The ultra-fine tailings have the characteristics of poor water permeability, long consolidation time, low mechanical strength, and are difficult to dissipate excess pore water pressure. These characteristics lead to problems of dam construction difficulty, poor drainage of embankment, high water content of deposited tailings and low dam bearing capacity. This paper introduces a new method of chemical pretreatment combined with physical treatment of ultra-fine tailings. By adding flocculant, the fine particles in tailings can be combined into coarse particles to accelerate the setting speed and pre dehydrate the ulter-fine tailings. When the solid concentration is up to 20%, the pre dehydrated tailings are filled into a special pore size geofabriform bag made of geotextile. The bag is different size and is preset drainage body inside which can reduce the seepage path and increase the permeability coefficient of the whole bag. Drainage board is laid on the external surface of the geofabriform bag, and vibration load is applied on the drainage board to accelerate the dewatering and consolidation of ulter-fine tailings in the bag. The cost of this method is acceptable. Engineering application indicated that this method has easy site application and the ultra-fine tailings can be disposed in situ.

La gestion des connaissances est un concept né dans les années 90. L'un des principaux objectifs de cette discipline est l'utilisation des pratiques et technologies de l'organisation pour bénéficier des connaissances. Les systèmes de gestion des connaissances se réfèrent à tout type de système informatique qui stocke, traite et récupère des données, quelle que soit leur nature, améliorant ainsi la collaboration, la localisation des ressources de connaissances et, finalement, l'ensemble du processus d'acquisition, de traitement et d’exploitation. En outre, ces systèmes de gestion peuvent également être utilisés pour encourager et superviser les collaborateurs à adopter de bonnes pratiques. Ils permettent aussi de gérer les connaissances utilisées pour connecter les personnes et l'organisation selon les principes de la taxonomie et de l'ontologie. La mise en œuvre d'un système de gestion des connaissances fiable améliore la prise de décision et augmente la productivité organisationnelle. Cette étude de cas reflète le travail de recherche mené au sein du laboratoire de mécanique des roches et géologie appliquée de l’Université de Sherbrooke et porte principalement sur la mise en place d’un outil de système de gestion de connaissances appliquées en géotechnique basée sur une application web afin de répondre aux exigences d’ergonomie et de faciliter la gestion des données. Ce type de système basé sur le web transforme les données brutes accumulées par une organisation en connaissances utiles en collectant des données dans une base de données centrale, en les contextualisant et en les rendant facilement consultables afin que les utilisateurs puissent trouver eux-mêmes les connaissances dont ils ont besoin et ainsi préparer les données pour appliquer des algorithmes d’intelligence artificielle dans des projets de recherche en géotechnique.

Mots-clés : connaissances, outil, système de gestion de connaissances, géotechnique, données, intelligence artificielle.

In many northern Canadian communities, buildings are supported in or on permafrost. Permafrost degradation due to climate warming can impact these building foundations, as well as nearby slopes whose stability often depends on remaining frozen. Community mapping can therefore be a useful strategy in land-use planning.

Two series of maps, describing community surficial geology and geohazards, including permafrost-related geohazards, were compiled with the assistance and support of Ecology North, the Hamlet of Fort McPherson, and the Rat River Development Corporation Ltd., as one of several proposed adaptations to climate change in Fort McPherson that required geotechnical engineering and permafrost expertise. Additional maps were developed to demonstrate changes in slope vegetation (trees and shrubs) over several decades to correlate with areas of slope movements and development. Another map presented a visual slope retrogression analysis and recommended setbacks.

The map series were designed to be desktop-level maps that would accomplish the following tasks:
- Help the community better understand the soils, rock and permafrost conditions around them, including geohazards related to those conditions;
- Provide a tool to assist land managers with land use and development: to determine the preferred areas for building and avoid areas unsuitable for the future development. Using the maps, it will be possible to avoid areas with high ice content and/or organic soils, issues with water on site and thaw settlement, as well as slope instabilities; and
- Provide a baseline reference for monitoring potential permafrost degradation or large-scale changes in the permafrost conditions and/or slope stability, resulting from climate change and/or human-induced impact.

