covered with colluvium, which prevents direct observation of rock types and bedrock structures.

Underground excavations allow for continuous logging of bedrock types, rock mass quality and fracture density and orientations, which is done routinely at tunnel face during tunnel construction. Here we make use of such underground data from a large dataset of Norwegian road tunnels to compare the position of topolineaments spatially and statistically with rock fracture density and orientations in the subsurface. The tunnel dataset comprises data from across Norway in areas with widely varying bedrock geology, tectonic evolution, and geomorphology (e.g. etched surface, alpine, lowlands), which allow for an evaluation of the robustness of lineament analysis in various settings. Topolineaments are acquired using a newly developed algorithm (OttoDetect) run on both 10x10m and 50x50m resolution digital elevation models. The algorithm ensures that tunnel data is compared to a homogeneous and reproducible lineament dataset without operator or hillshade illumination biases.

Preliminary results from tunnels in areas with etched geomorphology show that c. 75% of all topolineaments correspond to weakness zones in the bedrock (i.e. very high fracture densities/very low rock mass quality compared to the surroundings). Hit rate increases for longer lineaments, which generally correspond to thicker fault zones. At the same time, only up to c. 60% of all weakness zones mapped at tunnel face can be spatially associated to a topolineaments, which demonstrate that significant brittle deformation is not expressed as topolineaments. Further analysis will be carried out to build a statistically robust dataset on the validity of lineament analysis.

How to cite: Torgersen, E., Arctander, K., Redfield, T. F., Svendby, A. K., Dichiarante, A. M., and Arntsen, M. L.: Are all lineaments the surface expression of faults and fractures? – A novel analysis using tunnel face mapping data from Norwegian road tunnels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16840, https://doi.org/10.5194/egusphere-egu24-16840, 2024.

Amit Mushkin, Ronen Boroda, Uri Malik, Nadav Lensky, Eyal Haggai, Boris Muravin, and Rivka Amit

Rock weathering is ubiquitously observed at or near Earth’s surface as a fundamental component in many landscape evolution process. In arid landscapes, where limited moisture availability restricts the rate and effectiveness of chemical and biological weathering – salt weathering (regarded herein as the physical disintegration of rocks in the presence of salts) is commonly acknowledged as an especially effective mechanism for progressive weathering of rocks. While volumetric expansion and contraction of salts in response to changes in ambient moisture conditions are broadly recognized as the primary drivers of salt weathering, our understanding of the environmental conditions that produce such moisture dynamics in otherwise extremely dry settings, such as hyper-arid deserts, remains largely unknown.

Here, we present preliminary results from field-based acoustic emission (AE) measurements for boulders with salt-laden cracks perched on abandoned shorelines of the hypersaline Dead Sea. Continuous measurements since April 2023 revealed daily fracturing activity displaying a bi-modal distribution with AE activity peaks during the early predawn and afternoon hours when T changes are minimal and RH fluctuations reach maximum or minimum values, respectively. Time-lapse photography revealed a recurring pattern of salts that crystalize along the rock cracks during the afternoon AE peak hours and subsequently disappear towards the predawn AE peak hours. The appearance of salt crystals during lowest RH conditions (warmest afternoon hours) and their disappearance during highest RH conditions (coldest predawn hours) suggests that stresses induced by repeated cycles of salt deliquescence/efflorescence in response to daily fluctuations in atmospheric RH are most likely responsible for the bi-modal distribution of daily fracturing activity. This suite of new field-based measurements of salt-weathering activity in natural hyper-arid settings suggests that atmospheric RH fluctuations and the volumetric changes they induce in hygroscopic salts can be key drivers of progressive rock fracturing in extremely dry and salt-rich environments on Earth and possibly Mars where other moisture sources are limited to effectively non-existent.

How to cite: Mushkin, A., Boroda, R., Malik, U., Lensky, N., Haggai, E., Muravin, B., and Amit, R.: Salt-driven Progressive Fracturing of Alluvial Boulders Along the Hyper-arid Shoreline of the Dead Sea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14362, https://doi.org/10.5194/egusphere-egu24-14362, 2024.

