Blasting Stress Wave Research Articles

Experimental study on pressure relief blasting in rock-blast tunnel

Rock burst is a difficult and urgent problem during the construction process of underground engineering in a zone with high surrounding rock pressure. Pressure relief blasting is one of the most effective methods for solving the problem. An in-situ blasting test was carried out in a tunnel under excavation, and the geology stress (geo-stress) of the surrounding rock was tested before and after the pressure relief blasting. The experimental results will be effective for further study of the law of pressure relief blasting and rock-burst prediction. An explicit stress analytic function is also employed to analyze the stress distribution of the tunnel surrounding rock after pressure relief blasting based on the propagation of the blasting stress wave. Furthermore, the stress attenuation coefficient and the variation of the geo-stress distribution of surrounding rock under the pressure relief blasting were discussed in detail with the in-situ blasting test data. Highlights. The main contribution of this paper is focused on: 1. This study measures the in-situ geo-stress of surrounding rock in the ‘Sang zhu ling’ tunnel, both before and after the pressure relief blasting. This data is crucial for ensuring the safety resilience of urban infrastructure. 2. A two-dimensional explicit equation of stress attenuation was derived based on the characteristics of stress propagation, providing a more accurate analytical tool for engineers and researchers, 3. The traditionally obtained stress attenuation coefficient is shown to require modification through further in-situ experiments. Future studies will refine this coefficient, contributing to the development of more reliable methods for safeguarding urban lifelines. These contributions align with the journal’s focus on advancing urban science and engineering by promoting innovative, data-driven solutions for urban safety.

Analysis of the dynamic response and damage characteristic for the tunnel under near-field blasts and far-field earthquakes

The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances. These characteristics are crucial for assessing structural stability and designing effective support for surrounding rock. In this study, the theoretical solution for the dynamic stress concentration factor (DSCF) of a circular tunnel subjected to cylindrical and plane P-waves was derived using the wave function expansion method. The existing equivalent blast stress wave was optimized and the Ricker wavelet was introduced to represent the seismic stress waves. By combining Fourier transform and Duhamel’s integral, the transient response of the underground tunnel under near-field blasts and far-field earthquakes was determined in both the frequency and time domains. The theoretical results were validated by comparing them with those obtained from numerical simulations using ANSYS LS-DYNA software. Numerical simulations were conducted to further investigate the damage characteristics of the underground tunnel and evaluate the effect of initial stress on structural failure under both types of disturbances. The theoretical and numerical simulation results indicated that the differences in the dynamic response and damage characteristics of the underground tunnel were primarily due to the curvature of the stress waves and transient load waveform. The locations of the maximum DSCF values differed between near-field blasts and far-field earthquakes, whereas the minimum DSCF values occurred at the same positions. Without initial stress, the blast stress waves caused spalling damage to the rock mass on the wave-facing side. Shear failure occurred near the areas with maximum DSCF values, and tensile failure occurred near the areas with minimum DSCF values. In contrast, damage occurred only near the areas with maximum DSCF values under seismic stress waves. Furthermore, the initial stress exacerbated spalling and shear damage while suppressing tensile failure. Hence, the blast stress waves no longer induced tensile failure on the tunnel sidewalls under initial stress.

Study on anti-reflection of deep soft and high gas coal seam floor by deep hole controlled blasting

