Cutting blasting is a crucial step in underground blasting driving. To investigate the influences of cutting cavity depth on subsequent rock breaking properties, driving sections with different cutting cavities depths were simplified as sandstone specimens with different depths of cavities. A series of dynamic compression tests were conducted using a 50 mm diameter split Hopkinson pressure bar (SHPB) testing system. Then, the dynamic peak stresses, dynamic peak strains, energy dissipation characteristics, and fracture patterns of the specimens were analyzed as the cavity depth varied, and the field cutting blasting parameters were optimized accordingly. The results demonstrate significant trends for sandstone specimens with cavity diameters of 10 and 20 mm. As the cavity depth increases, the dynamic peak stress decreases by 17.69% and 39.05%, the dynamic peak strain increases by 7.58% and 18.56%, the dissipation energy increases by 22.87% and 45.92%, the dissipation energy density increases by 26.92% and 73.08%, respectively. And the specimens fragmentation size also gradually decreases with the extension of cavity depth. These findings indicate that increasing cutting cavity depth could reduce the rock mass resistance to failure, enhance its deformation capacity and energy utilization efficiency, and improve its fragmentation effects. When the cavity diameter is 20 mm, the dynamic mechanical properties and energy dissipation characteristics of the specimens change at a faster rate with the increase of cavity depth, and the fragmentation size is smaller. This indicates that increasing the cutting cavity diameter is also beneficial for rock breaking. The cutting blasting technique with inner-hole and outer-hole composite delays is adopted, which can increase the cavity depth and diameter to provide sufficient free surfaces for subsequent blasting process. This optimization achieved remarkable filed performance that increasing the cycle advance and hole utilization rate of the full-section blasting into 5.0 m and 96.1%, and ensuring uniform and reasonable rock fragmentation degree. The research findings not only effectively reveal the influences of cutting cavity depth on the full-section rock breaking effects, but also provide theoretical supports and practical references for the design optimization of actual cutting blasting projects.

Accurate assessment of the residual bearing capacity of reinforced concrete (RC) columns is critical for ensuring structural safety in blasting demolition. However, existing models fail to account for the initial deflection of exposed longitudinal reinforcement, resulting in substantial discrepancies between theoretical predictions and experimental observations. To address this limitation, an improved strength reduction of longitudinal reinforcement (ISRLR) model was proposed. By incorporating the initial deflection factor of the reinforcement, the ISRLR model significantly improved prediction accuracy, constraining calculation errors to within +/- 25% for axial capacity and 3 similar to 10% for flexural capacity relative to test results. Based on the ISRLR model, the momentaxial force (M-N) interaction curves of RC columns before and after blasting were constructed, and a parametric analysis was performed. The residual bearing capacity based on ISRLR was incorporated into numerical simulations through an engineering case study, the errors in length, width and height of rubble pile were 1.6%, 6.4% and 7.6%, respectively, markedly outperforming the traditional element deletion method. Furthermore, sensitivity analysis demonstrated the model's robustness against uncertainties in material properties and blasting cuts. These findings indicated that the ISRLR model provided a more accurate model for predicting the residual bearing capacity of RC columns after blasting, offering a theoretical basis for the refined design of structural blasting demolition schemes and blasting cuts.

To reveal the bearing and instability mechanisms after filling proppants in the blasting pressure-relief fracture, four types of proppant-containing sandstone composite construction with interface inclinations of 0°, 4°, 8°, and 12° were prepared. A uniaxial compression test was conducted by combining Acoustic Emission (AE) monitoring and camera observation to analyze the variation patterns of peak strength, AE ringing count, b-value, critical slowing down indicators and failure mode. The results show that the average peak stress decreased from 48.55 MPa to 39.30 MPa as the inclination increased from 0°to 12°, corresponding to a reduction of approximately 19.0%. AE ringing counts remained low during the compaction and elastic stages but developed into concentrated bursts before peak stress. The b-value as a whole exhibited the characteristics of "high-level fluctuation—phased decline—low value before peak stress", reflecting the transformation of the crack scale from microcrack initiation to macroscopic penetration. The variance and autocorrelation of AE ringing counts increased before the peak stress and provided warning windows for the instability of specimens. The failure mode gradually transformed from axial splitting to compression–shear failure with increasing inclination.

