Papers by Michel Aubertin
Calibration of the PM4Sand model for hard-rock mine tailings based on laboratory and field testing results
Canadian Geotechnical Journal
A comprehensive campaign of laboratory and field tests has been conducted to characterize the beh... more A comprehensive campaign of laboratory and field tests has been conducted to characterize the behaviour of tailings from a hard-rock mine. Cyclic triaxial, direct simple shear, and triaxial simple shear tests have shown that the contractive tailings are susceptible to liquefaction and that their behaviour is similar to loose sand despite their higher fines’ content. To model the behaviour of tailings’ impoundments in dynamic simulations, the PM4Sand constitutive model is calibrated based on the dataset presented here. Some of the model parameters are defined based on consolidation and compression tests, while the critical state line (CSL) is defined based on the results of monotonic triaxial and direct simple shear tests. The CSL is lower for tailings than for most natural sands, which is consistent with previous studies. The calibrated model can reproduce reasonably well the monotonic behaviour and provides an excellent fit of the cyclic strength curves measured in the lab at diffe...
Physical and numerical modelling of drainage and consolidation of tailings near a vertical waste rock inclusion
Canadian Geotechnical Journal, 2021
The use of waste rock inclusions in tailings impoundments is a recent technique that offers many ... more The use of waste rock inclusions in tailings impoundments is a recent technique that offers many advantages, but it also raises a few technical issues that must be addressed to optimize their design. A laboratory physical modelling study was conducted to assess the effect of waste rock inclusion on the behavior of initially saturated hard rock mine tailings in terms of drainage and consolidation. The evolution of pore-water pressures and settlements after hydraulic deposition of the fine-grained tailings (slurry), with and without a drainage inclusion, has been monitored and analysed. This investigation also focused on the evolution of the tailings void ratio and volumetric water content, the amount of water transferred to the waste rock, and the movement of fine particles at the interface between the two materials. The experimental results are used to demonstrate how such waste rock inclusion can affect tailings consolidation by reducing pore-water pressures with accelerated water ...
A Viscoplastic-damage Model For Soft Rocks With Low Porosity
A Unified Viscoplastic Model for the Inelastic Behavior of Ice
Field determination of the hydraulic conductivity of a compacted sand layer controlling water flow on an experimental mine waste rock pile
Hydrogeology Journal, 2020
Small-scale infiltration tests were performed on a flow control layer made of compacted sand, ins... more Small-scale infiltration tests were performed on a flow control layer made of compacted sand, installed at the surface of an experimental waste rock pile. The hydraulic conductivity of the sand layer was evaluated from a field investigation using three different testing methods: single-ring infiltrometer, double-ring infiltrometer and Guelph permeameter. The objective was to evaluate and compare the use of these techniques to assess the in-situ hydraulic conductivity of the sand layer. Results from analytical solutions and inverse numerical modelling were also compared. The field approaches gave fairly similar results when the measurements were interpreted with existing approximate solutions, although tests with the Guelph permeameter and single-ring infiltrometer led to slightly higher values of the hydraulic conductivity. The numerical interpretation generally gave lower values for the saturated hydraulic conductivity compared with those obtained analytically, but the differences remain within a factor of 3 or less. The predictive models used in this study, and validated with laboratory measurements, also gave comparable values for the saturated hydraulic conductivity. Any of the three testing methods applied here could, therefore, be used to evaluate the field hydraulic conductivity of the sand layer. Numerical simulations have the advantage of not relying on empirical parameters but require more work with a good estimate of the water retention curve. The investigation also showed that the predictive models used here gave reliable values for hydraulic conductivity when the void ratio was properly determined; such models should however be validated with controlled tests, as was the case here. Des essais d’infiltration à petite échelle ont été réalisés sur une couche de contrôle des écoulements composée de sable et installée à la surface d’une halde à stériles expérimentale. La conductivité hydraulique de la couche de sable a été évaluée sur le terrain au moyen de trois approches expérimentales différentes: l’infiltromètre à simple anneau, l’infiltromètre à double anneaux et le perméamètre de Guelph. L’objectif était d’évaluer et de comparer l’applicabilité de ces approches afin d’estimer la conductivité hydraulique en place de la couche de sable. Les mesures ont été interprétées au moyen de modèles analytiques et de simulations numériques et les résultats comparés. Les différentes approches de terrain ont donné des conductivités hydrauliques relativement similaires lorsque les mesures ont été interprétés au moyen des solutions analytiques