Uavhengig vurdering av tilbakefylling og anvendelse av avgangsmasser fra planlagt mineralutvinning i Engebøfjellet

SINTEF AS, representert ved forskningsinstituttet SINTEF Community, har gjennomført en uavhengig vurdering av spørsmål stilt av SINTEFs oppdragsgiver tilknyttet tilbakefylling og anvendelse av avgangsmasser fra planlagt mineralutvinning av Nordic Rutile AS i Engebøfjellet, Vestland fylke. SINTEFs vurdering er basert på et utvalg dokumenter og rapporter som er gjort tilgjengelig fra oppdragsgiver, og oppdraget har bestått i å gå gjennom dokumenter gitt i referanseliste, gjennomføre møter, analysere spørsmål basert på SINTEFs kunnskap og erfaring og fremsette SINTEFs funn, kommentarer og konklusjoner i foreliggende, åpne SINTEF-rapport. SINTEFs arbeid er gjennomført av en intern prosjektgruppe med forskere fra SINTEF Community. Vurderinger og konklusjoner er beskrevet i separate kapitler og et innledende kapittel gjengir konklusjonene i kortform.publishedVersio

Development of a 3D structural model of a mine by consolidating different data sources

Joints and faults are inherent parts of the rock mass. In the vast majority of mining slopes, discontinuity structures play an important role in slope stability and may trigger a slope failure. The most important step in understanding the slope failure mechanism is to have a reliable model, which shows how all the discontinuity sets are constituted in the rock mass and how they interact with each other. However, building a fracture model is not a straightforward process, since it needs to combine discontinuity information from a variety of sources, such as detailed slope mapping, borehole logging data and remote sensing technologies. Hence, this manuscript attempts to develop a comprehensive structural model of the complete mine area in an open pit, which is the biggest in Norway with respect to its depth and area of coverage. The manuscript demonstrates on how it is possible to consolidate information from different sources in order to identify typical orientation of the detailed fractures that are associated with the main structural lineaments. The process involves analysis of different sources of data in order to correlate this information into useful evidence about the orientation of the fracture systems in terms of dip and dip direction. Further, the mine is divided into different structural domains and a 3D structural model is developed. As an end result, the domains are kinematically tested with respect to different types of failure modes in both overall slope and bench slope scale of the mine for both a hanging wall and foot wall. It is highlighted here that the results presented in this manuscript are the part of the research project called "Decisive Parameters for Open Pit Slopes (DePOPS)".Development of a 3D structural model of a mine by consolidating different data sourcesacceptedVersionpublishedVersio

Slope stability assessment of an open pit mine using three-dimensional rock mass modeling

Rock mass classification systems are commonly used to evaluate the likelihood of instability in mining environments. Most frequently used classification systems are the rock mass rating (RMR), geological strength index (GSI), and the Q-system. These methods are used widespread among geotechnical engineers as one practical way to assess quality of the rock mass. In most hard rock open pit mines, bench faces with no clear discontinuities present one or two joint sets that may dominate on the failure mechanism. To address this, slope mass rating (SMR), which is a modified version of the RMR system of rock mass classification, can be used. The benefit is that SMR takes into consideration the influence of joint orientation on the classification method itself. Hence, the main aim of this paper is: first, to develop a three-dimensional RMR model of an open pit mine under active operation based on the extensive field mapping carried out, and then produce an SMR surface model that is derived using current topography, modeled RMR values and jointing conditions prevailing in each structural domain. The final goal is to create an SMR susceptibility map of the mine area for the dominant topographic condition and the main structural domains present in the open pit, and to present a methodology that may be easily replicated at any given hard rock open pit mine. The authors emphasize that the use of an SMR model is a very helpful tool in evaluating the areas of the mine that are most vulnerable to potential slope instability in different periods of operation of the mine

Development of a 3D structural model of a mine by consolidating different data sources

Joints and faults are inherent parts of the rock mass. In the vast majority of mining slopes, discontinuity structures play an important role in slope stability and may trigger a slope failure. The most important step in understanding the slope failure mechanism is to have a reliable model, which shows how all the discontinuity sets are constituted in the rock mass and how they interact with each other. However, building a fracture model is not a straightforward process, since it needs to combine discontinuity information from a variety of sources, such as detailed slope mapping, borehole logging data and remote sensing technologies. Hence, this manuscript attempts to develop a comprehensive structural model of the complete mine area in an open pit, which is the biggest in Norway with respect to its depth and area of coverage. The manuscript demonstrates on how it is possible to consolidate information from different sources in order to identify typical orientation of the detailed fractures that are associated with the main structural lineaments. The process involves analysis of different sources of data in order to correlate this information into useful evidence about the orientation of the fracture systems in terms of dip and dip direction. Further, the mine is divided into different structural domains and a 3D structural model is developed. As an end result, the domains are kinematically tested with respect to different types of failure modes in both overall slope and bench slope scale of the mine for both a hanging wall and foot wall. It is highlighted here that the results presented in this manuscript are the part of the research project called "Decisive Parameters for Open Pit Slopes (DePOPS)"

Development of a 3D structural model of a mine by consolidating different data sources

Joints and faults are inherent parts of the rock mass. In the vast majority of mining slopes, discontinuity structures play an important role in slope stability and may trigger a slope failure. The most important step in understanding the slope failure mechanism is to have a reliable model, which shows how all the discontinuity sets are constituted in the rock mass and how they interact with each other. However, building a fracture model is not a straightforward process, since it needs to combine discontinuity information from a variety of sources, such as detailed slope mapping, borehole logging data and remote sensing technologies. Hence, this manuscript attempts to develop a comprehensive structural model of the complete mine area in an open pit, which is the biggest in Norway with respect to its depth and area of coverage. The manuscript demonstrates on how it is possible to consolidate information from different sources in order to identify typical orientation of the detailed fractures that are associated with the main structural lineaments. The process involves analysis of different sources of data in order to correlate this information into useful evidence about the orientation of the fracture systems in terms of dip and dip direction. Further, the mine is divided into different structural domains and a 3D structural model is developed. As an end result, the domains are kinematically tested with respect to different types of failure modes in both overall slope and bench slope scale of the mine for both a hanging wall and foot wall. It is highlighted here that the results presented in this manuscript are the part of the research project called "Decisive Parameters for Open Pit Slopes (DePOPS)"

Assessment on the hydrogeological condition of an open pit mine based on piezometric measurements

Understanding groundwater and flow pattern behavior in a given mine site is generally based on accepted theory related to flow through porous granular media. The existence of discontinuities within the rock mass alters the accepted hydraulic behavior being the joint profile and aperture variability a challenge when designing an open pit mine. In this regard, groundwater interaction with the rock mass is the key variable that influences mining slope design and monitoring. This manuscript studies and analyses the geotechnical perspective of an open pit mine and carries out a comprehensive assessment on the groundwater behavior of an open pit mine in a hard rock environment. The analysis is carried out using data gathered from piezometers and correlating the findings with the structural model of the mine. A comparison of the analysis with the results of previous investigations like hydraulic testing and mapping of the mine site are presented comprehensively. The authors propose the concept of receding time for a better understanding of the drainage capability of a given discontinuity (or a set of them) and its importance in assessing groundwater behavior of the pit slope. Discussions are also made on how groundwater flow can be locally modified by slope scale structures and what are the potential consequences there may have for overall slope stability