Experimental investigation of rock breakage by a conical pick and its application to non-explosive mechanized mining in deep hard rock

Wang, Shaofeng; Li, Xibing; Yao, Jinrui; Gong, Fengqiang; Du, Kun; Tao, Ming; Huang, Linqi; Du, Shao-lun

doi:10.1016/j.ijrmms.2019.104063

Cited by 179 publications

(80 citation statements)

References 29 publications

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“…Specimens were obtained from small-scale slabs of each rock type without visible geological weakness (e.g., fractures and lamination) [49]. Rectangular prisms with the dimensions of 50 × 50 × 100 mm 3 were first sliced.…”

Section: Specimen Preparationmentioning

confidence: 99%

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

et al. 2019

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The presence of water strongly affects rock properties and would be related to a series of geological disasters. To understand water saturation effects on the mechanical behavior of different rock types and interpret the underlying mechanisms of differences in water sensitivity, three kinds of rocks, namely sandstone, granite and marble, were selected for tests. Uniaxial compression experiments were conducted on specimens under oven-dried and water-saturated conditions. Acoustic emission (AE) techniques were also applied to monitor and record AE signals during tests. Experimental results reveal that water weakens the mechanical parameters of the three tested rocks, such as uniaxial compressive strength (UCS), elastic modulus and critical strain. The sandstone undergoes the greatest weakening with the addition of pore water, the mechanical properties of the granite exhibit relatively minor reductions, while the marble is the least affected by water saturation. The water-weakening degree of rock properties depends on the porosity as well as the mineralogy, especially the proportion of quartz and swelling clays. Moreover, after water saturation, the failure pattern of the sandstone and the granite tends to transform into the shear-dominant mode from the tensile one in dry state, probably due to frictional reduction. However, the water presence does not change the failure mode of the marble.

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Section: Specimen Preparationmentioning

confidence: 99%

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

et al. 2019

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“…(2) When k s ranges from 0.40 to 0.65, though the specimens still remain stable despite of increasing water saturation coefficient, the strain energy releasing rate began increasing rapidly. In deep coal mining, rockburst accompanying fast energy release commonly happens in such a geo-stress level [41][42][43][44]. From Figure 10, water can release the stored energy within the specimen without triggering instability.…”

Section: Discussionmentioning

confidence: 99%

Water Infusion on the Stability of Coal Specimen under Different Static Stress Conditions

2020

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Underground coal mines are frequently subjected to water infusion, resulting in many mining hazards. This study investigated the effect of water infusion on the stress and energy evolution characteristics of coal specimens representing isolated pillars under different initial axial stress conditions using the discrete element method. A water infusion distribution model was developed, in which random functions were employed to describe water distribution for the purpose of realizing the dispersion of results for a better reliability. Based on the results, a stress-level classification was presented to evaluate the water effect on pillars’ instability. For the investigated coal specimens, the water weakening effect on stress and energy remains stable when the axial geo-stress on pillars is less than 65% of uniaxial compressive strength (UCS). In contrast, when the axial stress coefficient is greater than 65%, pillars become unstable eventually. A higher axial stress coefficient is more likely to introduce a lower critical instability point of the water saturation coefficient for pillars in the process of water infusion. However, the instability point remains random to some extent for specimens following the same water distribution rule under the identical test condition. Two instability types, which also happened randomly, were observed in the numerical results for damaged coal specimens under different water saturation coefficients and axial geo-stresses, namely free-falling and step-falling.

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“…In addition, dame sheets should be arranged outside the block wall and at the corner of the transportation roadway and the ventilation roadway of working face #10414. The anchor cable parts should be removed to fully cave the top coal at the corner of the roadway, reduce air leakage, and prevent heat accumulation (Figure ) …”

Section: Discussionmentioning

confidence: 99%

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

Shu

et al. 2019

Energy Science & Engineering

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Mine fires are becoming a serious issue as the intensity of mining increases, especially in deep mines. Loose coal gob has a hidden ignition location and a high possibility of spontaneous combustion, which makes fire prevention difficult. Therefore, based on the theory of gas seepage and the characteristics of loose coal, a model of air leakage and spontaneous combustion in gob is established in this paper. Using working face #10414 in the Yangliu coal mine as an example, the relationship between the three spontaneous coal combustion (CSC) zones and the three stress zones is analyzed and verified by combining a FLAC3D simulation with field monitoring. In addition, the influence of advancing speed on the CSC is discussed, and suggestions for fire prevention are presented. The results show that the variation in the calorific value of the CSC with increasing degree of looseness of the residual coal in the gob forms an arch‐shape. There is a one‐to‐one relationship between the distribution of the three stress zones and the three CSC zones. In addition, as the advancing speed increases, the contact time between the loose coal body and the air decreases and the possibility of CSC decreases. This study provides a scientific basis for fire prevention and control in mines.

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Experimental investigation of rock breakage by a conical pick and its application to non-explosive mechanized mining in deep hard rock

Cited by 179 publications

References 29 publications

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

Water Infusion on the Stability of Coal Specimen under Different Static Stress Conditions

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

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