During the construction of bank slopes involving pile driving, ensuring slope stability is crucial. This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions. Based on the Huarong Coal Wharf project, various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients. The optimal scheme is then identified. Under the selected support scheme, a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads. A time-history analysis is performed to assess the slope's dynamic stability. The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm, respectively. The maximum principal stresses remain below 20 MPa in both rows, while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row. The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz, with a frequency bandwidth ranging from 0 to 500 Hz. The stability coefficient of the pile structures varies over time during the pile driving process, ultimately reaching a value of 1.26-exceeding the required safety threshold. This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.

Rubber-steel fiber concrete (RSF-C) is a new type of composite concrete material that is mixed with rubber particles and steel fibers in normal concrete (N-C). To investigate the dynamic mechanical characteristics and damage-fracture mechanism of RSF-C under impact splitting, comparative impact splitting tests were carried out on three concrete disc specimens: N-C, steel fiber concrete (SF-C), and RSF-C using the SHPB test system. The results showed that: (1) The impact splitting tensile strength showed the obvious steel fiber reinforcing effect, rubber content weakening effect (substitution ratio increases), and rubber particle size enhancing effect (particle size increases). (2) The degree of failure of the specimens increased with the increase of impact load, especially in the "triangular compression-shear fracture zone" formed at the loading ends of the N-C and SF-C specimens due to impact load, and even "semicircular bending fracture" occurred with the increase of impact load. However, the formation of the obvious "triangular compression-shear fracture zone" at the loading ends of the RSF-C specimens needs to occur under relatively larger impact load conditions. (3) Mixing steel fiber and rubber particles obviously increased the toughness of N-C, and the decrease of rubber particle size increased the crack resistance of RSF-C. However, the weak interface formed by rubber particles and cement paste also weakened the bearing capacity of the specimen, increasing the degree of damage with the increase of rubber substitution ratio. (4) For the internal structure of the N-C disc, if the material is homogeneous and continuous in all directions or the homogeneity and continuity in all directions of the edge area of the disc specimen are better than those in the central area, that is, there are more structurally weak surfaces in the central area of the disc specimen, then it is easier to meet the requirement of "the initial crack starts at the center of the disk" in the Brazilian splitting experiment. Conversely, it is more likely that "the initial cracks start from the loading ends of the disc" will occur. (5) For the internal structures of SF-C and RSF-C discs, even if there are many structurally weak surfaces in the central areas of the disc specimens, if the central areas of the disc specimens have better crack resistance due to the presence of reasonable steel fibers, then they are more likely that "the initial cracks start from the loading ends of the disc". Conversely, it is more likely that "the initial crack starts at the center of the disk".

To investigate the effects of wet-dry cycling on the dynamic tensile strength and failure characteristics of limestone, this study conducted dynamic impact loading experiments on limestone specimens subjected to varying numbers of wet-dry cycles using a Split Hopkinson Pressure Bar (SHPB) system. By integrating digital image correlation (DIC) and fractal analysis, the stress-strain evolution, crack propagation patterns, and energy dissipation mechanisms under different loading rates and wet-dry conditions were systematically analyzed. Results indicate that wet-dry cycling significantly degrades limestone’s mechanical properties, reducing tensile strength and promoting complex crack propagation. Energy distribution and dissipation were also substantially influenced. While dynamic tensile strength improved with increasing loading rates, the weakening effect of wet-dry cycles became more pronounced. Additionally, interactions between main and secondary cracks grew more intricate with prolonged cycling. The fractal dimension of fragmentation increased linearly with cycle number, though sensitivity gradually declined. These findings advance the theoretical understanding of limestone failure mechanisms under coupled wet-dry cycling and dynamic loading. They also offer practical insights for mining engineering and blast design applications.

