Energy regulation mechanism and medium-filling effect of energy-focusing blast

Abstract

The energy-focusing blast is an innovative and ingenious method to achieve directional fracturing. Understanding its energy regulation mechanism is critical to enhancing its practical effectiveness. This study investigates the energy regulation mechanism and explores the medium-filling effects within the energy-focusing blast by employing theoretical analysis, numerical simulations, and model tests. The findings by theoretical and numerical analysis first reveal that two stages of the fracturing and tensile stage govern the directionally crack propagation, in which the explosion energy in the non-energy-focusing direction is suppressed, compressing the borehole wall, while redirected energy produces tensile stress in the energy-focusing direction, driving the formation of directional cracks. The choice of filling medium significantly affects directional cracking due to its impact on energy distribution and regulation, and key properties such as wave impedance and compressibility of the filling medium are critical. Experimental comparisons using air, sand, and water as filling media further disclose the distinct effects of the medium on energy regulation and directional crack growth of the energy-focusing blast. The maximum shaped-energy coefficients for air, sand, and water are 1.30, 4.41, and 6.12 in the energy-focusing direction, respectively. Meanwhile, the stress attenuation rate of air, sand, and water increases in that order. The higher wave impedance and lower compressibility of water support efficient and uniform energy propagation, which subtly enhances the tensile actions in the focusing direction and intensifies the overall stress impact of the energy-focusing blast. In addition, the stresses in the non-energy-focusing directions decrease as the angle from the energy-focusing direction increases, while the stresses are relatively uniform for both air and water but noticeably uneven for sand; meanwhile, the fractal dimensions of blasting cracks in the case of air, water, and sand are 1.076, 1.068, and 1.112, respectively. Sand as a filling medium leads to increased crack irregularities due to its granularity and heterogeneity. The water medium strikes an optimal balance by promoting the blasting energy transition and optimizing the energy distribution, maintaining the least flatness of the directional crack during energy-focusing blasts.

Keywords

Directional blast / Medium influence / Energy utilization / Fracture mechanism

Acknowledgments

This work was supported by the National Natural Science Foun-dation of China (No. 51904188), the China Postdoctoral Science Foundation Funded Project (No. 2024M763564), and the Key Lab-oratory of Rock Mechanics and Geohazards of Zhejiang Province (No. ZJRMG-2022-03), which are gratefully acknowledged.

Supplementary material

Supplementary data to this article can be found online at https://doi.org/10.1016/j.ijmst.2025.03.010.

References

[1] Fu Q, Yang J, Gao YB, Li CJ, Song HX, Liu YX, Wu X. Combined blasting for protection of gob-side roadway with thick and hard roof. J Rock Mech Geotech Eng 2024; 16(8):3165-80.

[2] Guo PF, Liang HD, Zhang XY, Liu X, Jin ZP, Ye KK. A new method of cutting seam for preventing strain rock burst: Insights from experimental and numerical tests. Rock Mech Rock Eng 2024; 57(11):9923-39.

[3] Wu XG, Wang MY, Lu H, Zhang YJ, Nie W. Modified Sadowski formula-based model for the slope shape amplification effect under multistage slope blasting vibration. Int J Min Sci Technol 2024; 34(5):631-41.

[4] Doktan M, Tadic D. Blasthole slotting for controlled blast damage in open cut coal mines. In:Proceedings of the Australian Mining Technology Conference. Brisbane: CRCMining; 2005.p.255-65.

[5] Liu CW, Hu YZ, Zhang P, Deng ED, Huang YQ, Nie ZQ, Zhang X. Experimental study on directional fracturing by slotted hydraulic blasting in underground drilling. Nat Gas Ind B 2024; 11(4):454-67.

[6] Zhang ZF, Wang LK, Silberschmidt VV. Damage response of steel plate to underwater explosion: Effect of shaped charge liner. Int J Impact Eng 2017; 103:38-49.

[7] Mehmannavaz H, Ramezani A, Nabakhteh MA, Liaghat G. A practical review study on shaped charge in the last two decades (2000-2020). Int J Prot Struct 2021; 12(4):665-93.