Addressing the practical challenges of difficult drilling for blasting-induced permeability enhancement in deep, soft, and high-gas coal seams, where fractures remain underdeveloped and prone to re-compaction, this study proposes blasting operations within the floor strata. This approach aims to enhance the permeability of soft coal seams, thereby extending the duration of effective gas extraction. A bidirectional loading gas–solid coupling blasting simulation system was established in the laboratory, enabling multi-faceted analysis of experimental models through macroscopic crack patterns, internal damage mechanisms, and strain data of coal and rock masses. Comparative experiments were conducted, contrasting various control hole spacings with conventional blasting techniques. The findings reveal that as the blasting stress wave traverses the control hole walls, tensile stress waves are reflected, facilitating crack propagation. The guiding effect of the control holes and the spatial compensation they provide significantly increase the extension distance of explosion-induced cracks, resulting in directional failure of the test specimens and heightened damage in the far field of the blast. After the blasting process, the arrangement of control holes can result in an increase of up to 133% in damage to the coal seam and a reduction of up to 167% in damage to the floorboard compared to the model without control holes. Notably, when the control holes are proximal to the coal-rock interface, the near-end coal body experiences the most pronounced effects, with peak damage and tensile strain in the d = 20 mm model being 1.93 and 1.79 times higher, respectively, than those in models without control holes. Conversely, for control holes located further from the interface, the distal coal body experiences the greatest influence, exhibiting 1.53 and 1.55 times higher peak damage and tensile strain, respectively, in the d = 80 mm model compared to uncontrolled counterparts. Field observations at the C13 coal seam of a mine within the Huainan mining area corroborate these findings, where the volume of gas extraction and its concentration experienced a rapid increase following blasting and penetration enhancement. Optimum permeability enhancement occurs when the blasting hole is situated 4 m from the extraction point, resulting in a 131% increase in gas extraction purity from 0.15 × 10–3 m3/min to 1.97 × 10–3 m3/min. Furthermore, gas concentration soars by 373%, from 5.86% to 21.86%. These research outcomes offer valuable insights and hold considerable reference significance for blasting-induced permeability enhancement in deep, soft, and high gas coal seams.

Investigation on Asymmetric Dynamic Response Characteristics of Anchored Surrounding Rock under Blasting Excavation of Inclined Layered Rock Tunnel

The dynamic response stability analysis of the anchored surrounding rock during blasting construction is crucial to ensure the safety of construction. Taking the Wuwan Tunnel in Luoyang as the engineering background, combined with methods such as physical simulation experiments, numerical simulation experiments, and on-site experiments, the asymmetric effects of layered rock mass on the surrounding rock and support structure during blasting excavation were studied. The asymmetric effects of tunnel blasting excavation on the surrounding rock and support system under the condition of a bedding angle of 30° were analyzed and summarized. The results indicate that when the blasting stress wave passes through the bedding plane, the stress wave will undergo significant attenuation. The strain generated by the anchor rod passing through the bedding plane exhibits asymmetry due to the reflection and weakening of the blasting stress wave after passing through the bedding plane.

Research on Damage Evolution Mechanism of Layered Rock Mass under Blasting Load

Rock mass consists of many discontinuities, such as faults, joints, etc., and layered joints are a common kind of rock mass structure. The joints affect the stress wave propagation, and blasting is an economical and efficient rock fragmentation method for rock mass engineering. So, the rock mass fragmentation effect and construction progress are affected by these layered joints. Numerical studies were carried out to analyze the damage evolution process of intact rock and rock mass with layered joints subjected to blasting loads based on the Riedel–Hiermaier–Thoma (RHT) model in LS-DYNA software (smp s R11.0.), and the effects of the location of initiation points and the fracture distribution on dynamic damage evolution of the rock mass were discussed. Bottom initiation tends to direct the blasting energy toward the blasthole mouth, resulting in effective rock fragmentation and ejection. Gradually adjusting the initiation point upward can improve the stress and damage distribution, allowing some of the blasting stress waves to propagate toward the bottom and enhance the fragmentation of the rock at the bottom. The distribution of layered joints exacerbates the damage to the rock mass on the upstream surface, but also acts as a certain shield to the propagation of stress waves, increasing the asymmetry of the damage distribution. It is useful to know the damage mechanism of the rock mass with layered joints to improve the effect of rock mass fragmentation by blasting. These results have very important theoretical significance and application value for the optimization of blasting construction technology.

Theoretical analysis of the scattering characteristics of blasting stress waves at an arc-shaped interface crack in a deep rock mass with high in-situ stress