This study investigates the dynamic crack propagation mechanism in damaged rocks under blasting excavation in complex geological conditions. A novel rock fracture analysis method based on pre-compression-induced random damage is proposed, overcoming the limitations of traditional prefabricated crack models. Innovatively, multi-level cyclic static pre-compression is applied to simulate the random damage distribution in engineering-scale rocks, combined with high-resolution computed tomography (CT) imaging to achieve non-destructive 3D visualization of internal crack morphologies under explosive loading. A theoretical model for predicting blast-induced crack propagation radius in damaged sandstone is established and validated through integrated laboratory blast experiments, CT scanning, and PFC-2D numerical simulations, demonstrating a prediction error margin below 5%. Key findings reveal a significant positive correlation between sandstone damage levels and the expansion range of blast-induced cracks as well as crater dimensions. The pre-existing crack network in damaged rocks effectively guides gas wedging effects, unveiling a “weakening-synergistic fracturing” dual mechanism. These results provide theoretical foundations and technical support for optimizing blasting parameters and mitigating dynamic disasters in tunnel engineering under complex geological settings.

To investigate the propagation mechanisms of stress waves and the characteristics of crack distribution in tunnel structures subjected to explosive effects, an experimental model simulating rock mass using cement mortar was employed. Blasting experiments were conducted at various vertical locations relative to the tunnel. Utilizing ultra-dynamic strain monitoring alongside high-speed digital image recognition, we captured in real time the dynamic evolution of stress waves as well as the precise initiation and expansion paths of cracks. A comprehensive analysis was performed on both stress wave propagation and damage patterns within the refuge structure. Furthermore, the reliability of our numerical simulation algorithm was validated through an examination of fluid-structure coupling algorithms. The results indicated that peak strains at monitoring points within the tunnel increased as detonation points approached it, leading to heightened structural damage. Numerical simulations demonstrated a strong correlation between observed peak strains at critical locations and corresponding damage data from our experimental model. Additionally, it was found that decreasing height between detonation points and the tunnel resulted in increased dynamic response parameters-such as overpressure, velocity, and acceleration-at monitoring sites within the tunnel, thereby exacerbating damage to key areas including vaults and footwall structures. To mitigate potential structural instability within refuges, a full-section molded concrete lining support system was implemented along with supplementary anchor (mesh) spraying in critical regions to ensure long-term operational safety.

To increase the efficiency of deep-hole blasting driving in mine rock tunnels, an innovative pattern of wedge cutting blasting with hole-inner delay was proposed. First, the blasting mechanisms of conventional and innovative wedge cutting patterns were theoretically investigated. The results showed that the resistance from large upper rock blocks and the clamping action from the surrounding rock were the major challenges of conventional cutting methods. For the innovative cutting pattern, under the conversion of the spatial distribution and release sequence of blasting energy, the first blasting of the upper charge can strengthen the breaking of the upper rock mass and create a new free surface, which provides favorable conditions for the delayed blasting of the bottom charge. Second, finite element models of two cutting patterns were established and solved, and the simulation results visually revealed the propagation of a stress wave. Critically, the stress strength in the upper cavity increased by 66-83% under the action of the upper charge, which was conducive to the breaking of the upper rock mass and the generation of a new free surface. Therefore, the rock mass in the bottom cavity can be readily broken and discharged. Ultimately, field applications were executed in a rock tunnel. Compared with a conventional cutting pattern, the proposed innovative cutting pattern can prominently increase the cycle advance and hole utilization and greatly reduce the unit consumption of explosives and detonators. This research confirms the usability of the innovative wedge cutting pattern with hole-inner delay in deep-hole blasting driving of rock tunnels.

为研究聚能穴锥角参数对爆炸应力和岩石损伤破裂范围的影响,以获得最优的聚能穴参数,从而达到最佳的破岩效果,利用有限元模拟软件LS-DYNA建立了6 种锥角参数下的单向聚能药柱模型.锥角的深度为 15 mm,6 种锥角高度分别为10、12、14、16、18 mm和20 mm.研究了岩石裂纹扩展的影响规律,测得聚能方向与非聚能方向上不同位置的有效应力,得到不同锥角参数对应的岩石单元的最大破坏距离.结果表明:聚能锥角会对爆破产生定向作用,特别是对岩石破碎和拉伸裂纹所带来的破岩效果影响明显;当锥角高度为 10 mm时,距炮孔 25 cm测点处聚能方向上的有效应力比非聚能方向同样距离处高110.8 MPa,同时,聚能方向上单元损伤比要比非聚能方向高21％,聚能效果最佳;随着锥角高度逐渐增大,聚能方向上岩石裂纹逐渐减少,裂纹分叉减少,单元破坏最大距离可达108.1 cm,并且呈下降趋势.

