Mechanisms Underlying the Slip and Failure of Coal-Rock Parting-Coal Structures Under Unloading Conditions

Liu, Yang; Lu, Cai‐Ping; Xiao, Zi‐Yi; Guo, Ying

doi:10.1007/s00603-022-02919-3

Cited by 5 publications

(3 citation statements)

References 44 publications

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“…Numerous engineering practices, including tunnel excavation, oil and gas eld development and coal seam mining, have resulted in signi cant casualties and property losses. These accidents are closely related to the slip of discontinuous structural planes (Segall, 1989;Ortlepp, 2000;Kaiser & Cai, 2012;Liu et al, 2022). Investigating the instability mechanism of rock structural planes under the conditions of stress disturbance is crucial for effectively preventing and reducing the incidence of engineering accidents.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on instability of rock structural planes induced by stress disturbances

Hu,

Liu,

et al. 2024

Preprint

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The activities in deep underground engineering may induce variations in the stress state of the rock, increasing the risk of engineering disasters. The decrease in normal stress σn and the increase in shear stress τs are considered as important causes for activation of rock structural planes to induce rockburst, earthquake and other disasters. In this study, numerical simulations are performed to reveal the influences of different stress paths on the dynamic slip mechanism of rock structural planes. The results show that the rock structural plane loaded to the near-critical failure state enters a slow slip state as the stress varies, and the frictional strength decreases with the exponentially increasing shear displacement ds, eventually resulting in dynamic slip. The displacement-driven mode overestimates the friction parameters µ by up to 14.5% compared with the stress-driven mode. The slow slip continuously weakens the ability of the structural plane to tolerate stress variation. The continuity and discontinuity of stress variation on structural plane affect the strengthening mode of µ. The stepwise stress path causes the stress on the structural plane to change dramatically, and may either cause the structural plane return to a slow-slip state or activate the structural plane to dynamic slip. Compared with the variation stress in σn, the variation stress in τs is more sensitive to triggering dynamic slip. The ds before dynamic slip is an important reference for evaluating the extent to tolerate stress variation. With increasing ds from 0.68 mm to 1.26 mm, the τs required to trigger dynamic slip decreases from 1.67 MPa to 1.49 MPa, suggesting that the ability of structural planes to tolerate stress variation is reduced.

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Section: Introductionmentioning

confidence: 99%

Numerical study on instability of rock structural planes induced by stress disturbances

Hu,

Liu,

et al. 2024

Preprint

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“…For low-frequency MS signals, most studies have investigated the practical engineering monitoring of large-scale rock masses. Liu et al (2022) highlighted that MS signals with low frequency before failure will appear with the investigation of MS signals underlying the failure of a coal-rock parting coal structure under biaxial compression. Sun et al (2021) found that MS event cluster characteristics based on the moment tensor inversion method can detect the occurrence of the rupture mode (dominated by tensile fractures) of a dome roof in a main transformer room.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the evolutionary characteristics of acoustic signals produced by granite under biaxial compression with different intermediate principal stresses

Lu,

Li,

Cai

2023

Front. Earth Sci.

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Biaxial compression is a typical stress state experienced by the surrounding rock near the excavation boundaries under deep underground engineering, frequently resulting in engineering geological disasters (spalling and rockburst). The motivation to mitigate the risk and damage of these disasters has led us to compressively examine the evolutionary characteristics of acoustic signals [microseismic (MS) events, sound and acoustic emission (AEs)] produced by granite under biaxial compression with different intermediate principal stresses. These characteristics include time (activeness and b value) and frequency (main frequency and proportion of the advantage frequency bands) domains. The results suggest that: 1) the signal properties-driven order of activeness under low and high intermediate principal stresses for the initial stresses were as follows: AE accounted for 37.4% and 43.5% of σpeak, MS for 61.1% and 66% of σpeak, and sound for 81.8% and 85.5% of σpeak. 2) The notable distinction in precursors of different acoustic signals before granite failure was confirmed: the sequential relationship in the continuous decrease rate of the b value (AE < MS < sound), the occurrence (only existing in AE signals) of a few signals with extremely high amplitude (the “quiescent period”) and the different frequency-change rule in the proportion of the advantage frequency bands. 3) The strong influences of intermediate principal stress on the signal precursors were determined; these precursors in the activeness, b value, and proportion are negative to intermediate principal stress, whereas that of the main frequency shows a positive correlation. Consequently, these findings can contribute integrated usage of the multifrequency signals in the prediction and warning of geological disasters under deep underground engineering.

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“…Through the direct shear test on the natural coal-rock interface specimen, the stress effect and lithologic effect of the coal rock combination specimen affected by the interface have been revealed [18]. The influence of rock in coal-rock samples on coal mechanical behavior has been established, and it has been determined that the greater the proportion of coal body, the lower the strength of the combination [19,20]. For roadways with coal-rock interface, most of the research focuses on the research and control of roadway deformation with an inclined interlayer structural plane, while there is less research on the constraint effect of horizontal coal-bearing rock interface on roadway instability.…”

Section: Introductionmentioning

confidence: 99%

Study on Deformation Characteristics of Surrounding Rock of Roadway with Coal–Rock Interface

2023

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Surrounding rock of roadway with a coal–rock interface is a common form in coal mines. In order to determine deformation characteristics and obtain the control principle of roadways with a coal–rock interface, the interface between the roof and coal seam was added to simulate the weak cohesion between the stratum. In this model, the interface shear stiffness was considered to be one of the key factors affecting horizontal inward movement of the roadway sidewalls. The deformation of the roadway with or without coal–rock interface under different burial depths was analyzed. Then, the shear stiffness of the interface element was changed to study the influence of shear stiffness on roadway deformation. At the same time, the characteristics of discontinuous deformation caused by the coal–rock interface at different positions in the roadway were studied. The results show that the roadway sidewall appeared to bulge in the middle and there is no dislocation and a small deformation in the contact position of the roadway sidewall with the roof and the floor when there is no interface between the stratum of the roadway. When there is an interface, the sidewall of the roadway is extruded as a whole, the slip and dislocation between the coal sidewall and the roof were obvious, and the maximum deformation of the sidewall is 1.68 times that of the roadway without an interface. When the shear stiffness of the interface is low, the deformation and the range of the plastic zone of roadway are large, with a large deformation at the upper part of the roadway sidewall, and a small deformation at the lower part of the roadway sidewall. The deformation of sidewall at the interface position decreases gradually with the increase of the interface shear stiffness, approaching the shape without the interface. When the coal–rock interface is at the sidewall of the roadway, the deformation of the rock and coal body at the interface is discontinuous, with slip and dislocation. The greater the proportion of rock height in the roadway sidewall, the greater the rock deformation. On the contrary, the coal deformation increases. It is more reasonable to simulate the deformation of roadways by adding a coal–rock interface, and the results are closer to the actual situation.

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Mechanisms Underlying the Slip and Failure of Coal-Rock Parting-Coal Structures Under Unloading Conditions

Cited by 5 publications

References 44 publications

Numerical study on instability of rock structural planes induced by stress disturbances

Numerical study on instability of rock structural planes induced by stress disturbances

Experimental study on the evolutionary characteristics of acoustic signals produced by granite under biaxial compression with different intermediate principal stresses

Study on Deformation Characteristics of Surrounding Rock of Roadway with Coal–Rock Interface

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