Damage evolution mechanisms of rock in deep tunnels induced by cut blasting

Xie, L.X.; Lu, Wenbo; Zhang, Qianbing; Jiang, Qinghui; Wang, Gaohui; Zhao, Jun

doi:10.1016/j.tust.2016.06.004

Cited by 207 publications

(73 citation statements)

References 24 publications

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“…In engineering practices, Kwon et al [13] pointed out in the blasting construction of deep-buried tunnel the importance of understanding and evaluating the influence of deep initial stress field on blasting excavation behavior. In the blasting excavation process of underground hydropower station, Lu et al [14,15] found that initial static stress field in deep rock mass had a remarkable influence on crack propagation in borehole-blasting construction and pointed out that the blasting design for deep rock mass in accordance with the blasting parameters of shallow rock mass was unreasonable. The aforementioned research phenomenologically analyzes the propagation behavior of blast-induced cracks in initial static stress field with a lack of theoretical analysis and quantitative research.…”

Section: State Of the Artmentioning

confidence: 99%

Experimental Study of the Dynamic Mechanical Behavior of Blast-Induced Cracks in Tensile Stress Field

Huang¹,

Ding²,

Xie³

et al. 2020

JESTR

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The propagation behavior of blasting-induced cracks directly determines rock fragmentation and blasting effect. None of existing engineering blasting parameter design has considered the influence of initial tensile stress field on the propagation behavior of blast-induced cracks with a lack of theoretical and experimental guidance; therefore, the rock blasting effect in tensile stress field is far from ideal. The stress distribution and crack stress state around borehole under the coupling action of static tensile stress and blasting stress were determined based on the theory of elastic mechanics to reveal the propagation behavior of blast-induced cracks in the initial tensile stress field and the blasting fracture mechanism. Caustic method and digital laser dynamic caustic experimental system were combined to investigate and analyze laws influencing initial tensile stress and pre-crack angle on dynamic mechanical behavior, such as propagation velocity and dynamic stress intensity factor of blast-induced cracks in the tensile stress field. Results show that under the initial tensile stress field, the stress state of borehole wall in the direction of the vertical stress field is mainly circumferential tensile stress. Blast-induced cracks can easily experience crack initiation in this direction to form better crushing effect. The tensile stress field exhibits an inhibitory effect on the propagation of blast-induced cracks parallel to the direction of tensile stress while having a facilitating effect on the propagation of blast-induced cracks perpendicular to the direction of tensile stress. As the tensile stress field is enlarged, the propagation velocity, dynamic stress intensity factor, and propagation length of blast-induced cracks perpendicular to the direction of tensile stress can also increase. Furthermore, the enlarging pre-crack angle in the tensile stress field can postpone the attenuation of dynamic stress intensity factor and propagation velocity of blast-induced cracks and enlarge their attenuation amplitudes. This study can provide a theoretical guidance for engineering blasting practice in tensile stress field.

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Section: State Of the Artmentioning

confidence: 99%

Experimental Study of the Dynamic Mechanical Behavior of Blast-Induced Cracks in Tensile Stress Field

Huang¹,

Ding²,

Xie³

et al. 2020

JESTR

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“…Generally, it is ideal to investigate the static problems using the implicit algorithm method in ANSYS, before solving the dynamic problem by the explicit algorithm method in LS-DYNA [30]. Moreover, the implicit-explicit analysis method, which combines the advantages of both the implicit and explicit algorithm methods, is included in LS-DYNA and can effectively deal with static-dynamic coupling calculation problems [31]. In the implicit analysis, the solid 185 is adopted as the element type, before the preloading is applied to the boundary condition of the rock model.…”

Section: Basic Theory Of Ls-dynamentioning

confidence: 99%

Analysis of Roadheader for Breaking Rock Containing Holes under Confining Pressures

