High wall slope stability assessment of open pit coal mine- A case study (original) (raw)
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Current Science
In this study, in situ multichannel analysis of surface waves was performed to characterize the overburden (OB) layers for Jambad open cast coal mine, West Bengal, India. OB dump samples were also collected and laboratory tests were carried out to evaluate the compaction and strength characteristics. Stability analyses of the OB dump slope and highwall were carried out using the finite element-based software Optum G2 considering the configurations suggested by the Eastern Coalfield Limited, India. The stability was also assessed for seismic loading conditions considering pseudostatic loading. This study concludes with recommendations for geometric configurations of the OB dump and highwall slope.
Geotechnical study and optimal slope design at Lajkura open cast coal mine, India
International Journal of Rock Mechanics and Mining Sciences, 2004
The paper deals with a geotechnical study and slope stability of the dragline highwall slope at Lajkura open cast mine. The Lajkura open cast mine is mainly characterized by sandstone, shale and coal. The point load testing of all the formations was done in the field. The bulk density and direct shear tests were conducted at CMRI on the samples collected from the field. The geotechnical mapping was done on the exposed benches of the quarry as per the norms of International Society of Rock Mechanics (ISRM 1978). The different geo-mechanical properties of lithological units were conducted at CMRI. The failure analysis was done by GALENA software. The present study reveals that the 40 m high dragline highwall is likely to be safe. The sensitivity analysis shows that the influence of water is also alarming, hence every attempt should be taken to keep the rain water away from the slope and proper drainage pattern should be effectively maintained.
Scale effect on strength and failure modes of open pit cut slope of Wardha Valley coalfield in India
Stability of slopes is one of the basic problems in open cast mines. Economical and safe open pit slopes involve maximization of the angle of inclination of the slope with proper stability. Studies on stability require a complete knowledge of the local geology. Stability of rock slopes depends on the scale of the slope, type of rock, orientation and density of the discontinuities etc. With an increase in size of rock mass, the chances of presence of joints and fractures increases and hence the strength of the rock material reduces due to the inclusion of more discontinuities in the rock mass. In the present study, a mine slope at Wardha Valley Coalfield in India has been numerically analyzed to take into account the effect of number of joint sets on the stability. The results show a reduction in factor of safety with an increase in joint sets.
Journal of Applied Geology, 2022
The research area was located in the west pit of the open pit coal mine of PT. Tawabu Mineral Resource (TMR) in Bengalon District, East Kutai Regency, East Kalimantan Province, Indonesia. Several landslides drove the research in the area; however, the remaining slopes' engineering geological conditions and stability have not been evaluated. This study's objectives were to understand better the engineering geological conditions and stability of the research area. The geological engineering conditions (i.e., geomorphology, rock and soil, geological structure, and groundwater conditions) were evaluated by photogrammetric analyses, field observations, and analyses of borehole logs and laboratory test results. The slope stability analyses were first carried out by conducting back stability analyses of failed slopes on the northern lowwall slope segment. The shear strength parameters obtained from the back analyses were then used for forward stability analyses of the remaining 10 lowwall and highwall slopes. The slope stability analyses involved deterministic and probabilistic analyses, under static and dynamic, using the limit equilibrium method (LEM). The results showed that the research area and the surroundings consisted of two geomorphological units: the alluvial plain and structural hills. Rocks in the study area consisted of claystone, sandstone, and coal with a general layer strike direction of N59°E-N63°E with a dip of 19°-26°. These rocks were grouped into two lithological units: alternating sandstone and claystone unit, and alternating claystone and coal unit. The geological structures were identified on the highwall, from west to east, namely a major sinistral shear fault with a relative direction of NNE-SSW, two minor sinistral shear faults with a relative direction of NE-SW, and a major dextral shear fault with a relative direction of NW-SE. These geological structures were interpreted as being formed by the folding process. The groundwater level was estimated at-45 m to 20 m. The slope stability analyses showed that only the East HW-4 slope, located on the east highwall, was unstable. It is recommended to optimize the slope by either lowering the groundwater elevation by 4 m from the actual level or by reducing the overall slope angle to 31°.
New Approach to Assesment of Slope Stability on Working Bench in Open Coal Mines
2011
The main purpose of this paper is to analyze the stability of the open coal mine "Suvodol" in Southwest Macedonia, during the past two years (from April 2009 to December 2011), also to represent one new approach for assessment of slope stability of working benches on open coal mines.In the first half of 2009 the open pit mine had an alarming situation where the whole bed moved about 1 cm per day from the Southeast towards to the Northwest so that this situation be conveyed directly in the operation of this mine. To resolve this situation needed further analysis of the stability of the working benches, development of new work plans of method of excavation of coal and overburden in mine and very carefully monitoring the situation on the ground and monitoring the system of cracks that had occurred this time. In this paper will be performed comprehensive analysis of 8 distinctive profiles. We used the information from monthly reports of geotechnical stability of excavated blocks in the period April 2009 to December 2010. New analyses will be done with four regression analysis: linear, polynomials of second and third degree and logarithmic, obtained analytical expressions of the stability factor as a function of time. Overall, stability in the open coal mine during data were taken for analysis (the period provide with trend analysis), is with the value of ratio of stability to almost all sections, of under 1, and going month after month, with a slight increase up even above 1.3 (an increase by 40%). This trend coincided with the trend analysis of new approach made in research analysis in this paper.
