Effect of in-situ stresses on fracturing performance of crater blasting under different resistance lines

Abstract

In deep underground mining, high-stress condition plays a key role in rock blasting. However, the mechanism of rock breaking by blasting under high-stress conditions is still unclear. Therefore, crater blasting experiments and theoretical analyses were conducted to study the effect of in-situ stresses on rock fracturing. A 3D theoretical model considering stress concentration on the blasthole wall was conducted to further investigate the fracturing mechanism of crater blasting under in-situ stresses. The experimental and theoretical results allowed the following conclusions: 1) Long resistance line (over 6 cm) results in a decrease crater volume along with increasing confining pressure; 2) the influence of confining pressure on blasting gradually changes from negative restraining to positive promoting with decreasing resistance line (less than 5 cm); 3) Radial fracturing was restrained and the reflected tensile fracturing was promoted in the direction of higher in-situ stress. While, radial fracturing was promoted and the reflected tensile fracturing was restrained in the direction of lower in-situ stress. Reducing resistance line of crater blasting and increasing between spacing hole are the best to take advantage of the in-situ stress to promote the rock fragmentation by blasting.

Keywords

crater blasting / in-situ stresses / fracturing by blasting / resistance line

References

[1] ChenD, WangE, LiN. Study on the source parameters of the micro-earthquakes in Laohutai coal mine based on double difference relocation [J]. Soil Dynamics and Earthquake Engineering, 2021, 142: 106540

[2] RahimiB, SharifzadehM, FengX. Ground behaviour analysis, support system design and construction strategies in deep hard rock mining - Justified in Western Australian’s mines [J]. Journal of Rock Mechanics and Geotechnical Engineering, 2020, 12(1): 1-20

[3] Lippmann-PipkeJ, ErzingerJ, ZimmerM, et al. . Geogas transport in fractured hard rock - Correlations with mining seismicity at 3.54km depth, TauTona gold mine, South Africa [J]. Applied Geochemistry, 2011, 26(12): 2134-2146

[4] CaiM, ChampaigneD, CoulombeJ G, et al. . Development of two new rockbolts for safe and rapid tunneling in burst-prone ground [J]. Tunnelling and Underground Space Technology, 2019, 91103010

[5] HeC, YangJ. Dynamic crack propagation of granite subjected to biaxial confining pressure and blast loading [J]. Latin American Journal of Solids and Structures, 2018, 15(6): e45

[6] YangL, HuangC, BaoS, et al. . Model experimental study on controlled blasting of slit charge in deep rock mass [J]. Soil Dynamics and Earthquake Engineering, 2020, 138106318

[7] TaoJ, YangX, LiH, et al. . Effects of in-situ stresses on dynamic rock responses under blast loading [J]. Mechanics of Materials, 2020, 145103374

[8] DonzéF V, BouchezJ, MagnierS A. Modeling fractures in rock blasting [J]. International Journal of Rock Mechanics and Mining Sciences, 1997, 3481153-1163

[9] XieL X, LuW B, ZhangQ B, et al. . Analysis of damage mechanisms and optimization of cut blasting design under high in situ stresses [J]. Tunnelling and Underground Space Technology, 2017, 6619-33

[10] DaiJ, YangJ, YaoC, et al. . Study on the mechanism of displacement mutation for jointed rock slopes during blasting excavation [J]. International Journal of Rock Mechanics and Mining Sciences, 2022, 150: 105032

[11] ZhangS, QiuX, ShiX, et al. . Influence of detonator delay scatter on rock fragmentation by bunch-holes blasting [J]. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2022, 8(5): 136

[12] ShiX, QiuX, ZhouJ, et al. . Application of Hilbert-Huang transform based delay time identification in optimization of short millisecond blasting [J]. Transactions of Nonferrous Metals Society of China, 2016, 2671965-1974

[13] LiuK, LiX, HaoH, et al. . Study on the raising technique using one blast based on the combination of long-hole presplitting and vertical crater retreat multiple-deck shots [J]. International Journal of Rock Mechanics and Mining Sciences, 2019, 11341-58

[14] QiuX, ShiX, GouY, et al. . Short-delay blasting with single free surface: Results of experimental tests [J]. Tunnelling and Underground Space Technology, 2018, 74: 119-130

[15] YangL, DingC. Fracture mechanism due to blast-imposed loading under high static stress conditions [J]. International Journal of Rock Mechanics and Mining Sciences, 2018, 107: 150-158

[16] LuoS, YanP, LuW, et al. . Effects of In-situ stress on blasting damage during deep tunnel excavation [J]. Arabian Journal for Science and Engineering, 2021, 46(11): 11447-11458

[17] ZhangF, YanG, PengJ, et al. . Experimental study on crack formation in sandstone during crater blasting under high geological stress [J]. Bulletin of Engineering Geology and the Environment, 2020, 79(3): 1323-1332

[18] KutterH K, FairhurstC. On the fracture process in blasting [J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1971, 8(3): 181-202

[19] HoekE, BrownE TUnderground excavations in rock [M], 1980, London, Institution of Mining and Metallurgy

[20] MaG W, AnX M. Numerical simulation of blasting-induced rock fractures [J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(6): 966-975

[21] YilmazO, UnluT. Three dimensional numerical rock damage analysis under blasting load [J]. Tunnelling and Underground Space Technology, 2013, 38: 266-278

[22] YiC, JohanssonD, GrebergJ. Effects of in situ stresses on the fracturing of rock by blasting [J]. Computers and Geotechnics, 2018, 104: 321-330

[23] XiaoS, SuL, JiangY, et al. . Numerical analysis of hard rock blasting unloading effects in high in situ stress fields [J]. Bulletin of Engineering Geology and the Environment, 2019, 78(2): 867-875

[24] XuH, YangX, ZhangJ, et al. . A closed-form solution to spherical wave propagation in triaxial stress fields [J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 128: 104266

[25] ZhangF, PengJ, QiuZ, et al. . Rock-like brittle material fragmentation under coupled static stress and spherical charge explosion [J]. Engineering Geology, 2017, 220266-273

[26] PengJ, ZhangF, DuC, et al. . Effects of confining pressure on crater blasting in rock-like materials under electric explosion load [J]. International Journal of Impact Engineering, 2020, 139: 103534

[27] XieL X, LuW B, ZhangQ B, et al. . Damage evolution mechanisms of rock in deep tunnels induced by cut blasting [J]. Tunnelling and Underground Space Technology, 2016, 58257-270

[28] HanH, FukudaD, LiuH, et al. . Combined finite-discrete element modelling of rock fracture and fragmentation induced by contour blasting during tunnelling with high horizontal in situ stress [J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 127: 104214

[29] LiuF, GuoZ, LvH, et al. . Test and analysis of blast wave in mortar test block [J]. International Journal of Rock Mechanics and Mining Sciences, 2018, 10880-85

[30] OliveiraP J V, CorreiaA A S, TelesJ M N P C, et al. . Effect of cyclic loading on the behaviour of a chemically stabilised soft soil reinforced with steel fibres [J]. Soil Dynamics and Earthquake Engineering, 2017, 92: 122-125

[31] QianQ. Break blasting parameters for driving a roadway in rock with high residual stress [J]. Explosion and Shock Waves, 2007, 27(3): 272-277

[32] HenrychJDynamics of explosion and its use [M], 1979, Amsterdam, Elsevier Scientific Pub. Co.

[33] WangZ, LiY, ShenR F. Numerical simulation of tensile damage and blast crater in brittle rock due to underground explosion [J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(5): 730-738