ISRM 2023 - PUBLICATIONS

T09: Long term behaviour of underground structuresFrederico LARA (1), Lina-María GUAYACÁN-CARRILLO (1), Jean SULEM (1), Jana JABER (2), Jan CORNET (2), Gilles ARMAND (2)1: Laboratoire Navier/CERMES, Ecole des Ponts ParisTech, Université Gustave Eiffel, CNRS, Marne la Vallée, France; 2: ANDRA, Meuse/Haute-Marne Underground Research Laboratory, Bure, FranceInfluence of different support systems on drifts closure evolution in Callovo-Oxfordian claystoneAt the Meuse/Haute-Marne Underground Research Laboratory several research programs have been dedicated to: (1) knowledge improvement of the Callovo-Oxfordian claystone response to the excavation; (2) development of the different disposal systems. In order to increase the understanding of the rock mass formation and support interaction, a drift composed of different support systems has been monitored for several years. As this one is oriented along the minor horizontal principal stress, the measurements exhibit an anisotropic closure of the cross section with the vertical convergence being higher than the horizontal one. It is thus of interest to evaluate the effect of flexible support composed of compressible wedges and of the final concrete lining on the closure evolution. Also, extensometers measurements and the stresses on the temporary support are analyzed in different zones of the drift. Finally, the results are compared to those obtained from other drifts excavated in similar conditions. | Convergence measurements, Tunnel excavation, Tunnel lining, Deep geological repository, Callovo-Oxfordian claystone
T09: Long term behaviour of underground structuresMensan Dèlwindé Gildas Cedric AGBOLI, Dragan GRGIC, Albert GIRAUDUniversité de Lorraine, CNRS, Laboratoire GeoRessources, Nancy, FranceSelf-sealing experiments with water and gas injection on Callovo-Oxfordian claystone under X-ray tomographySelf-sealing tests with water injection were performed on artificially fractured core samples of the Callovo-Oxfordian claystone using an X-ray transparent triaxial cell. 3D X-ray scans and permeability measurements were performed continuously to assess the evolution of fracture volume and permeability. The impact of sample orientation (parallel and perpendicular to the bedding plane), calcite content and gas injection was analyzed. It resulted that the higher the calcite content, the less effective the self-sealing process. No significant influence of the sample orientation on the self-sealing process was identified. Self-sealing is generally fast at the beginning of the test and then stabilizes after one month. The initial permeability of the healthy claystone is partially restored, which is a promising result concerning the restoration of the initial sealing properties of the host rock. Injection of an inert gas has a delay effect on the self-sealing process due to the crack desaturation. | X-ray tomography, self-sealing, permeability, claystone, calcite content
T09: Long term behaviour of underground structuresRaphael SCHARF (1), Bernhard PICHLER (1), Roman HEISSENBERGER (2), Bernd MORITZ (2), Christian HELLMICH (1)1: Institute for Mechanics of Materials and Structures, TU Wien (Vienna University of Technology), Vienna, Austria; 2: ÖBB - Infrastruktur AG, Streckenmanagement und Anlagenentwicklung, Fachbereich Bautechnik - Tunnelbau, Graz, AustriaData and analytical mechanics: a new look on NATM tunnelsHybrid methods, i.e. combinations of deformation measurements with structural and material mechanics have been successfully used, for more than 20 years, for the New Austrian Tunneling Method (NATM), and beyond. This contribution extends these developments with respect to the mechanical behavior of such structures for more efficient evaluation of long-term behavior. In detail, internal shell-specific forces derived from the principle of virtual power are analytically linked, based on an aging viscoelastic material model, to radial and circumferential displacement components which were measured at selected points of the tunnel shell. For the Sieberg tunnel the data-driven analytical mechanics model evidences virtually uniform ground pressure distributions, leading to a ﬁrst rapidly increasing, and then mildly decreasing utilization degree of the shotcrete shell. | analytical mechanics, New Austrian Tunneling Method, aging viscoelasticity, shotcrete
