Local variation of foliated nature of the rock mass can have a significant effect on mining slope design and it is often difficult to predict. This provide concern which should be considered for pit design and continuously monitored during the mine development. This paper describes the huge challenge that was to build the final southeastern wall of the Irene pit pushback by mitigating the risk of slope failure caused by spatial variability of the foliation orientation, knowing that previous mining in this sector of the pit had caused a multi-bench failure of 140 m high and 200 m wide. The developed methodology based mainly on the design conformance analysis, the televiewers investigations, the modification of blasting procedures and the photogrammetric mapping permitted to achieve optimal slope and to continue mining safely.

Deep geological repositories are being designed to manage spent nuclear fuel of past and future reactors for up to 1 million years across the world. The geosphere surrounding a repository should be structurally stable against geological perturbations, such as earthquakes. Previous studies have evaluated earthquake effects on the repository showing that, there is a measured change in excavation damage zone due to a low probability earthquake event. However, a quantitative study has yet to be performed considering extreme events. In this study, a two-dimensional model was developed in RS2, from Rocscience, a finite element package and compared to a previous repository seismic model. The model utilized a Voronoi joint network around the repository to represent a crystalline rock formation (host rock) and allow for excavation induced damage to evolve during construction. The host rock as well as the engineered barrier system were then subjected to glacial induced stress and earthquake loading. This model was then used to perform a statistical study using analysis of variance (ANOVA) to quantify the earthquake effects. The ANOVA analysis (significance level of 0.05) examined normal and shear stresses and displacements along the Voronoi joints after earthquake events of different seismic coefficients (model coefficients used to represent the peak ground acceleration as a fraction of the acceleration due to gravity), relative to the model with no earthquake events and no glacial loading. Glacial loading caused additional damage in the repository excavation damage zone and had statistically significant effect on joint normal stress. The seismic coefficients had no statistically significant effect on the joint parameters, although only the final state after the earthquake loading was investigated. Future research will examine the dynamic loading response during an earthquake.

Maximum horizontal in-situ stress is often analytically calculated using linear elastic theory based on circular boreholes affected by the impacts of drilling events (the development of borehole breakouts or induced fractures) and pressure-time data from a leak-off test or a hydraulic fracture test. However, in the development of unconventional resources, it is noted that shale formations often deform in a time-dependent manner, and the borehole will become non-circular after deformation. Therefore, circular-borehole-based linear elastic analytical solutions are not always appropriate to solve field problems. This paper proposes a new method of in-situ stress inversion from calipers logging data with original borehole size considerations and the time-dependent behavior of shale rocks.
In this research, a three-dimensional poro-visco-elastic FEM model is developed to extend the standard simplified two-dimensional plane strain model to analyze shale deformation. A generalized Kelvin rheological model is used for modeling the visco-elasticity component of deformation. Analytical equations based on the Kelvin model are developed and used for numerical model verification to overcome the discrepancies and deficiencies of the existing analytical solutions and the theoretical Kelvin model results. In finite element modeling, the original borehole size must be considered, bringing an additional unknown parameter (the scale component) into the in-situ stress inversion process. Therefore, a weighted-sum multi-objective optimization of stress inversion from borehole deformation data using finite element modeling is carried out to estimate the maximum horizontal stress, the corresponding original borehole size, and the timing after drilling.
The integrated methodology will be demonstrated by a field case study to estimate the
adjusted borehole size and the in-situ stresses using borehole deformation information reported from four-arms caliper logs of 21 vertical boreholes in Duvernay formation in Western Canadian Sedimentary Basin.

This thesis is concerned with the issue of the effect of minerals in hard rock, mechanized underground mines. Specifically, given than a rockburst occurs, it quantifies the significance of the factor affecting the severity of the damage. Rockburst is one of the important types of rock mass instability where the magnitude of in-situ stresses are high enough. There are several significant parameters would may affect on severity of rockburst such as the magnitude of in-situ stresses, the effect of discontinuities of rock mass and etc. However, one of the significant parameters is the effect of minerals on the instability of rock during the excavation.
In order to obtain the objectives, more than 1500 Point Load Test (PLT) was applied to the study area (Westwood Mine). Also, 130 UCS tests, 78 Triaxial tests, and 57 Brazillian tests were carried out. Thin section analysis also used for at least 63 different samples from different depth and rock types. Then, Factor Analysis (FA) was first applied to explore the structure of the database, or how all variables associated with the strength of rock correlated with each other, so, the data reduction could be carried out. Quartz, Sericite, Epidote, Amphibole, chlorite, Plagioclase and Biotite were determined to be potential factors that could affect rock mass behavior. The load strength of the PLT was selected as the outcome variable. Then the logistic regression was applied to the data set, in order to determine the probability of failure as well as the weighting factor on minerals. Several statistical results were extracted from the logistic regression and the results showed how the low amount of each mineral can decrease or increase the strength of rock and instability of rock during excavation. The probability of rockburst occurrence in underground excavation with different amounts of minerals also was determined.

For almost a century, rock bolts have become a widely employed method of providing support to excavations in the multi-disciplinary domain of underground construction and mining. Rock bolts serve to help provide stability to an excavation profile through a myriad of techniques, including the transfer of load from the unstable profile to more stable rocks, or the creation of an artificial arch. Research has been conducted to better understand rebar bond performance. Numerous investigations involving in-situ and laboratory testing have been conducted. As well, multiple analytical and numerical models have been developed in order to attempt to simulate the performance of rebar specimens within certain scenarios of ground type and support schemes. This has led to a better understanding of the multiple components, mechanisms and properties associated with such a composite rebar, grout and ground system. Due to practical and technological limitations, an in-depth investigation of the load transfer and continuous stress distribution along a fully grouted rock bolt has been challenging. The advent and application of Fiber Optic Sensors (FOS) in the geotechnical discipline has led to a methodology (developed by the authors) capable of providing a continuous strain profile for rebar support / structural members. Fiber optic technology involving Rayleigh Optical Domain Reflectometry (ROFDR) can be used to determine the strain profile and geo-mechanical performance of a rock bolt at an unprecedented scale as well as sampling interval. This paper summarizes such an innovative methodology that has been employed for a series of laboratory axial pullout tests in order to determine the effects of rock bolt rib spacing and borehole diameter on the geo-mechanical response of fully cement grouted rebar rock bolts within simulated rock masses. The results of the research will augment the current body of literature while also improving rock bolt development, design and implementation.

Rock bolts are one of the primary underground support systems utilized to stabilize the rock mass surrounding the opening of excavation by transferring the load from the surrounding rock to the more stable rock mass further from the excavation. Modelling fully grouted rock bolts has been the focus of many researchers due to the difficulties of capturing the interaction mechanism of the interface between the rebar and the grout at the micro-scale. In this paper, two-dimensional numerical simulation has been conducted in order to model the behaviour of fully grouted rock bolts during the pullout tests. Joint parameters of the rebar-grout interface (i.e. shear stiffness, normal stiffness, and peak cohesion) are investigated as well as grout parameters (i.e. Poisson’s ratio and Young’s modulus) in terms of the influence on the rock bolt behaviour. The results indicate that the Young’s modulus of the grout and joint shear stiffness have significant influences on the results. On the basis of these results, the upper and lower limit of strain distribution along with the rock bolt is determined. These results are also compared to the nominally identical laboratory rock bolt pullout tests that have been conducted as part of the physical testing components of the overall research program.