Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Tianhui, Ma; Wang, Long; He, Qingyuan; Tang, Chun’an

doi:10.1155/2016/6195482

Cited by 10 publications

(5 citation statements)

References 17 publications

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“…Coal is a highly heterogeneous material [43]. Its heterogeneity affects rib pillar strength [44] and also makes the coal outburst threshold more difficult to be quantified [45].…”

Section: Stress Distributions During Next Panel Retreatingmentioning

confidence: 99%

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

et al. 2018

Energies

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Abstract:The gob-side entry layout is popular at two-entry longwall mine sites in China for the benefit of improving the coal recovery rate. Currently, two methods have been widely used to develop gob-side entries, including gob-side entry retaining and gob-side entry driving. Gob-side entry retaining maximizes the recovery rate by pillarless mining but increases the difficulty in gob-side entry support. Also, this method has limited applications in hard roof conditions. The gob-side entry driving mine site uses the rib pillar to separate the gob entry and the gob area of the previous panel, which leads to additional coal losses. The waste is more intolerable in large-cutting-height panels and longwall top coal caving panels as the Chinese government limits the minimum recovery rate of longwall panels using these mining methods. In this paper, a new gob-side entry layout method, termed gob-side pre-backfill driving, is established to overcome the shortcomings of the existing methods. The new method eliminates rib pillar losses and enhances gob-side entry stability. The feasibility of gob-side pre-backfill driving is studied by numerical modelling and a field trial at Changcun Mine in China. The results indicate that gob-side pre-backfill driving is an alternative for gob-side entry development. This method is practical and also has the potential to bring significant economic benefits to the mining industry.

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“…Coal is a highly heterogeneous material [43]. Its heterogeneity affects rib pillar strength [44] and also makes the coal outburst threshold more difficult to be quantified [45].…”

Section: Stress Distributions During Next Panel Retreatingmentioning

confidence: 99%

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

et al. 2018

Energies

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“…Indeed, stress environments and pillar size and other factors are very challenging to be investigated by deterministic approaches (Mortazavi et al 2009). Benefitting from the advance of computer technology and the improvement of machine abilities, numerical simulation technology has been applied to help understanding the mechanism of pillar failure by quantitatively analyzing the impact of possible rock properties (Mortazavi et al 2009;Ma et al 2016;Arthur et al 2016;Renani and Martin 2018;Kim et al 2019;Kumar et al 2019). Although the results of a small number of numerical simulations do not necessarily match the observed pillar conditions due to the inaccurate representation of field conditions and the necessary simplification for the establishment of numerical models, numerical simulation is currently one of the most popular methods in pillar stability analysis and research.…”

Section: Introductionmentioning

confidence: 99%

Stochastic assessment of hard rock pillar stability based on the geological strength index system

Zhou

Armaghani

et al. 2021

Geomech. Geophys. Geo-energ. Geo-resour.

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Hard rock pillar is a crucial rock mass structure to maintain the stability of underground mine. It needs of special attention to analyze its stability from the point of rock mass quality. In this paper, the geological strength index (GSI) representing the rock mass quality of the hard rock pillar is examined as a new influence factor of stability, and combined with the conventional parameters (uniaxial compressive strength (UCS) of intact rock mass, width of pillar (w), height of pillar (h), the ratio of pillar width to its height (w/h)) to complete the stochastic assessment of the stability of hard rock pillar. The 47 actual cases of hard rock pillar improved by numerical simulation software Flac 3D . An empirical formula fitted by the Least Square method and artificial intelligence prediction models are used to estimate the pillar strength combining with the pillar stress to conduct the probability and reliability analysis in the Monte Carlo simulation. The result of stochastic assessment showed that UCS and w still play a vital role in maintaining pillar stability, but the influence of GSI cannot be ignored. It found that the GSI has a greater influence on the sloughing pillars in comparison with stable and failed hard rock pillars. Concluding remarks is that GSI has crucial effects on the stability of hard rock pillars as well as UCS of the rock mass and shape of pillars (w and h). Thus, the GSI should be considered as one of input parameter for pillar design and stability assessment in underground mines.

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“…Bai et al [11] investigated roof failure characteristics and stress change rules of gob-side entry driving by stages, noting that a rational protective pillar width could enhance the roadway stability. Ma et al [12] analysed the shear failure behavior for protective pillars and found that the failure mode varied with the pillar width and inclination of the coal seam. Wang et al [13] adopted FLAC3D software to study the dynamic response and failure mechanism of protective pillars; the results showed that enlarging the elastic core in the pillar increased the risk of coal bump.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

et al. 2021

Advances in Civil Engineering

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The width design of protective pillars is an important factor affecting the stability of high-stress roadways. In this study, a novel numerical modeling approach was developed to investigate the relationship between protective pillar width and roadway stability. With the 20 m protective pillar width adopted in the field test, large deformation of roadways and serious damage to surrounding rocks occurred. According to the case study at the Wangzhuang coal mine in China, the stress changes and energy density distribution characteristics in protective pillars with various widths were analysed by numerical simulation. The modeling results indicate that, with a 20 m wide protective pillar, the peak vertical stress and energy density in the pillar are 18.5 MPa and 563.7 kJ/m3, respectively. The phenomena of stress concentration and energy accumulation were clearly observed in the simulation results, and the roadway is in a state of high stress. Under the condition of a 10 m wide protective pillar, the peak vertical stress and energy density are shifted from the pillar to roadway virgin coal region, with peak values of 9.5 MPa and 208.3 kJ/m3, respectively. The decrease in vertical stress and energy density improves the stability of the protective pillar, resulting in the roadway being in a state of low stress. Field monitoring suggested that the proposed 10 m protective pillar width can effectively control the large deformation of the surrounding rock and reduce coal bump risk. The novel numerical modeling approach and design principle of protective pillars presented in this paper can provide useful references for application in similar coal mines.

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Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Cited by 10 publications

References 17 publications

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

A New Gob-Side Entry Layout Method for Two-Entry Longwall Systems

Stochastic assessment of hard rock pillar stability based on the geological strength index system

Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

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