[8] Ding CX, Yang RS, Xiao CL, Chen JH, Wang DS, Gong M, Feng C. Directional fracture behavior and stress evolution process of the multi-slit charge blasting. Soil Dyn Earthq Eng 2022; 152:107037.

[9] Xiao CL, Yang RS, Zhao ZW, You S, He SL, Zhang YT. Blasting damage control of slit charge structure. Mech Adv Mater Struct 2024; 31(25):6848-62.

[10] Zhang Q, He MC, Wang J, Guo S, Guo ZB, Liu XY, Hu JZ, Ma ZM, Fan LX, Guo PF. Instantaneous expansion with a single fracture: A new directional rock-breaking technology for roof cutting. Int J Rock Mech Min Sci 2020; 132:104399.

[11] Zhang XY, Hu JZ, Xue HJ, Mao WB, Gao YB, Yang J, He MC. Innovative approach based on roof cutting by energy-gathering blasting for protecting roadways in coal mines. Tunn Undergr Space Technol 2020; 99:103387.

[12] Li XL, Yan SQ, Wang JG, Li Q. Influence of slot width in cartridge on crack propagation and energy concentration under explosion load. Rock Mech Rock Eng 2025; 58(2):1707-21.

[13] Zhang Z, Jin WW. Finite element modeling of the shaped charge jet and design of the reusable perforating gun. Petrol Sci 2020; 17(5):1389-99.

[14] Yang RS, Ding CX, Li YL, Yang LY, Zhao Y. Crack propagation behavior in slit charge blasting under high static stress conditions. Int J Rock Mech Min Sci 2019; 119:117-23.

[15] Yang LY, Huang C, Bao SJ, Zhang LY. Model experimental study on controlled blasting of slit charge in deep rock mass. Soil Dyn Earthq Eng 2020; 138:106318.

[16] He MC, Zhang XH, Zhao S. Directional destress with tension blasting in coal mines. In: Proceedings of the ISRM International Symposium-EUROCK 2017. Ostrava: CRC Press; 2017.p.89-97.

[17] He MC, Cao WF, Shan RL, Wang S. New blasting technology-bilateral cumulative tensile explosion. Chin J Rock Mech Eng 2003; 22(12):2047-51. in Chinese.

[18] Zhang XY, Pak RYS, Yang J, Lei L, Niu HY, Niu YS, Zhao CW, Gao HN, He MC. Mechanistic formulation and validation of cutting seam by energy-focusing blast for pressure relief of deep roadway. Eng Fail Anal 2023; 150: 107378.

[19] Zhang XY, He MC, Yang J, Wang EY, Zhang JB, Sun Y. An innovative non-pillar coal-mining technology with automatically formed entry: A case study. Engineering 2020; 6(11):1315-29.

[20] Zhang XY, Yang J, Gao YB, Xue HJ, Guo PF, He MC. Pressure-relief technique and its application based on seam-cutting compensation in high-stress roadway. J China Coal Soc 2024; 49(11):4377-89. in Chinese.

[21] Hou SL, Wang YJ, Yang J, Zhang J, He MC, Li HC, Yang G, Chen GH. A new model test method for single-fracture oriented roof-cutting technology. Min Metall Explor 2024; 41(5):2539-54.

[22] Zhang Q, Tao ZG, Yang C, Guo S, He MC, Zhang CY, Niu HY, Wang C, Wang S. Experimental and numerical investigation into the non-explosive excavation of tunnels. J Rock Mech Geotech Eng 2022; 14(6):1885-900.

[23] Guo S, Jeon S, Zhang Q, He MC, Liu JN, Wang C, Sui Q. Investigation on directional rock fracture mechanism under instantaneous expansion from the perspective of damage mechanics: A 3-D simulation. Simul Model Pract Theory 2024; 137:103013.

