Use of an artificial crown pillar in transition from open pit to underground mining

Xu, Shuai; He, Qingyuan; An, Lihui; Li, Yuan Hui; Jin, Chang Yu

doi:10.1016/j.ijrmms.2019.03.028

Cited by 13 publications

(8 citation statements)

References 20 publications

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“…For instance, Hemant et al [18] proposed a multivariate regression model to generate a chart, which enables the design for crown pillar thickness under different geological condition. Xu et al [19] introduced an approach to design the size of the crown pillar by integrating analytical and empirical methods, numerical modeling, and on-site monitoring. e approaches proposed in existing literature studies enable the implementation of a crown pillar with variable thickness between open pit and underground mining.…”

Section: Introductionmentioning

confidence: 99%

“…us, if both surface and underground methods have been decided to be employed, the relationship (zf(0)/zx)＞(zg(y)/zy)＞0 should be satisfied. Second, the size of the crown pillar is assumed to be a constant, but numerous literature studies show such size varies with the rock property and the size of underground void [14][15][16][17][18][19]. To develop the profit of mining projects, as well as to enhance the safety of open-pit slope and underground stope, the variation of the size of the crown pillar is considered in the proposed approach.…”

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confidence: 99%

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Extended Ultimate‐Pit‐Limit Methodology for Optimizing Surface‐to‐Underground Mining Transition in Metal Mines

Ren

Liu

Yang³

et al. 2022

Advances in Civil Engineering

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The transition from surface mining to underground is a critical issue for metal mines. The commonly cited procedure cored by ultimate-pit-limit (UPL) methodology is restricted to maximize the profit from both surface and underground mining, due to the absence of the integration of the profit from either of them. Under the target for such maximization, this study proposes a new optimization approach, which directly relates the design of open-pit limit and underground stopes, by equalizing the marginal profit from either surface or underground mining. The variation of the crown pillar size is involved in this approach. The proposed approach is applied to the Dagushan iron mine, and results show the total profit increased from 3.79 billion CNYs (original design by conventional UPL methodology) to 4.17 billion CNYs (optimal design by the proposed approach), by 9.91%. Moreover, the marginal profit from surface and underground mining, as well as total profit, of all possible designs of surface-to-underground mining transition in Dagushan iron mine is calculated to validate the proposed approach. When the marginal profits satisfy the criterion of the proposed approach, the maximum value of the total profit appears, and this demonstrates the proposed approach is robust to maximize the total profit in surface-to-underground mining transition. This work contributes to existing literature studies primarily from practical aspect, by providing a unified approach to optimize the transition from surface to underground mining.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Extended Ultimate‐Pit‐Limit Methodology for Optimizing Surface‐to‐Underground Mining Transition in Metal Mines

Ren

Liu

Yang³

et al. 2022

Advances in Civil Engineering

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“…Rock slopes could experience the disturbance from various deep mining activities in the process of combined open-pit mining and underground mining. In such deep mining process, the high-stress hard rock experiences various extreme events such as blasting operations, mechanical shock earthquakes, excavation unloading, and other dynamic disturbances around the deep underground rock [9][10][11][12][13][14][15][16], causing the significant change of the stress field and displacement field in the slopes and thus worsening the instability of slopes and landslide [17][18][19][20]. For example, on May 13, 2011, the north side of Shengli open-pit mine in Inner Mongolia, China, experienced a catastrophic landslide, which had a length of about 1.3 km, an area of 0.886 km 2 , and a volume of approximately 85 million m 3 [21].…”

Section: Introductionmentioning

confidence: 99%

“…e rock mass of the deep concave slope in the open-pit and underground combined mining is usually composed of multilayer soft and hard interlayer structural planes, of which the mechanical properties influence the slope deformation characteristics [19,21,22]. A number of studies have shown that structural planes are the main controlling factor in controlling coal slopes' local instability.…”

Section: Introductionmentioning

confidence: 99%

“…MATLAB was used to compile the Chebyshev II bandpass filter in order to filter the wave and obtain the effective waveform frequency.3.3. Dynamic Response Characteristics of the Slope.In order to study the influence of input wave frequency on slope dynamic response characteristics, the displacement and shear strain nephograms of slope under dynamic loads with different frequencies(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) are shown in Figures 4 and 5.…”

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confidence: 99%

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Dynamic Response Characteristics and Failure Mechanism of Coal Slopes with Weak Intercalated Layers under Blasting Loads

Liu

Song

Chen

et al. 2020

Advances in Civil Engineering

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Rock slopes with weak intercalated layers could experience disturbance from various deep mining activities; however, their dynamic stability has not been thoroughly investigated. In this paper, the dynamic response characteristics and failure mechanism of the coal slopes with weak intercalated layers under blasting loads were studied by means of numerical analysis, shaking table tests, and field tests. The effects of dynamic loads with different frequencies on the dynamic response of the slope were analyzed, and the natural frequency of the slope was also determined. The results show that the dynamic amplification effect of the slope is smaller than that of the homogeneous slope, and weak layers weaken the wave propagation in the rock mass. Both experimental and field investigation results show that the slope’s natural frequency was approximately 35 Hz. The slope deformation decreased with the distance of the blasting source. Cracks appear along the weak interlayer firstly under the action of horizontal vibration; then, longitudinal cracks occur at the slope crest. With the increase of dynamic loads, cracks continue expanding, deepening, and penetrating in the main controlled weak interlayer; then, the sliding body presents tensile shear failure along the sliding surface. This study could provide insights into the understanding of the coal slope instability and failure mechanism; this could benefit the blasting operation of the coal slope in fields.

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Numerical Simulation of Crown Pillar Behaviour in Transition from Open Pit to Underground Mining

et al. 2021

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Crown pillars provide regional and local support by isolating the ground surface from underground mine workings. Topography above the underground mine may be a relatively flat ground surface or an open-pit structure. Depending on what lies above and design of the underground mine, the crown pillar behaviour will differ. In transitioning setups (open pit to underground), large open pit collapses have taken place as a result of crown pillars located at the transition zone. Hence, this paper focuses on crown pillars between open pit and underground to better understand their behaviour. Taking the Zuuntsagaan Fluorite mine as an example where open pit will transform to underground mining, a remnant ore is to be left as a crown pillar to separate the two mining sections. Through numerical simulation in FLAC3D 7.0, stress distribution and failure mechanisms acting around the crown pillar were monitored as underground mining progresses. Effect of crown pillar geometrical parameters was evaluated, thus crown pillar thickness, span and dip. Further, the open pit geometry influence was also considered on the overall behaviour of the crown pillar. It was found out that in transition from open pit(OP) to underground(UG), slope and stope walls closing in on the crown pillar induce stresses that act as loading from the pillar sides, which in turn influence the failure process.

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Use of an artificial crown pillar in transition from open pit to underground mining

Cited by 13 publications

References 20 publications

Extended Ultimate‐Pit‐Limit Methodology for Optimizing Surface‐to‐Underground Mining Transition in Metal Mines

Extended Ultimate‐Pit‐Limit Methodology for Optimizing Surface‐to‐Underground Mining Transition in Metal Mines

Dynamic Response Characteristics and Failure Mechanism of Coal Slopes with Weak Intercalated Layers under Blasting Loads

Numerical Simulation of Crown Pillar Behaviour in Transition from Open Pit to Underground Mining

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