Α comprehensive geotechnical characterisation of overburden material from lignite mine excavations

Theocharis, Alexandros I.; Zevgolis, Ioannis E.; Koukouzas, Nikolaos

doi:10.1007/s40948-021-00230-z

Cited by 8 publications

(8 citation statements)

References 21 publications

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“…The decrease of  concomitant with the increase of C is a known phenomenon, verified by analysing the correlation between these 2 parameters (Theocharis et al 2021). The calculation of the correlation coefficient r shows, unsurprisingly, that the anti-correlation values correspond to the values that can be found in the literature (Theocharis et al 2021). The value of r varies between -0.11 and -0.83 with a mean value of -0.37 (Fig.…”

Section: Depth (M)supporting

confidence: 73%

3D large-scale numerical model of open-pit lake slope stability—case study of Lake Most

Renaud

Heib

Burda

2022

Bull Eng Geol Environ

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Almost all post exploitation open pit mines in the world are shaped as a final water reservoir. One of the main hazards is the slope stability of lake banks. To develop a reliability methodology for assessing the long-term stability of flooded open-pit lake, a back analysis was conducted using 2D and 3D large-scale numerical models of Lake Most, which is one of the largest mining lakes in Europe (Czech Republic). The large-scale numerical model was built, based on the site observations, large scale LiDAR data, in situ characterisation tests and statistical analysis of geotechnical data, on DTMs defining the complex geology of the site and on numerous piezometric levels to build the water table . Local and global safety factor (SF) were calculated using the strength reduction method. The results highlighted the reliability of the methodology to combine the geometric model with the geological model to create a large-scale numerical model, to identify local and potentially instable zones and to highlight the role of a weak contact layer. The calculation of 3D SF has shown a very good correlation between the lowest SF and the ground movement observations noted by the Czech authorities.

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Section: Depth (M)supporting

confidence: 73%

3D large-scale numerical model of open-pit lake slope stability—case study of Lake Most

Renaud

Heib

Burda

2022

Bull Eng Geol Environ

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“…In this work, Greek lignite mines are employed for the soil properties that represent fine-grained materials. Theocharis et al [31] recently discussed an overview of the geotechnical characterization of the soil materials found in Greek lignite mines. Nevertheless, these properties are not specific to a site but characterize this type of surface mine slope.…”

Section: The Methodology and The Case Example Of Greek Lignite Minesmentioning

confidence: 99%

“…Finally, the soil's permeability, the main soil property related to infiltration, was parametrically investigated. The chosen saturated permeability lies in the range of the dominant overburden material of Greek open-pit lignite mines [31].…”

Section: Effect Of Rainfall On Slope Stabilitymentioning

confidence: 99%

From Climate Conditions to the Numerical Slope Stability Analysis of Surface Coal Mines

et al. 2022

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A new perspective is presented for evaluating the slope stability of coal and lignite mines due to rainfall. The case of Greek lignite mining areas is employed to illustrate the methodology. Initially, past climatic records of rainfall are documented and analyzed; rainfall intensity varies from light (0.8 mm/h) to heavy (up to 9 mm/h). Few extreme phenomena are documented, with the maximum intensity being 17 mm/h. Furthermore, climatic projections of future trends are performed with open-access tools to anticipate possible deviations from the baseline conditions. Although the mean temperature is expected to increase, projections show that the past rainfall range is not expected to change. Finally, the effect of rainfall infiltration on the stability of a typical open-pit lignite mining slope is investigated by finite element analysis. The precipitation range defined by the environmental analysis is used. The SF is practically constant for the lower rainfall intensities (0.8–2.2 mm/h). For the higher intensities of 6.4 mm/h, 9 mm/h, and 17 mm/h, the SF decrease is almost the same (from 2.08 to 1.9), with reduction rates of 8.3%, 8.9%, and 9.3%, respectively. The effect of the critical geotechnical properties—groundwater table depth, unsaturated zone properties, and soil permeability—is also examined for a complete evaluation.

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“…The comparison was conducted for three weak zone inclinations towards the excavation, 0°, 3° and 6° (unfavourable inclination). For the numerical model, the soil's friction angle and cohesion were φ=28° and c=185kPa (Theocharis et al 2021), while the weak zone's thickness was d z =5m. Note that Mikroutsikos et al (2021) showed that the weak zone's thickness is insignificant for the overall stability.…”

Section: Numerical Model: Basic Assumptionsmentioning

confidence: 99%

“…The friction angle and cohesion of the homogeneous soil layer may vary in a wide range. A recent study shows that the average characteristic peak friction angle and cohesion for Greek lignite mines are 25° and 111kPa, respectively (Theocharis et al 2021). However, for individual mines, these values can be as low as 22° and 20kPa.…”

Section: Introductionmentioning

confidence: 99%

The Evolution of Geotech - 25 Years of Innovation

Hammah¹,

Yacoub²,

McQuillan³

et al. 2021

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I have been teaching and researching rock engineering and practicing as a consultant since 1972. I have spent most of that time in underground mining. I have seen significant changes, both evolutionary and radical, in the sector. In this paper, I reflect on some of these changes in mining geomechanical practice. I will also comment on some of the positive and occasionally less positive impacts of these changes. One constant throughout my career is that geomechanical designs will always be fraught with uncertainty. As a result, we will discuss geomechanical design as being, in its essence, a risk management exercise. I will argue that, as impressive as modern numerical analysis techniques are, they do not on their own mitigate design risk; under worst-case scenarios, they make things worse. Empirical and simple models must be used as a check. The paper intends to provoke healthy skepticism in geomechanics practitioners, designers and managers regarding all the aspects of the geomechanical analysis and design process. A failure to recognize the risks in these processes can have catastrophic effects.

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Α comprehensive geotechnical characterisation of overburden material from lignite mine excavations

Cited by 8 publications

References 21 publications

3D large-scale numerical model of open-pit lake slope stability—case study of Lake Most

3D large-scale numerical model of open-pit lake slope stability—case study of Lake Most

From Climate Conditions to the Numerical Slope Stability Analysis of Surface Coal Mines

The Evolution of Geotech - 25 Years of Innovation

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