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ABSTRACT ABSTRACT: Linking resource modeling and geomechanical numerical modeling tools is arguably a step towards a more integrated mine design process. This paper presents a methodology that aims to integrate tridimensional data, modeled through resource modeling tools, into a tridimensional geomechanical modeling code. Numerical experiments are then conducted on the created model. The objective of the experiments is to establish the impact of internal fracturing and fracture degradation on slope stability. 1 INTRODUCTION Nowadays, numerical analyses are performed on a routine basis to study the stability of rock slopes. On the other hand, resource modeling and mine optimization software tools are used everyday to establish the geological resources, ultimate pit and mining sequence for an open pit mine. This paper presents, through a case study, the use of resource modeling tools to define the problem geometrical characteristics within a numerical modeling code. It also presents a series of numerical experiments aimed at establishing the impact of internal fracturing and fracture degradation on the stability of the slope. 2 RESOURCE MODELLING 2.1 Resource modeling tools Resource modeling is at the very core of today’s mining operations. In this case study, the rockmass was modeled using one of the most popular resource modeling and mine planning tools in the mining industry, Surpac Vision, Surpac Minex Group (2006). Ore reserve estimation relies on the analysis of rock samples obtained through diamond drilling. Block modeling is used to represent the spatial distribution of ore grades. Ore grades are interpolated at those blocks, based on geostatistical methods. The size of the selected block is usually dictated by the diamond drilling pattern and the mining bench height. Each block is assigned various properties such as ore grades, level of contaminants, geology and rock properties.
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (0.95)
ABSTRACT ABSTRACT: The paper deals with the geotechnical study and optimum ultimate pit slope design of Ashok opencast project with special reference to the highwall stability of slopes created by surface miner. It was also aimed to know the influence of slope design parameters on the safety factor by sensitivity analysis. Geotechnical mapping was done on the exposed benches of the surface mine as per the norms of International Society of Rock Mechanics. The different geo-mechanical properties of lithological units were determined. The failure analysis was done by GALENA software based on limit equilibrium method and optimum slope design was recommended. 1 INTRODUCTION The geotechnical study was conducted for the optimum ultimate pit slope design of the highwall slopes at Ashok opencast project. The mine is producing 6.5 million tonnes per year. It is located in Jharkhand state of India and being mined by Coal India Ltd. The coal is of non-coking category and is suitable for use in powerhouses. It was also aimed to know the influence of slope design parameters on the safety factor by sensitivity analysis, which tells the importance of the parameter in the critical slope. A more justified and suitable remedial measure can be planned for any critical slope after sensitivity analysis. The geotechnical characteristics of joints in overburden and coal cleats were measured on the exposed benches of the surface mine as per the norms of International Society of Rock Mechanics (ISRM 1978). The different geo-mechanical properties of lithological units were determined at the Rock and Soil Mechanics Laboratories of CMRI. Initially the average orientations of the discontinuity sets determined from the geologic structural mapping were analyzed to assess kinematically possible failure modes involving structural discontinuities in the sandstone as well as coal slope faces.
- Geology > Geological Subdiscipline > Geomechanics (0.88)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.70)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (0.70)
- Well Drilling > Wellbore Design > Wellbore integrity (0.56)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.56)
- Well Drilling > Wellbore Design > Rock properties (0.55)
ABSTRACT ABSTRACT: Design and construction of roads and foundations on steeply dipping slopes and weak bedrock creates challenging rockslope engineering problems because of the kinematic potential for failure into the rock excavations. Nevada Power Company (NPC) is constructing the 83km (50mile) Harry Allen Mead (HAMD) 500 kV power transmission line, their largest. Because ideal terrain was occupied by towers owned by another utility, tower pad HAMD 24/1 and access road had to be constructed on the dip slopes of the adjoining ridge. The slopes created design problems because they dip unfavorably into the excavation creating potentially large planar failures and rockfall. During construction NPC encountered engineering and geological challenges, which necessitated design modifications: adversely dipping rock structure, very weak and fractured unstable rock, rockfall, backbreak from preshear blasting, and poor bonding of resin grout. To stabilize the backwall of the tower pad and road, over 1311m (4300 ft) of rockbolts and dowels were installed. 1 INTRODUCTION 1.1 Project The Nevada Power Company (NPC) is constructing the Harry Allen Mead (HAMD) 500 kV power transmission line, NPC’s largest. Los Angeles Department of Water and Power (LADWP) owns a high power transmission line that traverses prime terrain in a pass formed from the shoulder of Lava Butte and the steeply dipping limestone slope of the Horse Spring Formation (Figs. 1-2). The new power line parallels the line operated by LADWP. However, because the present power line occupies prime terrain in the pass tower pad HAMD 24/1 and access road had to be constructed on the dip slope of the adjoining ridge. To achieve the proper tower pad and access road size, vertical cut slopes were proposed. These dip slopes created rockslope design problems in that the slopes dip unfavorably into the excavation of the proposed structures creating potentially large planar failures and rockfall.
- North America > United States > California > Los Angeles County (0.74)
- North America > United States > Nevada > Clark County > Las Vegas (0.41)
- Geology > Geological Subdiscipline > Geomechanics (0.68)
- Geology > Rock Type > Sedimentary Rock (0.52)
- Energy > Power Industry (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Transportation > Ground > Road (0.78)
ABSTRACT ABSTRACT: This paper reports some results from a study of toppling as a truly three-dimensional (3D) problem using physical models and 3D Discontinuous Deformation Analysis (DDA). A series of physical models consisting of blocks corresponding to different combinations of variables was built to study the effects of these variables. The same models, as well as ones modified by adding lateral confinement, were analyzed using 3D DDA. The physical modeling and 3D DDA results show that the tendency for toppling becomes greater if the blocks are taller for the same base width, if the friction angle of all joints is larger, if the base inclination is larger, and if there is no lateral confinement. For the cases studied, 3D DDA results agree well with the physical modeling results not only in terms of the effective failure mode but also in terms of the displacement histories of the blocks in the model. 1 INTRODUCTION A jointed rock slope is susceptible to failure by toppling if the joints dip steeply into the slope. For toppling to be kinematically feasible, it is usually assumed that the strike of the steeply dipping joint set is roughly the same as that of the slope face. Therefore, the problem can be reduced to a twodimensional (2D) one that can be analyzed by considering a section perpendicular to the slope face. Existing kinematic tests for toppling usually allow for some deviation from the condition that the strike of the joint set is the same as that of the slope face (same-strike condition). For example, the kinematic test for toppling using stereographic projections in Goodman (1989) implies that for toppling to be kinematically feasible, the strike of the joint set must not differ from the strike of the slope face by more than 30 degrees.
- Research Report > New Finding (0.49)
- Research Report > Experimental Study (0.35)