Progressive failure of rocks on asteroids and comets: review of recent studies and space mission’s results
(withdrawn after no-show)
Marco Delbo
Marco Dominguez-Bureos, Celine Hadziioannou, Ernst Niederleithinger, and Christoph Sens-Schönfelder

Time- and stress-dependency of elastic properties are features particularly observed in a variety of complex solids, ranging from steel, polymers, and cracked structures, to rocks and concrete. Recently, considerable effort has been made to understand the underlying physics of these phenomena commonly regarded as Nonlinear Mesoscopic Elasticity (NME) in laboratory setups.

As a result, various models have been suggested to explain a range of NME phenomena like hysteresis, dynamic softening, and slow dynamics, among others. Due to the high sensitivity of NME to the presence of imperfections or internal damage on solids, there is a growing interest in taking the current models and applying them to construction materials for damage assessment.

Intending to observe and incorporate these models into real-condition structures, we carried out a 1-day multifrequency vibration experiment in a 24-meter-long reinforced concrete test bridge equipped with a pretension system, to investigate the possible presence of internal damage with vibration-based methodologies.

We used the pretension system to subject the specimen to eight compression states in its longitudinal direction (forces of 400kN at the highest, and 280kN at the lowest). At every compression state, we struck the structure in the vertical direction three times on the north and south sides of the bridge with an impulse drop weight. Throughout the whole experiment, we recorded ambient seismic noise at different frequency bands with a 14-six-component sensor array to measure the acceleration in the conventional translational components and the angular velocity (rotation rate), a 14-geophone array of 4.5 Hz of natural frequency, and four pairs of embedded ultrasound transducers were used to estimate relative velocity changes (dv/v) by applying the Coda Wave Interferometry (CWI) stretching technique. internal temperature of the concrete was also recorded to correct our measurements by first-order thermal effects.

At the material scale (ultrasound regime) we observe stress-dependent dv/v at four different locations in the specimen and describe them by using the acoustoelastic effect concept regarded as a classical nonlinear phenomenon. We also analyze the relative velocity drop and the subsequent healing process in the concrete triggered by the action of the drop weight. We used the model of Snieder and Sens-Schönfelder (2017) to numerically describe the relaxation process happening at different time scales in the specimen through a deterministic inversion procedure. The north side of the structure showed to have a higher acoustoelastic effect and higher velocity drops, as well as longer relaxation times, it is important to mention that there is evidence of external cracking in this span of the bridge.

We present preliminary results in the seismic frequency band (structural scale), where we expect to observe the influence of the vertical beams that support the bridge on the spatial distribution of changes in dv/v. Changes in the fundamental frequency of the structure as a function of the stress level are also expected.

With this work, we point towards the development of new nondestructive testing methodologies highly sensitive to small cracks and imperfections using conventional and non-conventional seismic instruments, and linear and nonlinear wave propagation models.

How to cite: Dominguez-Bureos, M., Hadziioannou, C., Niederleithinger, E., and Sens-Schönfelder, C.: Time- and stress-dependent elastic properties in a concrete structure; spotting internal damage footprints, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16652, https://doi.org/10.5194/egusphere-egu24-16652, 2024.

Thermo-hydro-mechanical modelling of rock cliff-atmosphere interaction: the case of the Pozary test site in Czechia
(withdrawn after no-show)
Saeed Tourchi, Milad Jabbarzadeh, Hamed Sadeghi, and Arash Alimardani Lavasan
Reinhard Gerstner, Melina Frießenbichler, Michael Avian, Alexander Maschler, Christine Fey, Gerald Valentin, Markus Keuschnig, Volkmar Mair, Franz Goldschmidt, and Christian Zangerl