existantes; les valeurs obtenues avec le perméamètre de Guelph et l’infiltromètre à simple anneau étaient cependant légèrement plus élevées qu’avec l’infiltromètre à double anneau. Les conductivités hydrauliques obtenues par interprétation numérique étaient généralement plus faibles que celles obtenues analytiquement, mais les différences demeuraient faibles (facteur de 3 ou moins). Les modèles prédictifs utilisés dans cette étude, et validés à partir de mesures de laboratoire, ont également donné des valeurs de conductivité hydraulique saturée comparables. Les trois approches de terrain testées ici pourraient donc être utilisées indistinctement afin de mesurer la conductivité hydraulique de la couche de sable en place. Les simulations numériques présentent l’avantage de ne pas être basées sur des paramètres empiriques, mais nécessitent néanmoins une bonne connaissance de la courbe de rétention d’eau. L’étude a aussi montré que les modèles prédictifs employés donnaient de bons résultats à condition que l’indice des vides soit correctement déterminé; ces modèles doivent cependant être validés au moyen d’essais contrôlés, comme ce fut le cas ici. Se realizaron pruebas de infiltración a pequeña escala en una capa de control de flujo hecha de arena compactada, instalada en la superficie de una pila experimental de roca estéril. La conductividad hidráulica de la capa de arena se evaluó a partir de una investigación de campo utilizando tres métodos de prueba diferentes: infiltrómetro de anillo simple, infiltrómetro de doble anillo y permeámetro Guelph. El objetivo era evaluar y comparar el uso de estas técnicas para evaluar in situ la conductividad hidráulica de la capa de arena. También se compararon los resultados de las soluciones analíticas y la modelización numérica inversa. Los enfoques de campo dieron resultados bastante similares cuando las mediciones fueron interpretadas con las soluciones aproximadas existentes, aunque las pruebas con el permeámetro Guelph y el infiltrómetro de anillo simple condujeron a valores ligeramente más altos de la conductividad hidráulica. La interpretación numérica generalmente dio valores más bajos para la conductividad hidráulica saturada comparada con aquellos obtenidos analíticamente, pero las diferencias permanecen dentro de un factor de 3 o menos. Los modelos predictivos usados en este estudio, y validados con mediciones de…
Etude De L'Anisotropie De La Resistance Au Cisaillement D'Une Argile Sensible Au Quebec
L'ANISOTROPIE D'UNE ARGILE SENSIBLE DE LA MER CHAMPLAIN A ETE MESUREE IN-SITU AVEC UN SCI... more L'ANISOTROPIE D'UNE ARGILE SENSIBLE DE LA MER CHAMPLAIN A ETE MESUREE IN-SITU AVEC UN SCISSOMETRE EQUIPE DE LAMES EN LOSANGE ET RECTANGULAIRES D'ELANCEMENTS DIFFERENTS. LE RAPPORT DES RESISTANCES AU CISAILLEMENT NON DRAINE SUR LES PLANS HORIZONTAL SUH ET VERTICAL SUV VARIE ENTRE 1,50 ET 1,85. UN CRITERE DE RUPTURE ANISOTROPE ELLIPTIQUE REPRESENTE ADEQUATEMENT LE COMPORTEMENT OBSERVE. (A).
Improvement of tailings impoundment seismic and post-seismic stability using densification and waste rock inclusions
Canadian Geotechnical Journal
Tailings impoundments are often prone to failure due to various causes related to complex loading... more Tailings impoundments are often prone to failure due to various causes related to complex loading conditions. For instance, tailings impoundments can fail during or after a seismic event, mainly because of the liquefaction of loose, cohesionless tailings. To improve the seismic stability of impoundments, the density of the tailings can be increased or waste rock inclusions (WRI) can be added in the impoundment. This paper presents the results of numerical analyses of the impoundments loaded with a variety of ground motions with different frequencies, scaled at two different levels of intensity representative of two mining regions of Eastern Canada. The results show that the conventional impoundments are subjected to medium to high displacements at the end of shaking; these show a high probability of rupture during the earthquake or in the post-seismic phase. Tailings densification can decrease the volume of liquefied tailings and displacements during the seismic phase but does not s...
Numerical implementation and application of an internal state variable model to analyze the time-dependent behavior of mining excavations in rock salt
Canadian Geotechnical Journal
The geomechanical behavior of rock salt has been investigated extensively over the years. Experim... more The geomechanical behavior of rock salt has been investigated extensively over the years. Experimental studies have identified distinctive features associated with nonlinear inelastic response that shows strong time and loading history dependencies. In this paper, a relatively simple constitutive model is presented and implemented into the numerical code FLAC, and then applied to analyze the time-dependent behavior of excavations in salt mines. The unified creep-plasticity model includes an internal state variable (ISV) with an evolution law that induces progressive strain hardening (SH) until a steady state is reached. Numerical analyses are performed with the proposed ISV–SH model to evaluate material parameters, based on creep test results on natural rock salt, and to simulate the response of a circular opening and of rectangular mining excavations created in sequence. The results are analysed and compared with those obtained with the well-known Norton power law equation, commonl...