Trend analysis in assesment and prediction of slope stability in open coal mines
2011
Geotechnical analysis of the condition of slope stability of excavation blocks in the open coal mine allows to define the safety assessment and prediction of the ongoing process of exploration and planning in future development. Subject of research in this paper will be geotechnical analyze of working environment covered with everyday exploitation and already completed benches. In this paper will be performed comprehensive analysis of several distinctive sections. We used the information from monthly reports of geotechnical stability of excavated blocks in the period from April 2009 to December 2010. The primary goals of the research area is a function of calculating, assessing, analyzing and prediction the geotechnical stability of final slopes of the coal open pit mine. Accordingly, the goals of the research in this paper, in accordance with the basic task of main plane of the coal mine, will be:-Determination of the coefficient of stability;-Assessment of the stability of excavation blocks;-Analysis of the slope stability of working and final benches;-Trend analysis and prediction of assessing the slope stability and-Conclusion and suggestion for further research
India is one of the largest producers of coal in the world with 89% of production coming from opencast mines. Opencast mining operation involves excavation of waste rock i.e. rock formations overlying the coal seams and coal from highwall. Majority of waste rock is back-filled to the de-coaled area and remaining part is dumped outside quarry as external dump. To minimize the amount of rock excavation from highwall, a steep slope of highwall needs to be maintained. The backfilling of waste rock in a limited space of de-coaled area and also outside quarry makes the backfilled dump and external dump slope steeper. Hence, slope stability study of highwall and waste dump embankment needs to be carried out for maintaining safety and economics of the mine. Determination of representative values of shear strength parameters of waste dump and highwall which is not covered in standard soil mechanics and rock mechanics text book is a pre-requisite for stability analysis. This paper presents the methodology of determining representative values of shear strength parameters of highwall and waste embankment.
Geomechanical Stability of Slopes of the Surface Coal Mines of the Main
DergiPark (Istanbul University), 2016
The subject of this paper is the analysis of the geo-mechanical stability of slopes of the surface coal mines of the main geometry factors. Its main purpose is to define the interaction between the geological environment and the engineering activity. Therefore, in solving this problem all available documents from the previous researches and examinations for obtaining more credible and relevant data are used. Because of the above mentioned, the thesis shall obtain the following analyses: Description of the existing situation from geological aspect; Application of various numeric and graphical methods; Selection of most optimal geomethric parameters and stability analysis; In general, various methods are used for slope stability analysis. They can roughly be divided into two groups, such as: Border balance methods. In general, the slope stability analysis consists of the following components: Safety Factor Fs; Slope-Geometrical properties; Physical-mechanical properties of tested soil materials; Groundwater. The stability calculation shall be conducted by various methods with the software packages GGU Stability (BISHOP, JANBU). Discovering the right measure and the exact ratio between the advantage and the limitations of a given method is possible only through appropriate methodological approach, where aspects relevant to specific problems in geotechnical engineering shall be analyzed. Following significant results occurred from the work on this doctoral dissertation: 1) Analysis and sensitivity evaluation of the safety factor in the change of the values of certain geo-mechanical parameters. 2) Critical review of the selection of methods for geo-mechanical stability analysis;
2013
Designing of a stable overburden disposal slope is vital in large opencast coal mines. Spoil generated during extraction of coal which is dumped externally requires larger land to remain stable and also poses problems to surrounding environment due to limited land availability. This has lead to the preference of internal dumping in which the waste is dumped in de-coaled region which is beneficial during extraction and reclamation of mine. Internal dumping is also the most economical and environment friendly method of waste disposal and is being adopted everywhere. It has certain limitations and inherent dangers of failures posing operational and safety threats. In this paper, a numerical study for stability of 80 m high internal dump slopes from an opencast coal mine of
AN INVESTIGATION ON MINE OVERBURDEN DUMP SLOPE STABILITY
IRJET, 2022
In the present study, an attempt has been made to evaluate the safety and stability of mine overburden dump slopes. The influence of addition of geogrids, on the overall stability of the slope has been further discussed. Influence of additional parameters, such as slope height, number of geogrids and their numbers, on the overall stability, has been assessed by performing a rigorous parametric investigations. Upper bound finite element limit analysis technique has been used to obtain the factor of safety of the slopes. The samples are collected from several different overburden slopes, located in the Dhanbad district of India. The basic engineering parameters are evaluated in the laboratory and are further used for numerical modelling. Based on the results obtained, the significance of addition of geogrids, to enhance the stability of mine overburden dump slopes, has been established. Furthermore, the optimum numbers of geogrids, as well as the optimum spacing of the geogrids are also obtained. The present study would be highly beneficial for practicing civil engineers, designing the mine overburden slopes in coal rich regions, such as Dhanbad.