The development of steeply dipping narrow vein ore bodies by using traditional mining techniques is always a challenge and leads to a large stripping ratio for the mining to be economic efficient and high safety risk. The Sustainable Mining by Drilling (SMD) method is proposed to overcome the difficulties in narrow vein mining. In this concept, the dipping narrow vein ore body will be crushed and transported to the ground in the process of the directional drilling. The stability of the wellbores during and after drilling is a critical issue for the safety of narrow vein mining, especially for the hanging wall in highly deviated intervals. In this study, the in-situ stress and other rock mechanics information were collected on the mining site. Then, the wellbore stability was evaluated by using different wellbore failure criteria. The designed maximum depth was 250m; the maximum wellbore diameter was 1.3m; the maximum wellbore inclination was 45 degrees. The results of the wellbore failure criteria were compared. A discrete element method (DEM) simulation was conducted. The DEM simulation result presented a microscope evaluation of the process of rock failure occurrence. Coupling the analytical result and the simulation result, the mud weight for the drilling was optimized as a solution to the highly deviated well interval stability. The risk of wellbore failure was then reduced.

A new innovative method named Sustainable Mining by Drilling method (SMD) is used for mining in which the ore is highly dipped stranded and it is not economic to mine by a conventional method. The SMD method is based on a two-pass drilling procedure using a high torque, high thrust drill rig that is custom modified for the mining equipment. For the first drilling pass, a pilot hole is drilled along the dip of the vein. This hole is directionally steered using downhole geophysical imaging tools to follow a trajectory that is halfway between the hanging wall and footwall contacts of the vein. In the second drilling pass, the pilot hole is opened to the full width of the vein using a large diameter hole opener that follows the trajectory of the pilot hole. The holes will be drilled in primary and secondary sequencing. Primary holes are drilled in the intact rock and secondary holes are drilled between the primary holes. Primary holes need to be backfilled using cemented tailing backfill, while secondary holes do not. In this paper, the mineralogy and grain size distribution tests of tailings are conducted. The procedures and mixture for fabricating the backfilling material for the SMD project are introduced. Two recipes were tested: 100% Portland cement and a combination of 80% Portland cement and 20% fly ash, respectively. During the curing time (28 days in total) of the backfilling material, its increase in strength over time is tested and analyzed at 7 days, 14 days, and 28 days after the casting. At each curing stage, density and unconfined compressive strength (UCS) tests are performed. The relationships between backfill strength and tailing grain size distribution, curing time and the backfill material recipe are proposed based on the experimental results.

The shear strength characteristics are essential part of the hydro-mechanical behavior of unsaturated soils. It is well-known fact that the shear strength of unsaturated soil is related to the hydraulic retention behavior of soils through the soil water retention curve (SWRC). It is believed that the SWRC is highly dependent on the particle size and formation of particles. Consequently, the particle size distribution may affect the overall hydro-mechanical response of unsaturated soils. despite their significant application in geotechnical engineering, the unsaturated shear strength of man-made fine materials such as mine-tailings is less understood. In this study, the conventional direct shear testing procedure is used to assess the unsaturated shear strength characteristic of mine-tailing using the suction stress characteristic framework (SSCF). The characterization of the hydro-mechanical behavior of the mine-tailings is complemented with the determination of the SWRC in an oedometer apparatus with control of matric suction. the experimental data from direct shear tests are compared with the predicted values obtained from SWRC using SSCF. The results indicated that having fine materials does not necessarily dictates residual shear strength similar to clayey soils and SWRC are required to be modified in order to properly model such behavior.

Intermittent dynamic traffic loading is often applied to the soft clay ground in the long-term operation of rail transit. Through literature review, there are still some divergences in what types of loading modes can be used to simulate traffic loading and how loading modes affect the consolidation behavior. So far, there is no reasonable equation in the local code to evaluate the deformation of ground under long-term traffic loading. Therefore, it is important to forecast dynamic consolidation of soft clay ground under the different loading modes. In this study, three loading modes of sinusoidal loading, triangular loading and rectangular intermittent loading was selected. Based on the theory of Terzaghi one-dimensional consolidation, analytic solutions for consolidation of the single-layered ground subjected to sinusoidal loading, triangular loading and rectangular intermittent loading, respectively, have been investigated. Series separation variable method was applied to the solution due to the assumptions of an isotropic elastic material for the ground. Research showed that vibration frequency and stress level played an important role in the pore pressure and the rate of consolidation. To accurately predict the long-term deformation of multi-layer ground under different vibration frequencies and stress levels, the finite element method was used, and different loading modes were obtained by programming of subroutine. The development of deformation and excess pore pressure was also analyzed during dynamic consolidation of multi-layer ground under the different loading modes. Finally, based on simulation results, the empirical formula considering the vibration frequency and stress level was proposed to predict the long-term deformation for different loading modes. By comparative analysis of case study, it was found that the error between the calculated result and the measured settlement value can be controlled within 10%, which demonstrated this formula can be applied well in engineering practice.