To study the particle size distribution and energy variation law of hard coal under a load, an impact compression test of hard coal specimens under different impact loading conditions was carried out using a Φ50 mm diameter Separate Hopkinson Press Bar (SHPB) test system. We implemented the theory of dynamic impact energy of rock to establish the calculation expression of hard coal impact crushing energy dissipation, and we established the Weibull distribution model of a crushing body to analyze the impact velocity in relation to the particle size distribution of hard coal crushing and crushing energy consumption. The results demonstrate that due to the different original states of the specimens, the damage to the specimens under static action is in the mode of conjugate plane shear damage, single bevel shear damage, and tensile damage. The damage process of the specimen under impact load loading is divided into three stages: elastic deformation, elastic–plastic deformation, and plastic softening, while the increase in the strain rate caused the peak stress of the specimen to increase. The Weibull distribution can characterize the impact crushing size distribution of hard coal specimens very well. The parameter of coal rock crushing degree is a power function that is influenced by the impact velocity; the greater the impact velocity, the higher the coal rock crushing degree, but the characteristic index of coal rock crushing fluctuates with the increase in impact velocity. As the impact velocity increases, the incident energy and reflected energy increase linearly, while the transmitted energy increases first and then decreases. The dissipation energy of coal rock crushing also increases linearly with the impact velocity. There is no obvious regular change between the energy dissipation rate of coal rock and impact velocity during impact damage, and the dissipated energy of macroscopic crushing only accounts for 10~20% of the incident energy; most of the energy is used for damping loss and damage loss.

为探究应变率对饱水凝灰岩力学特性及破碎破裂形态的影响,采用电液伺服压力机及直径50 mm变截面分离式霍普金森压杆(SHPB)试验装置对干燥及饱水凝灰岩试件开展不同应变率下的单轴压缩试验,并结合高速摄像技术,研究饱水作用及应变率对凝灰岩样纵波波速、峰值应力、弹性模量、能量耗散及破裂破碎特征的影响.结果表明:试件饱和含水率随孔隙度的增大呈线性增长,含水率的增大提高了试件纵波传播速度.静载作用下饱水试件峰值应力、弹性模量均低于干燥试件,饱水作用对岩样造成劣化;随着应变率的增大,饱水试件峰值应力、弹性模量增幅均大于干燥试件,应变率达到130s-1时二者峰值应力相近,动载作用下饱水试件存在水岩动力耦合强化作用.载荷作用下干燥试件的破碎耗能密度高于饱水试件,随着应变率的增大,饱水岩样破碎耗能密度增幅明显高于干燥岩样,高应变率下水的存在增强了凝灰岩的耗能能力.静载作用下试件呈剪切破坏形式,动载作用下试件劈裂拉伸破坏和轴向压缩破坏共存,饱水试件破坏程度显著高于干燥试件.

针对岩巷中深孔掏槽爆破效果差的问题,设计了基于切缝装药定向预裂的中深孔掏槽爆破方案.首先从理论上分析定向预裂对槽腔形成的影响,然后开展掏槽爆破数值模拟揭示槽腔岩体的破坏历程和破坏机制,最后通过现场试验探究其应用效果.结果显示:预裂孔中的切缝装药爆破后沿预裂孔连线会形成定向预裂面,定向预裂面具有自由面反射拉伸效应和应力波阻隔效应,能够促使槽腔岩体充分破坏以形成易于抛掷的岩块,且定向预裂面可以降低成腔阻力,有利于掏槽孔爆破成腔;数值模拟实现了槽腔岩体破坏过程的可视化,通过模拟结果证明了定向预裂面的自由面反射拉伸效应和应力波阻隔效应;相比于现有普通中深孔掏槽爆破技术,在岩巷中深孔爆破采用该掏槽技术时,平均循环进尺增加了 0.29 m,平均炮孔利用率提高了 11.6％,平均炸药单耗降低了 0.19 kg/m3,平均雷管单耗降低了 0.13发/m3,结果验证了此新型掏槽技术在岩巷中深孔爆破的适用性.

