Comparison of Presplit and Smooth Blasting Methods for Excavation of Rock Wells

Zhou, Zilong; Cheng, Ruishan; Cai, Xun; Jia, Jinlong

doi:10.1155/2019/3743028

Cited by 19 publications

(14 citation statements)

References 30 publications

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“…By monitoring the model casting units, we found that the maximum casting velocity appeared at the middle of the blast-hole pack, with a velocity of 21.6 m/s. Additionally, this value is consistent with the conclusion regarding the maximum casting velocity proposed by Huang et al [36,37], which is 18-28 m/s. e average scattering distance is approximately 47 m, the postcracking distance is approximately 1.2 m, and the casting rate is approximately 34%.…”

Section: Casting State Of Motionsupporting

confidence: 93%

A Novel Method to Evaluate the Effect of Slope Blasting under Impact Loading

Zhou

et al. 2020

Shock and Vibration

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In this paper, the quantitative evaluation of the explosion effect based on the fuzzy comprehensive evaluation method is proposed to describe the qualitative evaluation results. The selected state characteristic parameters are expressed by two kinds of membership functions, fuzzy normal and triangular distribution membership functions, and preliminary evaluation results are obtained. The validity index of the maximum membership principle is used to assess the accuracy of the evaluation results of two algorithms, and a relevant approaching degree is chosen to optimize the results. The entire evaluation process selects eleven indicators to form an evaluation set, including the boulder yield, root rate, flying distance of flyrock, explosive consumption, postcracking distance, detonator unit consumption, vibration velocity, loose coefficient, cast distance, throw rate, and blasted volume per meter of hole. Part of the indicator parameters are derived from field test monitoring, and another part of the indicator parameters are derived from numerical simulation. The simulation process uses the user-defined material interface function provided by LS-DYNA. And the numerical model of slope blasting is established by embedding the evolution relationship of tensile and compressive damage into the elastoplastic constitutive material. The evaluation method proposed in this paper is used to evaluate the postexplosion effect of Zijin Mountain gold-copper mine slope cast blasting. The results demonstrate that the fuzzy normal distribution membership function can correlate the state characteristic information and evaluation index effectively, and the working condition after explosion can be reflected accurately. Additionally, the influencing factors can be ranked by the importance degrees according to the calculated value of the evaluation index.

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Section: Casting State Of Motionsupporting

confidence: 93%

A Novel Method to Evaluate the Effect of Slope Blasting under Impact Loading

Zhou

et al. 2020

Shock and Vibration

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“…Furthermore, the boreholes were fully charged [4][5][6], and this is not always in line with the practices of deep rock blasting. In fact, in deep mining, the charging in a number of boreholes is decoupled, especially in presplit blasting, smooth blasting, buffer blasting, and some production blasting [42][43][44], but few papers can be found to study the rock fracturing in blasting with a decoupled charge under high in situ stress.…”

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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“…Aforementioned studies of permeability evolution of fractured rock are limited in the quasistatic condition. Actually, rocks or rock masses are usually subject to cyclic disturbances, which probably come from earthquake, mining, and tunneling [25][26][27][28][29][30][31][32][33][34]. A large amount of studies suggested that cyclic loading can lead to severe fatigue damage or failure of rock even when the stress level is significantly lower than the static strength [35][36][37][38][39][40][41][42][43][44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Permeability Evolution of Fractured Rock Subjected to Cyclic Axial Load Conditions

et al. 2020

Self Cite

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Permeability experiments on saw-cut fractured rock subjected to cyclic axial load conditions were conducted on the MTS815 rock mechanics testing system. The influence of the frequency and amplitude of cyclic axial forces on axial displacement and permeability evolution of fractured rock was experimentally investigated. Results show that the increasing frequency under the same amplitude of axial load leads to a reduction in axial displacement, but a drop followed by an increase in permeability, while the permeability values oscillated sharply under high amplitude of cyclic loads, which can be attributed to the production of gouge materials. Besides, the increase in axial displacement roughly contributed to the permeability reduction, and excessive amplitude of cyclic load posed limited boost to the permeability enhancement. By comparing with the quasistatic function, we found that it did not completely correspond to the trend of the permeability evolution subjected to cyclic axial forces, and sensitivity coefficients evolving with frequency and amplitude should be considered. A new function of the permeability evolution subjected to the amplitude and frequency of cyclic axial forces was derived and verified by the experimental data. This study suggests that small amplitude and high frequency of dynamic forces have the potential for enhancing the permeability of fracture and triggering the disaster of fractured rock.

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Comparison of Presplit and Smooth Blasting Methods for Excavation of Rock Wells

Cited by 19 publications

References 30 publications

A Novel Method to Evaluate the Effect of Slope Blasting under Impact Loading

A Novel Method to Evaluate the Effect of Slope Blasting under Impact Loading

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

Permeability Evolution of Fractured Rock Subjected to Cyclic Axial Load Conditions

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