A mathematical model of blasting stress wave scattering at an arc-shaped interface crack is established to theoretically analyze and verify the scattering characteristics of blasting stress waves at an arc-shaped interface crack in a deep rock mass with high in-situ stress. Based on the continuum mechanics, finite deformation, and incremental stress theories and the geometric and physical characteristics of the arc-shaped interface crack, the mathematical model includes a set of the first class of singular integral equations with Hilbert kernels. The opening and dislocating displacements of the arc-shaped interface crack and the effective stress components of scattered stress waves are numerically calculated and discussed with the variation of the type, frequency, and incident angle of the blasting stress wave; the curvature radius and opening angle of the arc-shaped interface crack. The condition that the dynamic stress intensity factors and energy release rates at the upper and lower tips of the arc-shaped interface crack reach peak are also provided. It is found that when the frequency of the blasting stress wave and the curvature radius of the arc-shaped interface crack increase, the peaks of the above dynamic stress intensity factors will increase further, and the arc-shaped interface crack is more likely to expand or destabilize. Although the order of in-situ stress is much smaller than that of Young’s modulus of the deep rock mass, it increases the effective stress concentration of scattered stress waves and the opening and dislocating displacements of the arc-shaped interface crack. These findings will provide theoretical guidance for analyzing the cracking characteristics of blasting stress waves in deep rock masses with high in-situ stress.

Blast wave interaction during explosive detonation in a variable cross-sectional charge

Purpose. The research aims to assess the efficiency and performance of solid media destruction in directed blasting of a charge with variable cross-sectional shape. Methods. Numerical modelling of the blast wave interaction process is performed using the finite element method based on the Euler-Lagrange algorithm. The Johns-Wilkins-Lee equation of state is used to determine the pressure-volume dependences of medium destruction. Assessment of solid medium destruction mechanism during a directed blasting of a charge with variable cross-sectional shape is carried out based on polarization-optical method on models made of optically active material. Findings. Experimental studies of solid medium destruction by the action of directed blasting with a variable cross-section charge made it possible to determine the direction of blast wave propagation and its amplitude in stress wave, influencing the intensity of radial crack network formation in superposition areas, and directed perpendicularly to explosive cavity. At the same time, the average peak pressure in collision zone of two shock waves in centre of spherical cavity is approximately 1.48 and 1.84 times higher than that in weakly blast-loaded areas. It has been found that when two shock waves collide and superimpose on each other, the intensity of their impact increases. Moreover, the shock wave velocity in collision zone is higher than that of the radial shock wave. Originality. It has been determined that the maximum pressure values on the explosive cavity wall at the initiation points sharply increase and then gradually stabilize as the blast stress waves propagate and have an arbitrary distribution pattern. Three areas should be considered: not superimposed, weakly superimposed, and strongly superimposed. At each point of detonation, the pressure on explosive cavity wall will be minimal, while in the charge centre in the spherical insert zone, on the contrary, it will be maximal. In this case, the pressure in the central superposition area is about 2.84 times greater than at the initiation ends, and the nature of distribution changes according to a linear dependence. Practical implications. The performed research findings can serve as a basis for development of effective parameters of resource-saving methods for stripping hard rocks of complex structure in the conditions of ore mines.

Dynamic response characteristics and damage calculation method of fractured rock mass under blasting disturbance

The mechanical responses and damage characteristics of fractured rock masses under dynamic loads play a significant role in ensuring the safety of blasting operations. The study employs dynamic finite element method (FEM) to simulate blasting in fractured rock masses, revealing the propagation features of blasting stress waves, the evolution of effective stress and the mechanism of damage evolution around the borehole. Based on the Weibull distribution, a rock damage model was established, which yielded the stress-strain relationship and damage equation for rocks under uniaxial impact. The parameters of the damage equation were fitted through numerical SHPB tests. The results indicate that in the direction of higher initial stress, the stress wave propagates faster, and the development of damage surfaces is more pronounced. In cylindrical charge blasting, the maximum blasting stress occurs in the middle section of the borehole, with limited influence from the charge on the bottom of the hole. Within a range of approximately 2 to 3 times the borehole diameter, the surrounding rock sustains complete damage. While within a range of about 4 to 5 times the borehole diameter, the degree of damage to the surrounding rock decreases rapidly, and beyond this range, the damage to the surrounding rock gradually diminishes.