Le présent rapport est une revue de littérature portant sur les divers phénomènes d'interface roc... more Le présent rapport est une revue de littérature portant sur les divers phénomènes d'interface roche-fluide qui induisent des forces endogènes pouvant modifier le comportement mécanique des roches. Les phénomènes étudiés, dits physico-chimiques, sont liés à l'adsorption et à la capillarité des fluides dans le réseau de canalicules (pares et fissures), qui induisent des altérations physiques, comme la réduction de l'énergie libre de surface, et chimique, comme la corrosion et la dissolution. Divers dissolution. Divers facteurs d'influence sur la nature et l'ampleur de ces phénomènes, tels le chimisme du fluide, la composition minéralogique et la structure de la roche, et la température sont présentés et discutés.
Revue Française de Géotechnique, 1999
Mots clés : roche, critère de rupture, écaillage en trou de forage, contraintes naturelles, contr... more Mots clés : roche, critère de rupture, écaillage en trou de forage, contraintes naturelles, contraintes induites.
La methode utilisee pour la construction d’une halde a steriles sur un site minier affecte sa str... more La methode utilisee pour la construction d’une halde a steriles sur un site minier affecte sa structure interne. Les methodes couramment utilisees conduisent souvent a la presence de couches de materiau compacte a l'interieur des haldes, qui sont surtout constituees de materiaux grossiers et lâches. Ces couches, usuellement formees de materiaux plus fins et plus denses, influencent le mouvement et la distribution de l'eau a l'interieur de la halde. Des simulations numeriques a long terme de l'ecoulement non sature de l’eau dans une grande halde a steriles ont ete menees pour etudier l'effet des caracteristiques structurales et du regime des precipitations. Ces simulations, realisees avec le code d’elements finis HYDRUS-2D, conduisent a diverses observations qui aident a comprendre le comportement hydrogeologique de la halde modelisee (sur la base d’un cas reel). Les resultats montrent comment la distribution d'eau et le flux dans la halde sont influences par ...
Experimental Identification of Kinematic and Isotropic Hardening in Rocksalt
An analytical solution for estimating the stresses in vertical backfilled stopes based on a circular arc distribution
Geomechanics and Engineering, 2018
Cryoclastie Des Granulats Mineraux
LA CRYOCLASTIE DES GRANULATS MINERAUX EST ABORDEE D'UNE FACON DESCRIPTIVE AFIN DE CERNER LES ... more LA CRYOCLASTIE DES GRANULATS MINERAUX EST ABORDEE D'UNE FACON DESCRIPTIVE AFIN DE CERNER LES NOMBREUX MECANISMES QUI REGISSENT LA DEGRADATION DES GRANULATS SOUMIS A DES CYCLES DE GEL EN PRESENCE D'EAU. L'ORIGINE DES EFFORTS QUI CONDUISENT A LA DETERIORATION DU MATERIAU EST MULTIPLE. LA FRAGMENTATION DE LA ROCHE SOUMISE A DES VARIATIONS THERMIQUES, LA DESEGREGATION A L'ECHELLE GRANULAIRE DUE AUX CONTRAINTES MECANIQUES GENEREES PAR LA CRISTALLISATION ET L'EXTRUSION DE LA GLACE DANS UN MILIEU POREUX, LES FORCES ENDOGENES DECOULANT DE L'INTERACTION ENTRE LE LIQUIDE DE SATURATION ET LA SURFACE DES GRAINS MINERAUX QUI ABAISSENT LE SEUIL DE PROPAGATION DES FISSURES ET LA RESISTANCE DE LA ROCHE, LES MOUVEMENTS DE LA DOUBLE-COUCHE A L'INTERIEUR DES MICRO-PORES DANS UN REGIME THERMODYNAMIQUEMENT TRANSITOIRE ET LE COMPORTEMENT RHEOLOGIQUE DE LA ROCHE ET DE LA GLACE SONT AUTANT D'ASPECTS QUI SONT ETUDIES DE FACON QUALITATIVE ET QUI ONT UNE CERTAINE INFLUENCE SUR ...
The technique of gamma-ray transmission has been used to measure the variation of the density of ... more The technique of gamma-ray transmission has been used to measure the variation of the density of acidic mine water treatment sludge as it settled in a 15 cm diameter, 180 cm high Plexiglas column. The previous system, using one radioactive source, was upgraded to two sources, 153 Sm with gamma-ray energy 103 keV and 198 Au 412 keV, to determine simultaneously the solids density and the water concentration during sedimentation. The sources and Sodium-Iodide detector scan the column vertically in 20 minutes to measure density profiles. Accuracy of 0.04 g/cm 3 was achieved for both solids density and water concentration in one type of sludge, but the technique failed to distinguish between water and solids in sludge with low heavy metal content. Changing one of the sources to reduce the energy of the gamma-rays from 103 keV to 60 keV should improve the accuracy to 0.02 g/cm 3 for any sludge.