Deep-seated, high-alpine rock slides frequently occur in highly schistose, fractured, anisotropic rock masses. Many studies have shown that pre-existing geological structures are decisive for a rock slide’s initiation and kinematics, as they provide weakness zones that may be reactivated in the rock slide process. Besides this structural pre-disposition, internal deformation processes by brittle rock mass fracturing play an important role in the evolution of a rock slide. Nonetheless, the effect of multiscale rock mass fracturing due to the rock slide process is yet to be fully understood. Especially, as it is challenging to measure, characterize, and to numerically model these processes. In our contribution, we present three deep-seated rock slides located in the European Alps in heavily foliated, fractured rock masses with failure volumes above 500.000 m3 each. Focusing on these case studies, we investigate the internal deformation processes with a combined approach, comprising field mapping, laboratory testing, remote sensing, and numerical modelling.

During extensive geological field surveys, we mapped the geomorphological rock slide features and characterized the structural framework of each study site, yielding geometrical models of the rock slides. This provided the basis for our 2D distinct element modelling studies using UDEC, backed by lithological and rock mechanical laboratory investigations.

Whilst UDEC allows for modelling large displacement of blocks bounded by pre-existing discontinuities, it lacks the capability to simulate fracture initiation and propagation of new failure paths within intact blocks, thus neglecting brittle rock mass fracturing. We circumvent this constraint by tessellating the intact rock mass into random polygons – referred to as Voronoi elements. Here, we adapted the original Voronoi technique by assigning an asymmetry to the Voronoi elements, characterized by an elongated axis to consider rock mass anisotropy related to schistosity. By applying this approach, we modelled the fractured, anisotropic, metamorphic rock masses as a combination of pre-existing, field-related structures within a matrix of small, asymmetric Voronoi elements.

In order to confirm the model outputs, we used terrain and deformation data derived from various remote sensing techniques – e.g. satellite based synthetic aperture radar, terrestrial laser-scanning (Riegl VZ 4000) and several campaigns of unmanned aerial vehicle photogrammetry.

In our study, we were able to reproduce the failure mechanism and kinematics of all three rock slides in accordance with our remote sensing deformation data. Thereby, the asymmetric Voronoi tessellation proved to be feasible in reproducing the brittle rock mass fracturing processes in remarkable agreement with our observations in the field. Thus, our results show, how the formation and kinematics of deep-seated rock slides are controlled by the reactivation of pre-existing geological structures and brittle rock mass fracturing. In doing so, our integrated field, laboratory, and numerical modelling approach further contributes to a better understanding of rock slide initiation and kinematics in complex geological media.

How to cite: Gerstner, R., Frießenbichler, M., Avian, M., Maschler, A., Fey, C., Valentin, G., Keuschnig, M., Mair, V., Goldschmidt, F., and Zangerl, C.: High-alpine rock slides controlled by pre-existing geological structures and brittle rock mass fracturing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1670, https://doi.org/10.5194/egusphere-egu24-1670, 2024.

Pieride Mabe Fogang and Bingjie Huo

When excavating a tunnel, the stresses are distributed asymmetrically along the tunnel cross-section. Other factors, particularly slope friction force and excavation speed, can also contribute to the deformation and displacement of a tunnel. Despite this, several authors have used the complex potential method to predict the ground deformation surrounding the tunnel. However, their applicability to the ground response caused by the asymmetric stress distribution around the mine wall is analyzed in this context. This project, therefore, proposes an approximate solution on the slope to predict the mine cross-section deformation. The solution is based on the complex potential method to predict analytically and numerically the ground deformation around the tunnel. However, two variables called the “complex potential functions” for the Laurent series expansion are used for the stress redistribution to the tunnel boundary conditions. Data from the Datong mine case are used to justify the proposed analytical solutions. The solution is an essential guide for analyzing deformations in complex geological conditions and structures, such as steeper slopes.

How to cite: Mabe Fogang, P. and Huo, B.: Contribution of programming language to novel mine risk assessment project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3021, https://doi.org/10.5194/egusphere-egu24-3021, 2024.