T09: Long term behaviour of underground structuresMountaka SOULEY (1), Minh-Ngoc VU (2), Gilles ARMAND (2)1: National Institute for Industrial Environment and Risks (Ineris), France, France; 2: Radioactive Waste Management Agency (Andra), FranceLong term behaviour based on a weakness planes approach: Constitutive model and application to a Meuse/Haute-Marne (France) URL driftA constitutive model considering the natural and induced anisotropies in the short- and long-term behaviour is proposed by combining the elasto-visco-plasticity for rock matrix and weakness planes. The main assumption is that the failure of claystone material is due to the failure of the rock matrix and the fracturing along weakness planes. For intact matrix: (i) the short-term response includes the main mechanisms (transversely isotropic elastic, hardening, softening and residual plastic strain, brittle-ductile transition) evidenced in laboratory investigations, (ii) the long-term behaviour is based on Lemaître's model in agreement with the laboratory tests. The time-dependent response of weakness planes is described by the Maxwell’s model with a threshold. After checking the model on simple stress paths, its operational character is successfully demonstrated on the GCS drift (the more difficult to reproduce the overall observations). The computed convergences (and their ratio) and plastic zone extensions are consistent with the in-situ observations. | Constitutive model; Weakness planes, Plasticity, Time-dependent behaviour, M/H-M URL drift
T09: Long term behaviour of underground structuresJana JABER (1), Carlos PLUA (1), Minh-Ngoc VU (2), Gilles ARMAND (1), Jad ZGHONDI (1)1: Andra, Meuse/Haute-Marne Underground Research Laboratory, France; 2: Andra, Châtenay-Malabry, FranceEighteen years of feedback on the mechanical behavior of a 500m deep shaft on the Meuse/Haute-Marne (MHM) Andra’s URL (France)Clay formations in their natural state exhibit very favourable conditions for the repository of radioactive waste. In France, the Callovo-Oxfordian claystone has been studied by Andra as a possible host rock for radioactive waste disposal since the 1990’s. In 2004, Andra began the construction of an underground research laboratory (called the MHM URL) in Bure, starting with shaft sinking operations (to a depth of 500 m). One of the shaft lining and surrounding rock was instrumented. Its concrete lining is highly monitored to understand its long-term behavior and the evolution of the loading due to the surrounding rock mass. Instrumentations were installed at -455 m, -467 m, -479 m, and -504 m depth. This paper presents the data collected over 18 years of monitoring. The outcome feedback consolidates the robustness of the shafts design forecast for the French Industrial Centre for Geological Disposal (Cigéo project). | Shaft sinking, deep excavation, lining monitoring, Callovo-Oxfordian claystone, geological radioactive waste disposal, Underground Research Laboratory
T09: Long term behaviour of underground structuresTilman SANDNER, Claas MEIER, Boley CONRADBoley Geotechnik GmbH, GermanyRehabilitation of old masonry tunnels – challenges and possibilitiesThe Reicholzheim tunnel on the single-track line 4920 from Lauda to Wertheim had to be rehabilitated, since the existing tunnel lining, made of mortar sandstone blocks, is in a structurally poor condition. To rehabilitate the tunnel, the existing masonry shell was reinforced with a self-supporting reinforced concrete inner shell. The low clearance profile required partial removal of the masonry. Due to the vibration-sensitive structure and high rock strength, the milling work had to be carried out on the basis of a separate safety concept including high-pressure water cutting. To secure unstable areas of the vault, CFRP safety devices were installed. Due to the partly non-existent back-fill and the narrow time window during night-time closures, special requirements were placed on the concreting. As the responsible design-review-engineer, the design and compliance with the railroad regulations with regard to the innovative safety and rehabilitation measures were also challenging. | Tunnel rehabilitation, masonry shell, sandstone, CFRP safety devices, railroad regulations