Physical Model Testing and Analysis of Hard Rock Tailings Consolidation Considering the Effect of a Drainage Inclusion
Geotechnical and Geological Engineering, 2021
The use of waste rock inclusions (WRI) in tailings impoundments is a novel technique offering var... more The use of waste rock inclusions (WRI) in tailings impoundments is a novel technique offering various advantages. It is however relatively new and not yet commonly used, so a few key technical issues must still be addressed to optimize the design of WRI. This paper presents an experimental investigation, conducted as a part of a major research program, aimed at assessing the consolidation behavior of tailings during and shortly after hydraulic deposition and the effects of placing a waste rock inclusion in contact with the tailings. The results of a first series of physical model tests performed in an instrumented column with hard rock tailings deposited in successive layers are presented and analyzed to investigate the evolution of pore water pressures, strains and related consolidation parameters at each stage of filling. The results of a second series of experimental tests on tailings with a cylindrical WRI placed at the center of the physical model are then presented and analysed to evaluate how the inclusion influences drainage and pore water pressure at different locations in the tailings. Numerical simulations are also conducted to further assess the consolidation behavior of tailings during sequential deposition and the influence of the WRI. Additional analyses and discussion of the results are also presented to address complementary aspects.
Geotechnical and Geological Engineering, 2020
This paper presents the main results from an investigation into the slope stability of unsaturate... more This paper presents the main results from an investigation into the slope stability of unsaturated waste rock piles with various configurations and surface recharge conditions. The analyses first consider waste rock piles with different internal and external configurations, under steady-state conditions to evaluate the effect of the pile geometry on the factor of safety. Transient analyses are then conducted to evaluate the influence of rainfalls of different intensities and durations. For six waste rock pile configurations, the results illustrate how the external geometry of the pile influences the factor of safety. The results presented here show how surface infiltration (water recharge), external geometry, and internal pile features affect unsaturated water flow, pore water pressure (matric suction), and material strength, which in turn influence slope stability. Despite the relatively large imposed recharges, following major precipitation events, the results indicate that the decrease of the factor of safety FS is relatively small when compared with the effect of other influential factors. The results also demonstrate that the external geometry of the waste rock pile has the most significant impact on the factor of safety, indicating that pile stability can be controlled with an appropriate design. Waste rock piles with a uniform slope (single bench) should be avoided as this construction method leads to the lowest factor of safety. The overall results clearly demonstrate that the best way to improve the stability of waste rock piles is to use a design and construction method with benches of limited size.
Characterization of Self-Weight Consolidation of Fine-Grained Mine Tailings Using Moisture Sensors
Geotechnical Testing Journal, 2018
This paper presents an experimental procedure and testing results on the consolidation of saturat... more This paper presents an experimental procedure and testing results on the consolidation of saturated tailings based on measurements made with moisture sensors. A special calibration procedure has been developed for precise volumetric water content measurements to reflect the progressive change of density and void ratio in the loose tailings. The moisture sensors’ readings are used to evaluate key parameters during self-weigh consolidation, which allow an assessment of the settlement’s rate and magnitude. The results indicate that the proposed technique can be useful to assess the tailings slurry characteristics, which significantly evolve during self-weight consolidation. The experimentally determined parameters are in the range provided by other investigations conducted on the same materials. It is also shown that pore-water pressures deduced from the volumetric water content measurements during the laboratory tests correlate well with the profiles obtained from the one-dimensional consolidation theory.
Consolidation characteristics of hydraulically deposited tailings obtained from shear wave velocity (Vs) measurements in triaxial and oedometric cells with piezoelectric ring-actuator technique (P-RAT)
Canadian Geotechnical Journal, 2020
This paper presents the main results of a laboratory study of the use of shear wave velocity, Vs,... more This paper presents the main results of a laboratory study of the use of shear wave velocity, Vs, to characterize hydraulically deposited tailings on the basis of density (void ratio), mean effective stress, and overconsolidation ratio. Tailings specimens from a gold mine in western Quebec were prepared in triaxial and oedometric cells in a manner that simulates hydraulic deposition. The specimens were consolidated isotropically and anisotropically (stress ratio, K of 0.38). Vsmeasurements were performed at each load increment using the piezoelectric ring-actuator technique (P-RAT). Correlations relating shear wave velocity to the void ratio, confining stress, and overconsolidation ratio of the tailings are presented. These laboratory correlations can be used for the characterization of the tailings by in situ Vsmeasurement. The application of these correlations to seismic cone penetration testing in an actual tailings impoundment is also presented.
Hydrogeology Journal, 2020
Uploads
Papers by Michel Aubertin