Liu

Jiang

et al. 2017

Energies

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Deep underground mines have high energy consumption due to the need to overcome the confining pressure. This study investigates the characteristics of the roadheader used for breaking rock containing a different number and size of holes under different confining pressures. A series of simulations were conducted using the LS-DYNA software to study the cutting torque, thrust force, specific energy, and failure mode during the rock-breaking process. Following this, the results were further validated with experimental data. It was found that the decrease in energy rates of rock containing different numbers (1, 5, 9, and 13) of holes are 12.7%, 19.3%, 25.9%, and 38.4%, respectively. Meanwhile, the decrease in energy rates of rock with different hole diameters (35, 45, 55, and 65 mm) are 10.5%, 19.3%, 24.6%, and 28.1%, respectively. Under the confining pressure of 10 MPa, the increase in the torque of the rock without holes is 23.5%, while this increase in the rock with five holes is 7.9%. This indicates that the high torque and energy consumption caused by the confining pressure can be reduced by drilling holes in the rock.

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“…e rock fragmentation by blasting is the first stage of the comminution process in mine, and it affects every downstream operation, such as digging, hauling, crushing, and grinding; therefore, it is vital for the efficiency of deep mining operation [3,4]. When the rock mass is subjected to high in situ stress, the rock fragmentation by blasting is impeded by high in situ stress [4][5][6], and several issues, such as underbreak and oversize fragmentation, can be aroused. To response this situation, it is essential to study the rock fracturing by blasting with the aim of expected rock fragmentation when the rock mass is subjected to high in situ stress.…”

Section: Introductionmentioning

confidence: 99%

“…More excellent works on the numerical modelling of rock blasting can be found in reviews of Latham and Lisjak [35,36]. At present, many numerical studies [4][5][6][37][38][39][40][41] in investigating the fracturing mechanism of rock under blast loading and in situ stress have been performed. In 1997, Donze et al [41] developed a numerical model based on the discrete element method to investigate the effect of stress waves on the initiation and propagation of radial cracks in an uniaxial static stress field during the dynamic loading phase of an explosion.…”

Section: Introductionmentioning

confidence: 99%

Study of the Rock Crack Propagation Induced by Blasting with a Decoupled Charge under High In Situ Stress

Liu

Yang

2020

Advances in Civil Engineering

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The high in situ stress can significantly affect the blast-induced rock fragmentation and cause difficulties in deep mining and civil engineering where the drilling and blasting technique is applied. In this study, the rock crack propagation induced by blasting under in situ stress is first analyzed theoretically, and then a numerical model with a decoupled charge in LS-DYNA is developed to reveal how the initiation and propagation of rock cracks are under high in situ stress. Through simulation, the mechanisms of blast-induced crack evolution under various hydrostatic pressures and nonhydrostatic pressures are investigated, and the differences in crack evolution with specific decoupling coefficients are compared. According to the simulation, three damage zones, i.e., the crushed zone, the nonlinear fracture zone, and the radial crack propagation zone, are formed, and the radial crack evolution is greatly suppressed by the high in situ stress which has no much influence on the crack propagation in the crushed and the nonlinear fracture zones. The velocity of crack propagation is slightly reduced, and the process of crack propagation is stopped early when the rock is subjected to high in situ stress. Furthermore, the numerical analysis indicates that the crack grows preferentially in the direction of maximum principal stress, and the radial crack propagation is predominantly controlled by the preloaded pressure, which is vertical to the crack propagation direction. Based on the numerical results, it is suggested that the optimal decoupling coefficients for rock cracking are 2.65, 1.87, 1.37, and 1.22 for 0, 10, 20, and 30 MPa, respectively. This study provides not only an analysis of the rock crack evolution under high in situ stress but also a reference for resolving excavation difficulties in deep mining.

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Damage evolution mechanisms of rock in deep tunnels induced by cut blasting

Cited by 207 publications

References 24 publications

Experimental Study of the Dynamic Mechanical Behavior of Blast-Induced Cracks in Tensile Stress Field

Experimental Study of the Dynamic Mechanical Behavior of Blast-Induced Cracks in Tensile Stress Field

Analysis of Roadheader for Breaking Rock Containing Holes under Confining Pressures

Study of the Rock Crack Propagation Induced by Blasting with a Decoupled Charge under High In Situ Stress

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