T09: Long term behaviour of underground structuresKimihiro HASHIBA, Katsunori FUKUIThe University of Tokyo, Tokyo, JapanEffects of water on the time dependent properties of rockFor the long-term stability assessment of underground structures, it is essential to understand the effects of water on the time dependent properties of rock, such as loading-rate dependence, creep, and relaxation. In this study, the relation between the loading-rate dependence of strength and the stress dependence of creep lifetime in dry and wet conditions was examined on the basis of the previous experimental results of a tuff. It was found that the results of strength and short-term creep tests in dry and wet conditions are consistently explained with the rate process theory, which indicates that creep lifetime can be estimated from the loading-rate dependence of strength in a dry or wet condition. Using these theoretical and experimental findings, the creep lifetime in the ongoing 25-year creep test was predicted. | rock, strength, loading-rate dependence, creep, water
T09: Long term behaviour of underground structuresWen-Jie SHIU (1), Fu-Yuan HSIAO (1), Cheng-Hsien TSAI (1), Shih-Hui WANG (2)1: Sinotech, Taiwan; 2: Raito Engineering Corp., TaiwanCreep induced tunnel collapse during construction – a case study of a mountain railway tunnel in TaiwanThe mountain railway No. 42 Tunnel once collapsed during construction when only the primary shotcrete lining was in place. According to geological analysis and excavation records, the major cause of disaster was presumably due to time-dependent behavior of rock. In order to elucidate the impact of creep-induced displacement during excavation, a simulation-based methodology, i.e. a viscoplastic model combining the two-component power model and the ubiquitous-joint model, is proposed. The time dependent parameters were calibrated using the back analysis from the convergence measurement data. The modelling results have illustrated that the excavation induced displacement can be dissociated into two parts, the instantaneous deformation due to stress relaxation, and the time dependent deformation due to creep. The overall study in terms of current findings has shown that our proposed model is a useful tool for investigating long term stability of tunnels surrounded by creep potential rock material. | viscoplastic model, creep behavior, convergence, tunnel excavation
T09: Long term behaviour of underground structuresKwang-Il KIM, Changsoo LEE, Dong-Keun CHOKorea Atomic Energy Research Insitute, Republic of Korea (South Korea)Coupled thermo-hydraulic-mechanical analysis for a high efficiency high-level radioactive waste repository in South KoreaThis study analyzes enhancement of disposal efficiency inversely proportional to disposal area based on three design factors for the high-level radioactive waste (HLW) repository such as decay heat optimization, increased thermal limit of buffer, and double-layer concept. If the repository is designed with the optimized decay heat model, the disposal efficiency increases to 2.3 times of the improved Korean Reference disposal System (KRS+). Additional to the decay heat optimization, increasing thermal limit of buffer to 130 °C or using the double-layer concept provides extra 50 % improvement of the disposal efficiency. If the three design factors are applied all together, disposal efficiency can be enhanced to the five times of the KRS+ repository. Rock mass stability analysis indicates that failure of rock is focused at the corner between the disposal tunnel and deposition hole, and rock spalling failure is generated in the wider area if the thermal limit of buffer is increased. | Coupled thermo-hydraulic-mechanical analysis, High-level radioactive waste repository, Disposal efficiency, Rock mass stability
T09: Long term behaviour of underground structuresArash BARJASTEHKhuzestan Water & Power Authority (KWPA), Islamic Republic of IranGeological control on the operational behavior of Masjed -e Soleyman Dam, IranThis article is aimed at study the role of geology on the recent behavior of Masjed-e Soleyman (Godar-e Landar) Dam in Khuzestan Province, south west of Iran. The dam which is a rock fill type has a height of 177 m with a 230 million-m³ reservoir. The foundation rock of the dam is composed of sandstones and conglomerates. Andeka active fault in the north of the dam site is a major structure that affected the dam site geology. Recent monitoring data indicated that powerhouse and transformers caverns suffer severe high stresses on their roofs due to swelling of a claystone layer atop the caverns. Excessive rock mass displacements which caused shotcrete cracking and bolt failure can be seen in some parts of the powerhouse cavern. This article discusses the possible relationship between the geological setting and the observed problems with special emphasis on the powerhouse cavern. | Operational behavior, geologic structure, lithology, Andeka Fault