To acquire a satisfying cutting effect during medium-length hole blasting driving of rock tunnels, an improved wedge cutting blasting method with supplementary blasting of the center holes was proposed. Initially, the cavity forming mechanism of the improved cutting method was analyzed theoretically. The results suggested that cutting hole blasting could realize the ejection of rock within the range from free face to critical cutting depth, and hence reduce the restraining force of the center hole blasting, and the supplementary blasting of the center holes could further accomplish the expulsion of the residuary rock. Subsequently, simulation of the improved cutting method was implemented to exhibit the stress wave evolution and reveal the stress field distribution. The simulation results indicated that cutting hole blasting could cause the preliminary failure of the residuary rock, and center hole blasting could strengthen the stress field intensity in 1.8–2.5 m in order to aggravate the destruction of the residuary rock. Hence, the residuary rock could be broken into small fragments that were easy to expel out. Finally, a field application experiment was conducted in a coal mine rock tunnel. Using the improved wedge cutting method instead of the conventional wedge cutting method, the full-face blasting driving efficiency was obviously enhanced and the overall blasting driving expense was significantly reduced, which forcefully confirmed the engineering usefulness of the improved wedge cutting method in the medium-length hole blasting driving of rock tunnels.

为了研究炮孔不同耦合系数时的爆破效果,以满足现有煤矿岩巷掘进高效破岩的需要.通过对岩石的爆炸粉碎区和裂隙区范围进行探究,并且利用非线性动力模拟软件,模拟了在孔径32 mm、35 mm、42 mm情况下分别装入可装入的直径27 mm、29 mm、35 mm、42 mm药卷工况时的爆破效果,得到不同耦合系数装药的爆破过程和距炮孔中心不同位置的有效应力峰值;对不同时点岩石各个位置受到的有效应力峰值以及之后应力变化进行可视化表达;以及将各种情况下同一点所受到的峰值应力进行比对.结果表明:随着至炮孔中心距离的增大,应力峰值迅速衰减,且耦合装药无论在近处还是远处,其有效应力峰值的衰减程度均小于不耦合装药;耦合装药周边岩体受到的有效应力远远大于不耦合装药,且炮孔直径越大,有效应力峰值越大;耦合装药较之不耦合装药,有效应力峰值衰减相对较慢;不耦合系数相比较于炸药直径对有效应力峰值影响更大.且通过得到的裂隙圈半径,对单位炸药威力进行量化计算比对,得到采用42 mm炮孔耦合装药时,模拟单位炸药威力为447.02 mm2,更加适合施工现场采用.

Considering the low efficiency of cutting blasting in hard rock mine tunnels, a novel solution of increasing the charge diameter of the cutting holes was put forward. To investigate the influence of the charge diameter on the cutting blasting results, three different working conditions of Φ 32 mm, Φ 42 mm, and Φ 50 mm blasting holes combined with Φ 27 mm, Φ 35 mm, and Φ 45 mm cartridges, respectively, were taken as the investigation objects. At first, the theoretical destruction ranges of single cutting holes under the three different charge diameters were computed. The computed results showed that the destruction range of the cutting holes could be expanded by increasing the charge diameter, which would be beneficial to the destruction of the rock far away from the cutting holes in the cutting cavity. Subsequently, numerical simulations of cutting blasting under the three different charge diameters were performed to display the dynamic propagation process of the blasting stress wave. Importantly, the stress field intensity in the cutting cavity was enhanced significantly with the charge diameter. The stronger stress field intensities generated by the larger diameter charges were more conducive to breaking the rock in the cutting cavity into small fragments that were easy to be discarded. Ultimately, a hard rock vertical slope was used instead of the driving face to carry out the cutting blasting experiments, and the hole utilizations of the cutting blasting were 70.4%, 82.0%, and 94.0%, respectively, under the three different charge diameters, from small to large. The experimental results forcefully substantiated that a higher cutting blasting efficiency could be achieved by increasing the charge diameter of cutting holes in hard rock mine tunnels.