Theoretical analysis of the interaction between blasting stress wave and linear interface crack under high in-situ stress in deep rock mass

This study theoretically investigates the scattering characteristics of blasting stress waves, treaded as elastic waves, at a linear interface crack in a deep rock mass with an even compressive in-situ stress field. First, the basic equations of the deep rock mass theoretically treaded as a homogeneous isotropic medium with an initial stress field are derived based on the linear elastic, finite deformation, plane strain, isotropic, and small deformation hypotheses, and incremental stress theory. The linear interface crack is theoretically treaded as two displacement-free boundaries, of which the interpolation displacements are described by introducing two dislocation density functions. Next, the mathematical model of the blasting stress wave scattering at the linear interface crack is established through a set of singular integral equations of the first type for these two dislocation density functions with Cauchy kernels. Finally, the dislocating and opening displacements of the linear interface crack and the displacement and effective stress fields of the scattered stress wave are numerically calculated. The principal stress field of the scattered stress wave is compared with the experimental data to qualitatively verify the rationality and correctness of the mathematical model. Theoretically, it is found that even compressive in-situ stress with an amplitude of tens of megapascals significantly affects the displacement and effective stress fields of the scattered stress wave near the linear interface crack. In conclusion, considering even compressive in-situ stress is greatly significant when studying the wave and scattering behaviors of deep rock masses. This mathematical model provides a theoretical guidance for the study of stress wave energy transformation and crack propagation in the process of rock blasting and mineral mining.

Study on the superposition effect of stress waves and crack propagation law between blastholes at different angles

The drilling and blasting method is extensively employed in various industries such as mining and infrastructure construction. In the majority of blasting operations, strip-charges are predominantly utilized, while blastholes often exhibit an angled orientation in practical engineering scenarios. To investigate the stress wave superposition effect and the crack propagation law among blastholes at varying angles, this study employs a high-speed digital image correlation system to conduct blasting model experiments. The results indicate that: the fractal dimension of the crack propagation trajectory decreases progressively as the angle increases. the von Mises strain-time curve of the specimen initially increases and then decreases. As the angle between the blastholes widens, the fractal dimension of the crushing zone and blasting crack among the blast borehole decreases accordingly, suppressed the blasting effect of the blasted medium. On the central axis between the two holes, the stress superposition becomes more obvious in the direction away from the initiation point, and the peak value of strain is the highest at the bottom of the blastholes. When the angle between the blastholes is 30°, the strain in the specimen takes the longest to decline from peak to valley, and the blasting stress wave sustains its influence for an extended duration, thus maximizing the use of blasting energy. Conversely, when the angle between the blastholes is 0°, the specimen experiences the shortest duration of blasting action and the least efficient energy utilization.

Damage analysis and safety control of surrounding rock around peripheral hole of diversion tunnel

The control of overbreak in blasting excavation is a significant technical challenge and a subject of extensive research in the field of engineering. This study examines the damage characteristics of the surrounding rock in a tunnel section through blasting test and numerical simulation conducted as part of the San Gavan diversion tunnel project in Peru. The orthogonal test of peripheral holes under the influence of explosive spacing, blasthole spacing and smooth blasting layer thickness was designed to analyze the characteristics of rock damage under different parameter combinations and the influence of various factors on rock damage. Based on the USBM formula, this paper deduces a mathematical model considering blasthole spacing and explosive spacing to predict the rock damage range. The main conclusions are as follows: on the tunnel section, the average damage range of vault and arch springer is slightly larger than that of spandrel and haunch. For a single blasthole, the rock damage range in different sections is: explosive > air > stem, and the degree of rock damage at the bottom of blasthole is the highest. Smooth blasting layer thickness has a significant effect on rock damage rate on the side of non-reflect boundary. When smooth blasting layer thickness is 45 cm and 55 cm, the boundary conditions of numerical model have a significant effect on the rock damage. The reflection of blasting stress wave on the free surface leads to the further increase of rock damage range. The blasthole spacing and explosive spacing have a significant effect on rock damage range on the side of non-reflect boundary, and both show a negative correlation. Based on the prediction model of rock damage, the combination of peripheral hole parameters satisfying the standard is obtained, which provides guidance for blasting design.