T09: Long term behaviour of underground structuresChunping WANG (1), Liang CHEN (1), Jian LIU (1), Xingguang ZHAO (1), Ju WANG (1), Jianfeng LIU (2)1: Beijing Research Institute of Uranium Geology, Beijing, China; 2: Sichuan University, Chengdu, ChinaExperimental study and damage-mechanism-based modelling of creep behavior of fractured graniteExperimental investigations on creep behavior of fractured granite have been performed under multi-step stresses. The significant stress effect on the creep strain rate is presented. A coupling damage of the initial macroscopic damage of fractured granite and the microscopic damage induced by external load is deduced. A damage-mechanism-based creep model for fractured granite has been proposed by introducing the damage evolution in the constitutive relations. The model parameters are determined by fitting the experimental results of the time-dependent deformation of fractured granite. It is indicated that the creep constitutive model proposed can provide a precise description of the full creep process in fractured granite under different stresses. The Burgers model is indicated to be a special case of the damage-mechanism-based creep model. | Fractured granite, creep model, damage, fractional derivative
T09: Long term behaviour of underground structuresJintong ZHANG (1), Zhihong ZHAO (1), Junyu CHEN (1), Xingguang ZHAO (2), Ju WANG (2)1: Tsinghua University, Beijing, China; 2: Beijing Research Institute of Uranium Geology, Beijing, ChinaNumerical simulation of nuclide transport at the underground repository scale subjected to thermal loadingThe nuclide transport with groundwater in the fractured rock is always the primary concern during the long-term operational life of underground repositories. The present paper intends to clarify the effects of thermal loading on in-situ stress, groundwater flow and solute transport at the repository scale. A three-dimensional repository model is built up incorporating a vertical fault and a horizontal fracture. The evolution of temperature, stress, aperture, flow velocity and nuclide transport at different time scales is analyzed and discussed. The thermal disturbance induces a significant distribution of temperature and contributes to the increased stresses in the rock matrix. The fracture and fault dominated convection and hydrodynamic dispersion are disturbed by the reduced aperture and the slow flow velocity around the repository. The nuclide transport is retarded under thermal loading conditions. The higher thermal conductivity in the repository induces to faster thermal decay and ultimately facilitates the nuclide transport. | Nuclear waste repository, Nuclide transport, Thermal loading, Fracture, Thermal conductivity
T09: Long term behaviour of underground structuresAli RAZGORDANISHARAHI (1), Maximilian SORGNER (1), Adolf Bernd MORITZ (2), Thomas PILGERSTORFER (3), Bernhard L.A. PICHLER (1), Christian HELLMICH (1)1: Institute for Mechanics of Materials and Structures, TU Wien (Vienna University of Technology), Vienna, Austria; 2: OeBB-Infrastructure AG, Graz, Austria; 3: Geoconsult ZT GmbH, AustriaInvestigating the impact of viscoelastic material models for accurate stress estimation in precast concrete tunnel segmentsThe segmental tunnel lining of Koralmtunnel in Austria is equipped with state-of-the-art structural health monitoring methods. Vibrating wire strain gauges measure histories of normal strains at specific locations along the steel reinforcement of precast concrete tubbings. To translate these strains into normal stresses, viscoelastic behavior of concrete needs to be considered, and a Boltzmann-type convolution integral needs to be solved. In order to quantify the needed relaxation function of concrete, its creep function is represented in a format that distinguishes between short-term and long-term portions, linked to a power law and logarithmic law, respectively. This function is converted into the corresponding relaxation function. It allows for translating measured strain histories into stress evolutions. It is shown that accounting for relaxation of concrete is crucial for long-term stress quantification in segmental tunnel linings. Linear elastically quantified stresses overestimate linear visco-elastically quantified stresses by 75% already three years after tunnel ring installation. | precast concrete, viscoelastic material model, creep function, strain measurements, strain gauges
