Experimental study on artificially induced crack patterns and their consequences on mechanical excavation processes

Hartlieb, Philipp; Grafe, Bruno; Shepel, Taras; Malovyk, Artem; Akbari, Behnam

doi:10.1016/j.ijrmms.2017.10.024

Cited by 62 publications

(15 citation statements)

References 15 publications

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“…12 is a scatter plot of the specific energy consumption calculated by Eq. 6 4 Experimental study A large number of rock cutting experiments have been done at home and abroad [2,[23][24][25][26][27].The experiments were conducted on the Coal-rock Cutting Machine (CCM) in Central South University. As shown in Fig.…”

Section: Se W V Ttnmentioning

confidence: 99%

Establishment of Coal-rock Constitutive Models for Numerical Simulation of Coal-rock Cutting by Conical Picks

Qiao

Xia

et al. 2019

Period. Polytech. Civil Eng.

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One of the key points in numerical simulation of coal-rock cutting by conical picks is to select a proper coal-rock constitutive model. In order to find a reasonable coal-rock constitutive model, a uniaxial compression test was conducted to obtain the constitutive model. The several stages for linear elastic deformation and creep, plastic yielding, hardening, and finally brittle cracking of the constitutive units were studied, and the coal-rock constitutive model was established. As a result, the coal-rock cutting by one conical pick or two conical picks was simulated and the results were compared with coal-rock cutting experiment on a Coal-rock Cutting Machine. According to the simulation and experimental results, it is believed that the numerical simulation can reveal coal-rock crushing process. And the total error rate of coal-rock cutting by one conical pick between the simulation and experiment is 8.5%. The maximum deviation of coal-rock cutting by two conical picks between the simulation and experiment is 9.8%. All simulation values are within a reasonable range. The comparison indicates that the coal-rock constitutive model should better be defined considering the coal-rock crushing process by conical picks.

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Section: Se W V Ttnmentioning

confidence: 99%

Establishment of Coal-rock Constitutive Models for Numerical Simulation of Coal-rock Cutting by Conical Picks

Qiao

Xia

et al. 2019

Period. Polytech. Civil Eng.

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“…Furthermore, an increase in the unloading failure strength can be observed for the preflawed specimen with the increase in the flaw inclination angle. In order to better understand the influence of preflaws on the strength properties of rock specimens under unloading condition, quantitative investigations on 8 Geofluids the unloading failure strength were carried out. Figure 9 presented the correlation between the unloading failure strength and flaw inclination angle.…”

Section: Geofluidsmentioning

confidence: 99%

“…Therefore, the underground mining may lead to sudden and severe rock mass failure, posing a significant threat to the safety and stability of underground structures [5][6][7]. In this regard, the mechanical excavation method with controllable energy release is considered to be superior to the drill-and-blast method in the operations of underground excavation such as mining and tunneling [8]. Nowadays, mining equipment manufacturers are developing new machine concepts with the aim of using a mechanical excavation method in underground mining and tunneling operations [9].…”

Section: Introductionmentioning

confidence: 99%

Influence of Flaw Inclination Angle on Unloading Responses of Brittle Rock in Deep Underground

Chen

Weng

et al. 2019

Geofluids

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Excavation unloading is a primary stress condition for engineering rock mass in deep underground. Based on the unloading stress condition during the excavation operation, this paper employed a distinct element method (DEM) to simulate the unloading responses of intact and preflawed rock specimens. The simulation results revealed that the unloading failure strength, unloading damage thresholds, and cracking characteristics were largely dependent on the inclination angle α of the preflaws. With the increase in the flaw inclination angle, the unloading failure strength of a preflawed specimen exhibited a sigmoidal curve increasing trend, and it decreased by 5.5%-20% compared to the unloading failure strength of an intact specimen. Based on the crack accumulation in specimens, three damage thresholds were identified under unloading condition and two damage thresholds σci and σdi were found to be increased with the increase in the flaw inclination angle. Furthermore, when the flaw inclination angle was smaller, cracks were initiated around the preflaws, and there were obvious axial splitting cracks in the failure modes of preflawed specimens, while axial splitting cracks were few in the preflawed specimen with a larger flaw inclination angle and none in the intact specimen. These unloading responses indicate that inducing preflaws can reliably reduce the unloading failure strength and promote the cracking process of hard rock during an excavation unloading process. Moreover, inducing preflaws with a smaller inclination angle (e.g., vertical to the unloading direction) will be more helpful for the unloading failure and rock cracking during an excavation unloading process.

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“…Some scholars explored the mechanisms that controlled the development of mining-induced ground fissures in the context of various theories, including rock failure theory, surface deformation theory, and slope slip mechanisms. They established a mechanical model that described the formation of mining-induced ground fissures, and found that fractures in rocks and soil caused by underground mining were fundamental to the formation of ground fissures (Hartlieb et al, 2017;Zhu et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Factors that trigger the development of mining-induced ground fissures, and standards to treat them in shallow coal mining areas

Liu

Zhou

Liu

et al. 2019

J. S. Afr. Inst. Min. Metall.

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The exploitation of shallow coal seams causes severe surface subsidence and triggers the development of numerous ground fissures, which threaten the safety of underground mining and damage the surface eco-environment. We studied the law of surface movement and the development of ground fissures at three panels in the Daliuta coal mine, Shendong mining district of western China. The results showed that mining-induced ground fissures developed in a cycle of 'crack-expand-close', and formed permanent cracks that were arranged in an elliptical shape on the edge of the goaf. There was a positive linear relationship between the fissure width and the surface horizontal deformation, as one would expect, and a positive logarithmic relationship between the fissure angle and the mining rate during coal face advancing. We propose a basis and standard for treating dynamic fissures which recommends that, to ensure the safety of underground mining, the fissures should be treated when the surface cracks extend as far as the fractured zone of rock strata. The results will support predictions of the development of mining-induced ground fissures so that disasters can be prevented in shallow coal seam mining areas.

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Experimental study on artificially induced crack patterns and their consequences on mechanical excavation processes

Cited by 62 publications

References 15 publications

Establishment of Coal-rock Constitutive Models for Numerical Simulation of Coal-rock Cutting by Conical Picks

Establishment of Coal-rock Constitutive Models for Numerical Simulation of Coal-rock Cutting by Conical Picks

Influence of Flaw Inclination Angle on Unloading Responses of Brittle Rock in Deep Underground

Factors that trigger the development of mining-induced ground fissures, and standards to treat them in shallow coal mining areas

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