Visualization study on stress evolution and crack propagation of jointed rock mass under blasting load

In this study, the simultaneous observation of stress wave propagation and crack propagation was realized through the wave-crack synchronous test, which clarified the stress wave propagation and superposition process of rock blasting with jointed rock. The variation law of crack dynamic parameters (stress intensity factor and propagation velocity) was also revealed. On this basis, numerical simulation study was performed using the CDEM method to analyze the influence mechanism of joint length and in-situ stress condition on the blasting stress evolution and crack propagation. The results showed that the joint had significant effect on the distribution state, the evolution law and the propagation process of blasting crack. The blasting stress wave diffracted from the joint end, propagated along the joint plane and superimposed, causing the stress concentration and crack initiation and propagation at the joint end. The longer the joint length, the longer the diffraction time and propagation time of the blasting stress wave along the joint plane. In addition, the biaxial equal in-situ stresses inhibited the propagation of the blasting crack. The inhibition effect was significantly strengthened with the increase in in-situ stress, while it promoted the initiation and propagation of the blasting crack in the middle of the joint.

Effect of Blasting Stress Wave on Dynamic Crack Propagation

Effect of Blasting Stress Wave on Dynamic Crack Propagation

The Explosive Crack Propagation Mechanism of Layered Rock Mass

Layered joints significantly affect the propagation and attenuation of engineering blasting stress waves and have a significant influence on rock breakage. In this study, the explosion crack propagation mechanism of a stratified rock mass with weak or no cementation is analyzed. Multilayer plexiglass plates are employed to simulate a layered rock mass, establishing an experimental model to investigate the vertical interaction between explosive charges and layered rock masses. The extent of ruptures and damage within the charging and sealing sections of the rock mass is analyzed. The explosion cracks at the bottom of the hole are relatively dense, whereas those at the hole opening are relatively sparse. The range of the crushing and fracture zones around the gun hole in the charging section is larger than that in the blocking section. Moreover, as the blocking section approaches the free plane, the crushing zone size decreases. A notable area of rapid damage escalation is identified between the blocking and charging sections, leading to a significant increase in damage intensity. The numerical analysis results indicate that the cumulative explosive energy within the charging section surpasses that of the blocking section, and the rate of energy accumulation is notably higher in the charging region.

Propagation of P‐SV waves radiated by explosive columns in jointed rock masses

AbstractWhen an explosive column initiates, it will radiate P‐SV waves. The propagation of P‐SV waves, which carry the majority of the explosion energy, is extremely complex in jointed rock masses. Therefore, studying the propagation of blasting stress waves in jointed rock masses is of great significance for optimizing the parameters of the blastholes and improving the economy and safety of geotechnical engineering construction. In this study, an analytical model of the propagation of P‐SV waves radiated by explosive columns in jointed rock masses is derived. Using this analytical model, the maximum displacement distribution in jointed rock masses with the free surface is analyzed, and the results show: (1) when the stress waves propagate to the free surface, the reflected waves will be generated, which will produce the remarkable superposition effect with the direct waves, while the superposition effect will affect the maximum displacements at the measuring points significantly; (2) the amplitude of transmitted waves generated from the stress waves that propagate through the rock joints is smaller than that of direct waves, thus the maximum displacements at the measuring points are affected by the rock joints within a certain range; (3) the velocity of detonation (VOD) and the length of the explosive column can affect the superposition effect of stress waves, ultimately impacting the maximum displacement distribution in jointed rock masses. Therefore, optimizing the parameters of the blastholes reasonably to achieve the optimal superposition of stress waves is of great significance for improving the construction efficiency of geotechnical engineering.

A Numerical Study of the Dynamic Crack Behavior of Brittle Material Induced by Blast Waves.

Blast stress waves profoundly impact engineering structures, exciting and affecting the rupture process in brittle construction materials. A novel numerical model was introduced to investigate the initiation and propagation of cracks subjected to blast stress waves within the borehole-crack configuration. Twelve models were established with different crack lengths to simulate sandstone samples. The influence of crack length on crack initiation and propagation was investigated using those models. The linear equation of state was used to express the relationship between the pressure and density of the material. The major principal stress failure criterion was used to evaluate the failure of elements. A triangular pressure curve was adopted to produce the blast stress wave. The results indicated that the pre-crack length critically influenced the crack initiation and propagation mechanism by analyzing the stress history at the crack tip, crack propagation velocity, and distance. The inducement of a P-wave and S-wave is paramount in models with a short pre-crack. For long pre-crack models, Rayleigh waves significantly contribute to crack propagation.