[24] Hu JZ, Zhang XY, Gao YB, Ma ZM, Xu XZ, Zhang XP. Directional presplit blasting in an innovative no-pillar mining approach. J Geophys Eng 2019; 16 (5):875-93.

[25] Zhang XY, Pak RYS, Gao YB, Liu CK, Zhang C, Yang J, He MC. Field experiment on directional roof presplitting for pressure relief of retained roadways. Int J Rock Mech Min Sci 2020; 134:104436.

[26] Gao YB, Wang YJ, Yang J, Zhang XY, He MC. Meso- and macroeffects of roof split blasting on the stability of gateroad surroundings in an innovative nonpillar mining method. Tunn Undergr Space Technol 2019; 90:99-118.

[27] Zuo JJ, Yang RS, Gong M, Ge FY. Effect of different filling media between explosive and blast-hole wall on rock blasting. Rock Mech Rock Eng 2023; 56 (8):5705-17.

[28] Chéret R.Chapman-Jouguet hypothesis 1899-1999: One century between myth and reality. Shock Waves 1999; 9(5):295-9.

[29] Zhang ZG, Qiu XY, Shi XZ, Luo ZH, Chen H, Zong CX. Burden effects on rock fragmentation and damage, and stress wave attenuation in cut blasting of large-diameter long-hole stopes. Rock Mech Rock Eng 2023; 56(12): 8657-75.

[30] Zhang ZX. Rock Fracture and Blasting: Theory and Applications. Oxford: Butterworth-Heinemann; 2016.

[31] Fasanella EL, Jackson KE, Sparks CE, Sareen AK. Water impact test and simulation of a composite energy absorbing fuselage section. J Am Helicopter Soc 2005; 50(2):150-64.

[32] Rigby SE, Akintaro OI, Fuller BJ, Tyas A, Curry RJ, Langdon GS, Pope DJ. Predicting the response of plates subjected to near-field explosions using an energy equivalent impulse. Int J Impact Eng 2019; 128:24-36.

[33] Kumar S, Saxena S, Sharma H, Gangolu J, Prabhu TA. Development of design guidelines using probabilistic framework for the development of smart thickening fluid based ultra resistant adaptive kinematic soft human armor (SURAKSHA). Reliab Eng Syst Saf 2023; 236:109277.

[34] Wang XF, Hu SB, Wang EY, Zhang Q, Liu B. Experimental research and energy analysis of a new type of dry ice powder pneumatic rock breaking technology. Int J Min Sci Technol 2023; 33(4):423-35.

[35] Yang LY, Yang AY, Chen SY, Fang SZ, Huang C, Xie HZ. Model experimental study on the effects of in situ stresses on pre-splitting blasting damage and strain development. Int J Rock Mech Min Sci 2021; 138:104587.

[36] Guo PF, Zhao YX, Zhang XY, Deng SW, Zhang XY, Zhang HJ, Li ZK, He MC. Spatial size effect study of broken-expansion mass using rock-like materials under the 110/N00 mining method. Geomech Eng 2024; 39:441-53.

[37] Fookes PG, Walker MJ. Concrete: A man-made rock? Geol Today 2010; 26 (2):65-71.

[38] Thompson AH. Fractals in rock physics. Annu Rev Earth Planet Sci 1991; 19:237-62.

[39] Xie HP. Fractals in Rock Mechanics. London: CRC Press; 2020.

[40] Ristin M, Guillaumin M, Gall J, Van Gool L. Incremental learning of random forests for large-scale image classification. IEEE Trans Pattern Anal Mach Intell 2016; 38(3):490-503.

[41] Shanmugam P, Raja J, Pitchai R. An automatic recognition of glaucoma in fundus images using deep learning and random forest classifier. Appl Soft Comput 2021; 109:107512.

[42] Lovejoy S, Schertzer D, Tsonis AA. Functional box-counting and multiple elliptical dimensions in rain. Science 1987; 235(4792):1036-8.

[43] Bagde MN, Raina AK, Chakraborty AK, Jethwa JL. Rock mass characterization by fractal dimension. Eng Geol 2002; 63(1-2):141-55.