T09: Long term behaviour of underground structuresRui HUANG (1,2), Takafumi SEIKI (1), Qinxi DONG (3), Shizuo NOGUCHI (4), Takeshi OHMURA (4)1: Utsunomiya University, Japan; 2: Xihua University, China; 3: Hainan University, China; 4: Kawasaki Geological Engineering Co. Ltd., JapanConsideration to evaluate maintenance process for utilization of non-supported underground quarriesIn this study, the authors focus on propose evaluation chart for checking stability and safety the underground quarries because of the underground quarries are unstable and worried about the corrupts. Additionally, it is necessary for those users, such as entrepreneurs to evaluate the stability of the underground spaces in case of utilizing those underground spaces in certain purpose. Field survey is very important and necessary to understand for the workers and entrepreneurs. Thus, the authors consider the stress distribution and deformation to simulate active and abandoned underground quarries. the authors will consider stability for individual structure of room and pillar type based on the numerical analysis with considering influence of adjacent underground spaces. Finally, the authors will discuss the maintenance process to utilize the underground quarries analysis. | underground quarry, stability and utilization assessment, field survey, numerical analysis
T09: Long term behaviour of underground structuresArka Jyoti DAS, Prabhat Kumar MANDAL, Ranjan KUMARCSIR-Central Institute of Mining and Fuel Research, Dhanbad, IndiaDesign of underground structures and support systems for extraction of inclined coal seamStrata control problems are observed more in dipping coal seams than flat coal seams due to shearing effects, asymmetric failure and stress distribution in inclined rock strata. As most of the pillar strength formulae are derived for the conditions of flat coal pillars, their embracing in the stability analysis of inclined pillars may jeopardize the workings. In this study, inclined pillars are designed by using the strength formulae derived for the inclined pillars. The strength of pillars decreases with the increase in the dip of the coal seams and with the decrease in the acute-angle of the corners of the rhombus-shaped pillars. A parametric study is carried out to quantify the effect of inclination on the failure characteristics of inclined pillars and surrounding rock mass. Based on the study, an adequate size of pillars and an effective support system have been designed for a case study mine. | Inclined coal pillar strength, Dip angle, Yield zone, Asymmetric stress distribution, Support system
T09: Long term behaviour of underground structuresChrysothemis PARASKEVOPOULOU (1), James INNOCENTE (2), Mark MCDONALD (2), Mark DIEDERICHS (2)1: University of Leeds, United Kingdom; 2: Queen's University, CanadaTime-dependency and long-term strength of rocks in brittle underground environments – from the lab results to numerical continuum analysisThere has been a wide effort to develop constitutive models to aid prudent engineers or scientists in understanding materials' behaviour in rock mechanics. Hoewever, there is still a lot of work to be done when considering time-dependent behaviour that can lead to instabilities and progressive failures which cannot be captures when considered the commonly used constitutive models, usually static. This paper aims to provide more insight into understanding time-dependent behaviour at both the laboratory and excavation scale. Building on the findings this study develops in-depth understanding on capturing the time-dependent behaviour in brittle rock materials proposing a new approach to be adopted when simulating numerically this behaviour highlighting key considerations both at the laboratory and tunnel scale. | long-term behaviour, time-dependency, time-to-failure, creep, strength degradation
T09: Long term behaviour of underground structuresM. Cristina SACEANU (1), Adriana PALUSZNY (1), Robert W. ZIMMERMAN (1), Diego MAS IVARS (2,3)1: Imperial College London, London, SW7 2AZ, United Kingdom; 2: Swedish Nuclear Fuel and Waste Management Company (SKB), Solna, Sweden; 3: Royal Institute of Technology (KTH), Stockholm, SwedenEvolution of spalling-inducing fractures around a deep geological repository for nuclear waste during glaciations and their effect on the long-term repository stabilityThis paper studies the potential impact of glaciations on the deposition boreholes of the future deep geological repository for nuclear waste at Forsmark, Sweden. A multiple-borehole numerical model is considered, in which