Influence of delay time on the blasting effect of multiple charging forms in single free-face rock masses

Abstract

In order to improve excavation efficiency, we considered coal mine rock roadway blasting excavation as a background to examine the influence of delay time on the blasting effect of different charging structures under single free-surface conditions. Single-pore dispersed-charge models, dual-pore continuous-charge models, and dual-pore composite charge models were established. Their respective explosive rock-breaking mechanisms were explained using different models. These three numerical models were used to analyze the influence of delay time changes on the pressure and velocity of the measurement points near boreholes. The models were used to evaluate the blasting effects by determining the number of free-surface rocks. Engineering experiments were conducted to validate the numerical findings. The results showed that a single-hole dispersed charge creates a cavity and a new free surface, which increases the impact of deep-hole blasting compared to stress wave superposition. Dual-hole continuous-charge detonation is difficult, and short-delay detonation can effectively use stress wave superposition and prolong the action time of the explosive gas. The cavities created by the dispersed charges can be used to increase the efficiency of dual-hole composite charge blasting.

Keywords

underground mine blasting excavation / delay blasting / blasting cavity / dispersed charge / free surface

References

[1] Zhu XG, Ding CX, Sui Z, Su H, Guo X. Rock fracture mechanism of buffer blasting with cushion layer at the borehole bottom. Int. J. Miner. Metall. Mater., 2025, 32(2): 325

[2] Ainalis D, Kaufmann O, Tshibangu JP, Verlinden O, Kouroussis G. Modelling the source of blasting for the numerical simulation of blast-induced ground vibrations: A review. Rock Mech. Rock Eng., 2017, 50(1): 171

[3] You YY, Yang RS, Zuo JJ, et al. . Mechanism of iron ore blasting fracture using axial uncoupled charges. Int. J. Miner. Metall. Mater., 2025, 32(4): 788

[4] Wu XD, Gong M, Wu HJ, Hu GF, Wang SJ. Vibration reduction technology and the mechanisms of surrounding rock damage from blasting in neighborhood tunnels with small clearance. Int. J. Min. Sci. Technol., 2023, 33(5): 625

[5] Yang RS, Zuo JJ, Ma LW, Zhao Y, Liu Z, Xie QM. Analysis of explosion wave interactions and rock breaking effects during dual initiation. Int. J. Miner. Metall. Mater., 2024, 31(8): 1788

[6] C.X. Li, R.S. Yang, Y.B. Wang, Y.Q. Kang, and Y.T. Zhang, Theory and numerical simulation of deep hole cut blasting based on dispersed charge and staged detonation, Int. J. Rock Mech. Min. Sci., 169(2023), art. No. 105453.

[7] Vanbrant F, Espinosa A. Impact of short delays sequence on fragmentation by means of electronic detonators: Theoretical concepts and field validation. Fragblast, 2006, 8: 326

[8] Wu HJ, Gong M, Yang RS, Wu XD, Liu XY. Double-face intelligent hole position planning method for precision blasting in roadways using a computer-controlled drill jumbo. Int. J. Miner. Metall. Mater., 2023, 30(6): 1025

[9] Rossmanith HP. The use of Lagrange diagrams in precise initiation blasting. Part I: Two interacting blastholes. Fragblast, 2002, 6(1): 104

[10] Yue ZW, Guo Y, Wang X, Guo YL. Dynamic caustics study of influence of delayed initiation on crack propagation between boreholes. Chin. J. Rock Mech. Eng., 2015, 34(11): 2293

[11] McKinstry R, Floyd J, Bartley D. Electronic detonator performance evaluation. Proceedings of the 28th Annual Conference on Explosives and Blasting Technique, 2002: 1

[12] Khandelwal M, Singh TN. Prediction of blast-induced ground vibration using artificial neural network. Int. J. Rock Mech. Min. Sci., 2009, 46(7): 1214

[13] Johansson D, Ouchterlony F. Shock wave interactions in rock blasting: The use of short delays to improve fragmentation in model-scale. Rock Mech. Rock Eng., 2013, 46(1): 1

[14] C.X. Ding, R.S. Yang, and C. Feng, Stress wave superposition effect and crack initiation mechanism between two adjacent boreholes, Int. J. Rock Mech. Min. Sci., 138(2021), art. No. 104622.

[15] Blair DP. Limitations of electronic delays for the control of blast vibration and fragmentation. Proceedings of the 9th International Symposium on Rock Fragmentation by Blasting, 2010: 171

[16] Blair DP. Non-linear superposition models of blast vibration. Int. J. Rock Mech. Min. Sci., 2008, 45(2): 235

[17] X.D. Wu, M. Gong, H.J. Wu, and X.Y. Liu, Parameter calculation of the initiating circuit with mixed use of nonel detonators and electronic detonators in tunnel controlled-blasting, Tunn. Undergr. Space Technol., 113(2021), art. No. 103975.