To improve the cutting efficiency in the deep hole blasting of rock roadways, a straight hole cutting blasting technique with supplemental blasting of the central hole was developed. First, the blasting mechanisms of the traditional and novel cutting methods were analysed theoretically. For the novel cutting method, the upper uncharged part of the central hole still acted as empty hole. Cutting hole blasting could eject most of the rock mass in the cutting cavity and hence produce a new free face to weaken the clamping effect of central hole blasting. Then, the residual rock mass could be fully removed after central hole blasting. Second, simulation of the new cutting mode was conducted, which visualized the stress wave forming process. Simulation results showed that the rock mass at the bottom of the cutting cavity could be predamaged by the stress wave caused by cutting hole blasting, and the high-intensity stress field generated by central hole blasting would lead to further damage to the residual rock mass. Thus, the residual rock mass could be thrown out readily. Finally, the auxiliary roadway of an iron mine was selected for the blasting experiments. After statistical analysis, due to the supplemental blasting of the central hole, the average blasting footage was increased by 0.35 m, and the average specific charge was reduced by 0.43 kg·m−3, which validated the predominance of the novel cutting method in the deep hole blasting of rock roadways.

Before rock burst, coal, and gas outburst dynamic load, rock mass in geotechnical engineering has been an indifferent degree of damage. The dissipation energy of rock mass under dynamic load reflects the difficulty of rock breaking. In view of the energy dissipation of damaged rock mass under dynamic load, the cyclic loading and unloading test is carried out to make sandstone in different damage states, and the damage degree of sandstone is characterized by the change of longitudinal wave velocity before and after cyclic loading and unloading. Then, the rock with different damage degrees is tested by adopting the split Hopkinson pressure bar (SHPB). Finally, the energy dissipation characteristics of damaged rock under impact load are analyzed. The results show that the damage factor of sandstone increases with the increase of the upper limit of stress after cyclic static loading. The dynamic strength and peak strain of damaged sandstone increase with the increase of impact pressure and decrease with the increase of damage degree. With the increase of damage degree of sandstone, the reflection energy and dissipation energy of sandstone increase, while the transmission energy decreases.

A double wedge cut was used to improve the cut effects in the medium-depth hole blasting of rock roadways. First, the cavity formation mechanisms of single wedge cut and double wedge cut were analysed theoretically. The results show that the cavity formation resistance of the second-order wedge cut is reduced by the first-order wedge cut. Second, simulations of the two cut modes were conducted, which visualize the stress wave evolution and indicate that the stress wave of the first-order cut holes can cause pre-damage to the rock mass in the second-order cut cavity. A comparison of the stress field distribution shows that the first-order cut holes significantly increase the stress field intensity within 0 ~ 1.6 m to enhance the failure of the rock mass in the first-order cut cavity. Hence, the rock mass in the first-order cut cavity can easily be thrown out to create a new free face, which reduces the clamping effect of the second-order wedge cut and exacerbates the tensile failure of the rock mass in the second-order cut cavity. Thus, the difficulty of second-order wedge cut is reduced. Finally, blasting experiments were performed in a rock roadway. Using the double wedge cut, the average footage increased by 0.31 m, the average utilization rate of blastholes increased by 12.4%, and the average specific charge decreased by 0.20 kg·m−3, which proves the superiority of this cut mode.

To overcome the problems of poor cutting effects in hard rock roadways, a cut blasting technique with large diameter charges was developed; that is, the cut holes employ 50 mm diameter blast holes and 45 mm diameter explosive sticks, while the other holes adopt 42 mm diameter blast holes and 35 mm diameter explosive sticks. First, the effect of charge diameter on damage range and cut cavity formation was analyzed. Next, simulation of wedge cut for different charge diameters was conducted to reveal the stress wave developments and compare the stress field intensities. Finally, field tests were conducted to verify the viability of this technique. The results indicate that large diameter charges can increase the damage range around cut holes to improve the fragmentation degree of the rock mass in the cut cavity and significantly enhance the cavity formation power to better expel the rock mass fragments. The stress wave evolution of wedge cut was visualized using numerical simulations, which confirmed that the use of large diameter charges in cut holes increases the stress field intensity in the cut cavity and hence increases the damage degree of the rock mass. In this study, the use of a large diameter charge for cut blasting increased the average footage by 0.30 m, and the average utilization rate of blast holes increased by 12.5%. Therefore, the cutting effects in hard rock roadways can be improved by using large diameter charges, which increase the blasting footage and the utilization rate of blast holes.