fracture growth leading to spalling is simulated in three-dimensions, using the Imperial College Geomechanics Toolkit, a finite element-based discrete fracture growth simulator. Fractures initiate in tension due to in situ stress redistribution after drilling, and grow based on stress intensity factors computed at fracture tips. Glaciation is modelled through its effect on the horizontal stresses determined by ice-crust-mantle simulations, and the vertical stress is determined by the weight of the overlying ice sheet. Numerical results indicate that changes in the in situ stresses influence nucleation and growth patterns, increasing the extent of the damaged rock around the deposition boreholes during the glacial cycle. | deep geological disposal, nuclear waste, spalling, numerical modelling, glaciations
T09: Long term behaviour of underground structuresHlomani Glen MTHOMBENI, Shane K. DURAPRAJ, Richard T. MASETHESibanye Stillwater, South AfricaCrush Pillars’ Behaviour at Intermediate Depth on Merensky ReefThe Siphumelele Mine orebody has been mined extensively up to a depth of up to 1400 m below surface. Apart from stope support, stability of the reef horizon is provided by regional stability pillars support as well as local “crush pillar” support. These pillars are designed so that they crush as they are being cut, with the residual strength of the pillar material being used for the design. However, the major challenge is to “cut” or mine these pillars to the designed size. Undersized pillars degrade and do not provide the required stability, whilst pillar bursts may occur from oversized pillars. Correctly cut pillars perform as expected; they fracture and provide the necessary support. | Crush pillars, w:h ratio, rockburst, support
T09: Long term behaviour of underground structuresSoshi NISHIMOTOCentral Research Institute of Electric Power IndustryLaboratory measurement by geotechnical centrifuge of long-term behavior in a model of vertical emplacement concept with tunnel at a deep geological disposal repositoryWe carried out the centrifuge model test to evaluate the long-term behavior during the resaturation surrounding the deep geological disposal repository. The centrifuge model is the vertical emplacement concept repository and 1/50-size, and the sedimentary rock is drilled a single disposal tunnel and hole, and then the model-overpack, Na-type bentonite buffer, and backfill material are placed in. And the test was conducted at 50 G with the effective stress of 3 MP for equivalent to about 200 years based on centrifugal similarity law. As a result, the displacement of the overpack was measured to be several times larger than that of the tests without the backfill material and disposal tunnel. In addition, it was confirmed that the buffer significantly expanded to the disposal tunnel after the test and visual confirmation. Test results implied that the displacement of the overpack is affected by the stiffness of the backfill material. | Deep geological disposal repository, Long-term THM behavior, Centrifuge model test, Geomechanical interaction
T09: Long term behaviour of underground structuresHermann HÖLD, Bernhard PICHLER, Helmut RECHBERGER, Philipp ASCHENBRENNER, Christian HELLMICHTU Wien (Vienna University of Technology), Vienna, AustriaDissolution and precipitation processes governing the hydration heat development in tunnel cements: Green’s function-based estimation of heat release in modified calorimetric testsCement hydration in freshly installed NATM-linings may imply significant temperature rises, as has been monitored during the advance of the Granitztal tunnel, as part of the high-capacity railway corridor linking the Baltic and Adriatic regions. These temperature rises affect the overall thermo-chemo-mechanical behavior of the lining and its surroundings, which can be elucidated by a coupled analysis method combining the laws of thermodynamics for chemically reactive media with advanced constitutive modeling and structural mechanics. A key material property entering such computations is the hydration heat per mass of cement, which is the focus of the present contribution. We present a modified calorimetry test where the absolute temperature is measured directly at the boundary of the hydrating cement paste sample prepared in accordance with the provisions at the Granitztal tunnel. This modified calorimetry test give access to the instant heat release rate arising from the hydration process. | Tunnel, Cement, Hydration, Calorimetry, First Peak