[18] H. Zhang, T.C. Li, S. Wu, X.T. Zhang, W.L. Gao, and Q.P. Shi, A study of innovative cut blasting for rock roadway excavation based on numerical simulation and field tests, Tunn. Undergr. Space Technol., 119(2022), art. No. 104233.

[19] Silva J, Li LF, Gernand JM. Reliability analysis for mine blast performance based on delay type and firing time. Int. J. Min. Sci. Technol., 2018, 28(2): 195

[20] Hashemi AS, Katsabanis P. The effect of stress wave interaction and delay timing on blast-induced rock damage and fragmentation. Rock Mech. Rock Eng., 2020, 53(5): 2327

[21] Zhang ZR, Ding CX, Zuo JJ, et al. . Experiment study on rock breaking mechanisms of two-step cutting technology in rock roadways. Chin. J. Rock Mech. Eng., 2020, 39(1): 93

[22] Qiu XY, Shi XZ, Gou YG, Zhou J, Chen H, Huo XF. Short-delay blasting with single free surface: Results of experimental tests. Tunn. Undergr. Space Technol., 2018, 74: 119

[23] K. Hino, Fragmentation of rock through blasting and shock wave theory of blasting, [in] Proceedings of the 1st U.S. Symposium on Rock Mechanics (USRMS), Golden, 1956, art. No. ARMA-56-0191.

[24] Langefors U, Kihlstrom B. The Modern Technique of Rock Blasting, 1963, Stockholm, Almqvist & Wiksell

[25] Henrych J. The Dynamics of Explosion and Its Use, 1979, Amsterdam and New York, Elsevier Scientific Publishing Company

[26] Ding CX, Yang RS, Guo X, Sui Z, Xiao CL, Yang LY. Effects of the initiation position on the damage and fracture characteristics of linear-charge blasting in rock. Int. J. Miner. Metall. Mater., 2024, 31(3): 443

[27] Kutter HK, Fairhurst C. On the fracture process in blasting. Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 1971, 8(3): 181

[28] Xahykaeb AH. Physical Process of Blasting in Rock, 1980, Bejing, Metallurgical Industry Press: 123

[29] Liu XY, Gong M, Yang RS, et al. . Identification and application of the formation time of new free surface in tunnel blasting. J. Vib. Shock., 2023, 42(10): 15

[30] Lu WB, Yang JH, Yan P, et al. . Dynamic response of rock mass induced by the transient release of in situ stress. Int. J. Rock Mech. Min. Sci., 2012, 53: 129

[31] Gong M, Wu HJ. High-speed photography image acquisition system in tunnel blasting and parameters study on precisely controlled blasting. Explos. Shock. Waves, 2019, 39(5): 3

[32] L.B. Lucy, A numerical approach to the testing of the fission hypothesis, Astron. J., 82(1977), art. No. 1013.

[33] L.B. Jayasinghe, J.L. Shang, Z.Y. Zhao, and A.T.C. Goh, Numerical investigation into the blasting-induced damage characteristics of rocks considering the role of in situ stresses and discontinuity persistence, Comput. Geotech., 116(2019), art. No. 103207.

[34] H. Zhang, T.C. Li, Y.T. Du, Q.W. Zhu, and X.T. Zhang, Theoretical and numerical investigation of deep-hole cut blasting based on cavity cutting and fragment throwing, Tunn. Undergr. Space Technol., 111(2021), art. No. 103854.

[35] Z.L. Wang, H.C. Wang, J.G. Wang, and N.C. Tian, Finite element analyses of constitutive models performance in the simulation of blast-induced rock cracks, Comput. Geotech., 135(2021), art. No. 104172.

[36] Lia A, Souli M. High explosive simulation using multi-material formulations. Appl. Therm. Eng., 2006, 26(10): 1032

[37] Wang HB, Xu X, Zong Q, Xu SM, Xu Y. Research and application of hard rock deep-hole advance blasting in comprehensive roadway excavation. J. China Coal Soc., 2017, 42(4): 908

[38] Busch CL, Martin CTA, Tarefder RA. Experimental evaluation of cratering and ground vibration in clay soils subjected to explosive airblast loading. J. Test. Eval., 2015, 43(2): 414

[39] C.X. Li, R.S. Yang, Y.B. Wang, Y.Q. Kang, Y.T. Zhang, and P. Xie, Theoretical and numerical simulation investigation of deep hole dispersed charge cut blasting, Int. J. Coal Sci. Technol., 10(2023), No. 1, art. No. 15.

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