Modelling of primary fragmentation in block caving mines using a finite-element based fracture mechanics approach

Paluszny, Adriana; Zimmerman, Robert W.

doi:10.1007/s40948-016-0048-9

Cited by 17 publications

(2 citation statements)

References 17 publications

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“…To eliminate the potential dangers, blasting method is utilized to loosen hard rocks. The forced roof caving technique based on directional rupture control blasting is proposed in engineering production to reduce the number of blastholes and blasting workload, improve the production efficiency, and lower the construction cost [19,20]. Under specific circumstances, excavation and unloading result in stress redistribution, which generates tensile stress in the rock mass or civil architecture and achieves the directional blasting effect through notched blasting.…”

Section: State Of the Artmentioning

confidence: 99%

Experimental Study on Notched Directional Blasting in Tensile Stress Field

Xie¹,

Huang²,

Zhang³

et al. 2020

JESTR

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Notched blasting has been extensively applied as a traditional directional blasting method. At present, the measurement of notched blasting effect and rock fragmentation is mainly decided by the propagation behavior of blast-induced cracks. However, the influence of initial tensile stress field on such behavior is rarely considered in existing engineering blasting process, resulting in the non-remarkable directional fracture effect of tensile rock mass. To reveal the propagation behavior of the propagation behavior of blast-induced cracks in the initial tensile stress field, as well as the fracture failure mechanism, the stress distribution state and propagation mechanism of the blast-induced cracks near the notched hole under the combined action of initial tensile stress and blasting stress were determined on the basis of the theory of elastic and fracture mechanics. The combined dynamic-static loading device and digital laser caustic experimental system were used to conduct the planar model failure experiment under the joint action of the initial tensile and blasting stress. The influence laws of the initial tensile stress and notch angle on the propagation length and velocity of the blastinduced main cracks, as well as the stress intensity factor at the crack tip, were also investigated through the experiment. The results showed that, (1) In the initial tensile stress field, as circumferential tensile stress was generated at the blasthole wall by initial tensile stress, the blast-induced main crack could be more easily propagate in the direction perpendicular to the initial tensile stress. (2) When the angle between the notch and the initial tensile stress was 45°, the initial tensile stress enlarged the propagation length of the main crack, and the propagation mode transitioned from Mode I to I-II mixed mode. In the meantime, the main crack deflected perpendicular to the initial tensile stress. (3) When the notch was parallel to the initial tensile stress, the main crack demonstrated a linear propagation along the direction of initial tensile stress. The initial tensile stress promoted the generation of the secondary cracks in the two sides of the blasthole and shortened the propagation length of the main crack, thereby reducing the stress intensity factor of the main crack. Results can serve as a reference for directional blasting in the initial static tensile stress field.

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Section: State Of the Artmentioning

confidence: 99%

Experimental Study on Notched Directional Blasting in Tensile Stress Field

Xie¹,

Huang²,

Zhang³

et al. 2020

JESTR

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“…Cao et al [19] simulated the ground settlement process caused by mining activity by the universal distinct-element code (UDEC). Paluszny and Zimmerman [20] simulated the growth of fractures around an undercut during caving by a finite-element-based method. Rafiee et al [21] studied the influence parameters on the cavability of rock mass in block caving mines by using PFC3D software.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis for the Caving Characteristics of Rock Mass with Inclined Joints in Caving Mining

Sui

Ren

Cao

et al. 2021

Advances in Civil Engineering

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In caving mining, the successful initiation and propagation of caving require one low-dip joint set. However, not every mine has a low-dip joint set. The Hemushan Iron Mine in China was taken as the engineering background, and the caving characteristics of rock mass with inclined joints were analyzed based on the synthetic rock mass (SRM) model. First, the inclined joints were investigated in the Hemushan Iron Mine. Second, model parameters were determined based on the geological conditions of the mine, and seven models were established. Third, the caving process was simulated, and caving characteristics were monitored. For rock mass with inclined joints after undercutting, the research showed that the crack zone was significant, and the crack zone existed not only around the undercut area but also further away in the model. The stress concentration areas dispersed in the model except for the top of the undercut area. The caving line was not a standard arch, and the highest point of the caving line was biased towards the direction of the undercut. Under the same undercut width, with the decrease of joint length in the joint system, the number of cracks decreased, the degree of stress concentration became weaker, and the height of the caving line decreased.

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