Experimental study into the propagation and attenuation of blasting vibration waves in porous rock-like materials

Rock blasting vibration can cause harm to the surrounding environment. This article aims to investigate the propagation and attenuation of vibration waves in the blasting excavation of porous rock. Similar materials were used to simulate porous rock media and indoor blasting experiments were conducted on 12 porous rock-like models poured to estimate influences of the media material, porosity, moisture conditions, and decoupling coefficient of blast holes on the propagation of blasting stress waves. The results show that: 1) the crack propagation path of vibration waves in foam ceramics similar materials (FC) is not a completely straight line: cracks tend to produce a large deflection during the development process; 2) damage modes of low-porosity similar materials are mainly dominated by crack development, while damage and failure of high-porosity similar materials involve crack expansion and crushed fragments; 3) the peak vibration acceleration presents exponential decay with the distance, which will not vary with changes in the media material, porosity, moisture conditions, and the decoupling coefficient of blast holes; 4) the peak vibration acceleration of cement-based similar materials (SM) demonstrates the exponential decay coefficient of −1.4 ∼ −1.0, the exponential decay coefficient of the peak vibration acceleration for FC is −0.8 ∼ −0.4. The peak vibration acceleration of high-porosity similar material shows a faster decay rate, which is generally 0.3 less than that of the low-porosity similar material; 5) the type of material exerts the most significant controlling effect on the decay coefficient of peak vibration acceleration, followed by the effects of porosity and degree of water saturation; the decoupling coefficient of blast holes does not exert any significant influence on the decay of peak vibration acceleration.

Study on the Influence of the Joint Angle between Blast Holes on Explosion Crack Propagation and Stress Variation

The joints and fissures in a natural rock mass can affect the mechanical properties of the rock mass, the propagation of a blasting stress wave, and the blasting effect of the smooth surface of roadways. In the process of roadway drilling and blasting, there will inevitably be some joints between the two blast holes. Taking the joint angle as the starting point, this paper studies the rule of rock explosion crack propagation and stress variation when there are joints with different angles between two blast holes and analyzes the influence of joints on rock mechanical properties and blasting effects. The numerical simulation method and the software ANSYS/LS-DYNA are used to establish 7 rock mass models with various joint angles. When there is no joint between two holes and joints of 15°, 30°, 45°, 60°, 75°, and 90°, the propagation of explosive cracks and stress variations in the rock mass are discussed. The results show that the joints at different angles have obvious guiding and blocking effects on the propagation of explosive cracks, and as joint angles increase, the guiding effect becomes more apparent and the blocking effect becomes weaker. The effective stress of the rock mass will vary depending on the angles of the joints between the hole and the joint. As the joint angle increases, the joint’s influence on the reflection and superposition of stress waves gradually weakens, and the peak value of the effective stress of the rock mass gradually decreases. The peak effective stress of the rock mass on the blasting side of the joint is similarly impacted by the superposition of stress waves, and the extreme value may be seen at the critical node of each change curve. The explosive crack will break through at the critical location because the maximal effective stress of the rock mass is distributed in a “W” form on the blasting side of the joint.

Study on the Interaction Between Blasting Stress Waves with Different Incidence Angles and Crack

Study on the Interaction Between Blasting Stress Waves with Different Incidence Angles and Crack

Numerical simulation of rock bursts triggered by blasting disturbance for deep-buried tunnels in jointed rock masses

Frequent dynamic disturbances, such as explosions, vibrations, and earthquakes, may trigger the risk of rock burst disasters around neighbouring deep-buried tunnels. In this study, the PFC software was used to simulate rock bursts triggered by blasting stress waves (dynamic disturbance) to determine their effects on deep-buried tunnels in jointed rock masses. This study investigated the effects of different ground stress values and joint angles on rock bursts in tunnels under intense dynamic disturbance. An analysis of different ground stress values and joint angles revealed the changes in the ejection velocities of damaged rocks and kinetic energy under intense dynamic disturbance. The results show that higher ground stress can alter the proportion of stress waves converted into strain energy and kinetic energy. Joint angles affect the location of the rock burst. The closer the joint angle is to 90°, the greater the damage to surrounding rocks caused by stress waves. Higher ground stress and joint angles increase the risk and intensity of rock bursts, causing significant damage to surrounding rocks, which makes existing tunnels more vulnerable to impact. The findings of this research have important guiding significance to ensure the secure protection of tunnels against rock bursts.