Influence of the flooding speed of former lignite open pits on the stability of final slopes

Lazăr, Maria; Faur, Florin; Maria, Apostu Izabela

doi:10.1051/matecconf/202030500040

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…As can be seen, the safety factor was higher when a slope was completely submerged than in the case of the same slope, but partially submerged; this was a result of the manifestation of hydrostatic pressure on the surface of the slope, which acts as a support prism. Analyzing carefully, it can be observed that every time the water level rose on the surface of a slope, the safety factor encountered a significant decrease, followed by a significant increase-the same results were recently observed, according to [49].…”

Section: Discussionsupporting

confidence: 77%

“…The evolution of the safety factor of the final slopes depends directly on the duration of the flooding process [49]. The flood duration depends on the volume of the remaining gap and the available water flow from natural or artificial sources, being defined by the ratio between the two elements: the volume, V, and, respectively, the flow, Q.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the state of stress in the massif and in the dump changes considerably with the beginning of the flooding process of the remaining gap. Water in the lake has a positive effect on stability due to the hydrostatic pressure of the water, which opposes failure [15,19,48,49]. Depending on the physical and mechanical characteristics of the in-situ and waste rocks, it can reach the situation of raising the water level in the rocks (due to the capillary forces), the manifestation of the pore water pressure, and the hydrodynamic pressure which, again, negatively influences the stability.…”

Section: Stability Analysismentioning

confidence: 99%

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A Suggested Methodology for Assessing the Failure Risk of the Final Slopes of Former Open-Pits in Case of Flooding

2021

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Some valuable minerals, such as lignite, are extracted through open-pit mining works. After the cessation of mining activity, large-scale gaps result in the landscape. These gaps, also called “remaining gaps”, represent some of the roughest types of environmental impacts. After the cessation of mining activity, recovery and ecological restoration works are required. However, it is first necessary to carry out risk assessment studies considering the possible future influences on the final slopes. For this study, flooding of the remaining lignite open-pits gaps was considered as the ecological restoration option. The study was based on extensive research, including sampling, laboratory tests, statistical-mathematical processing, hypothesis formulation, evaluations, interpretations, and field observations, regarding the rock behavior and occurrence of negative geotechnical phenomena (geotechnical phenomena that have a negative impact and a risk on the integrity of the environment and local communities, such as landslides, rockfalls, liquefaction, suffosis) during the flooding process. This paper’s originality consists of combining the methods and methodologies developed with the help of classic methods (Fellenius, Janbu, and Bishop methods) and probabilistic ones (Rosenblueth method) existing in the specialized literature for solving the proposed problem and structuring the information similar to a guide.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Stability Analysismentioning

confidence: 99%

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A Suggested Methodology for Assessing the Failure Risk of the Final Slopes of Former Open-Pits in Case of Flooding

2021

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“…Decommissioning the dewatering systems, restoring the aquifer resources, and raising the water level in the lake, influences the stability of the slopes negatively, by manifesting the pore water pressure and/or the hydrodynamic pressure under the conditions of formation of aquifers currents, but also positively by the water pressure manifested on the surface of the slope. Knowing the behavior of rocks in contact with water and the geotechnical risks that may occur in the newly created conditions is essential for increasing the security and safety of objectives and people in areas of influence [31,32].…”

Section: Criterion C6-stability Conditions Of the Final Slopesmentioning

confidence: 99%

A Model to Evaluate the Flooding Opportunity and Sustainable Use of Former Open-Pits

2020

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As a result of open-pit mining exploitations, impressive size gaps occur in the landscape. Their flooding leads to the occurrence of so-called open-pit lakes and represents an interesting way to reclaim and use sustainably the degraded land. In the literature, there are numerous plans, strategies, and guidelines for mine closure and open-pit recovery, but these are usually developed at the regional or national level and offer general suggestions, which must be evaluated and approached case-by-case. Because there is still no way to evaluate the opportunity of flooding the open-pits, a methodology for assessing this opportunity was developed to identify the open-pits that are suitable for flooding, this being the main objective of the paper. The paper is novel because of the multicriteria evaluation of open-pits and their remaining gaps, the logical succession of the criteria, and the proposed concept, methods, models, and equations that allow a complex assessment of the flooding opportunity. The methodology also aims to ensure maximum safety conditions in the former mining perimeter, the socio-economic and cultural requirements of local communities, the harmonization of the land in accordance with adjacent ecosystems, and the sustainable development of the region.

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“…Among them, the most important are represented by the speed and duration of the flooding process, the stability of the in situ and dump slopes, and the geochemistry of the rocks. Some researchers have studied the influence of various factors on the flooding process of the remaining gaps [3], [5], [6], but, generally, particular focus was given to factors in-fluencing slope stability [7]- [10]. Therefore, in this paper, we aimed at identifying the most important factors influencing the flooding process taking into account both the factors influencing the speed and duration of this process and those influencing the stability of the slopes, as they cannot be neglected and safety must prevail.…”

Section: Introductionmentioning

confidence: 99%

Factors influencing the flooding process of former coal open-pits

Lazăr¹,

Apostu²,

Faur³

et al. 2021

Min. miner. depos.

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Purpose. This study aims to identify the main factors that influence the flooding process of the remaining gaps of open-pits comprising essentially the velocity and duration of flooding, but also the stability of in situ and dump slopes during and after the flooding and the water quality in order to ensure the takeover of the future function of the land as soon as possible and the safety of objects and local communities. Methods. Establishing the three categories of factors that influence from a quantitative and qualitative point of view the flooding of the remaining gaps of the open pits. Analysis of the key factors in the flooding process of the remaining gaps, in terms of their contribution to reducing or increasing the flood duration and to reducing or increasing the stability reserve of different types of slopes. Findings. The interdependence and cumulative action of factors that influence the flooding process of remaining gaps and the stability of in situ and dump slopes materializes in worsening the strength characteristics of rocks and changing the state of stress and deformations in the rock mass. Originality. The paper provides a detailed description of the key factors and the interactions between these and their in-fluence on the flooding process, stability, and the factor of safety. Their influence and interactions are highlighted through a case study conducted at the Peșteana mining perimeter level. Practical implications. The flooding of the remaining gaps can cause loss of slope stability during and after the flooding process. Unexpected geotechnical phenomena such as landslides, liquefaction, suffosis, rock falls and/or the water quality of the pit lake can be hazardous to natural and/or anthropic objects and local communities. Safety is essential. Therefore, this study suggests taking into account the most important factors that influence the flooding process when evaluating the floo-ding possibility of remaining gaps. Engineers, researchers, mine planers, local authorities, and students will have essential information and will know when and where special attention will be needed in the case of flooding of former open-pits.

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Influence of the flooding speed of former lignite open pits on the stability of final slopes

Cited by 5 publications

References 2 publications

A Suggested Methodology for Assessing the Failure Risk of the Final Slopes of Former Open-Pits in Case of Flooding

A Suggested Methodology for Assessing the Failure Risk of the Final Slopes of Former Open-Pits in Case of Flooding

A Model to Evaluate the Flooding Opportunity and Sustainable Use of Former Open-Pits

Factors influencing the flooding process of former coal open-pits

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