Rockburst Mechanism Research Articles

A scientometric review of structure rockburst research: current trends and future directions

Based on practical construction experience, it is observed that a significant number of rockburst-prone regions exhibit structural surfaces of varying scales that exert a controlling influence on rockburst. Therefore, it is crucial to review the progress and hotspots in research on structure rockburst from a macroscopic perspective. This paper utilized CiteSpace software to summarize the references on structure rockburst research from the Web of Science Core Collection database from 2003 to 2022. The results include keyword cooccurrence and evolution analysis, and co-citation and cluster analysis. Through the in-depth analysis of structure rockburst literature, the research progress of structure rockburst in indoor experiments, numerical simulation, and on-site micro-seismic monitoring progress, the development trend and research hotspots were evaluated, and the current structure rockburst was discussed. The shortcomings of current research on structure rockbursts are discussed, and future development directions are proposed from the perspectives of structure rockburst mechanism, prediction and prevention measures.

Microseismic monitoring and experimental study on rockburst in water-rich area of tunnel

During the excavation of tunnels in the Hanjiang-to-Weihe River Diversion Project, many rockbursts occurred in water-rich (WR) areas. To study the mechanism of rockburst under such conditions, the features of microseismic events and rockbursts in WR tunnel sections excavated by both a tunnel boring machine (TBM) and “drilling and blasting” methods were statistically analysed and compared with those of adjacent water-poor (WP) areas. The results show that in both WR and WP areas, rockbursts are related to the classification of surrounding rock and are also affected by the excavation method. The rockbursts in most WP areas are more active than those in the nearby WR areas in sections excavated by TBM. However, the opposite is true under high in situ stress conditions. To explain the microseismic monitoring results, the mechanical behaviour of rock, including short- and long-term mechanical behaviour under different water and loading conditions, was also investigated, and the results show that under high stress conditions, water will accelerate the occurrence of rockburst. Therefore, the appropriate method to control rockburst is stress release, which can be achieved by advanced pilot tunnel excavation, hydraulic fracturing, and presplitting blasting, rather than high-pressure water spraying in the surrounding rock.

Influence of Key Strata on the Evolution Law of Mining-Induced Stress in the Working Face under Deep and Large-Scale Mining

When there are multiple key strata in the overburden of a deep coal seam and the surface subsidence coefficient after mining is small, this indicates that the overlying key strata fail to break completely after mining. On this occasion, stress is easily concentrated in the working face, which in turn leads to the occurrence of dynamic disasters such as rock bursts. This study adopted a comprehensive analysis method of field monitoring and numerical simulations to explore the influence of the key stratum on the evolution law of mining-induced stress in the working face. A distributed optical fiber sensor (DOFS) and a surface subsidence GNSS monitoring system were arranged inside and at the mouth of the ground observation borehole, respectively. According to the monitoring results of strain obtained from the DOFS, the height of the broken stratum inside the overlying strata was obtained and according to the monitoring results of surface subsidence, the surface subsidence coefficient was proven to be less than 0.1, indicating that the high key stratum is not broken completely, but enters a state of bending subsidence instead. In order to reveal the influence of the key stratum on the mining-induced stress of the working face, two 3DEC numerical models with and without the key stratum were established for a comparative analysis. As the numerical simulation results show, when there are multiple key strata in the overburden, the stress influence range and the stress concentration coefficient of the coal seam after mining are relatively large. The study revealed the working mechanism of rock burst accidents after large-scale mining and predicted the potential area with a rock burst risk after mining of the working face, which was verified by field investigations. The research results are of great guiding significance for the identification of the working mechanism of rock bursts in deep mining condition and for their prevention and control.

Mode I fracture properties and energy partitioning of sandstone under coupled static-dynamic loading: Implications for rockburst

A series of mode I fracture tests under coupled static-dynamic loading were performed on notched semi-circular bend (NSCB) sandstone specimens using the split Hopkinson pressure bar (SHPB) to investigate the dynamic fracture properties and energy partitioning, which can help further elucidate the rockburst mechanism and its kinetic energy source. The fracture processes were captured by the high-speed camera and the digital image correlation (DIC) technique was used. Effects of dynamic loading rates and static pre-load were then analyzed and highlighted. As the loading rate increases, the crack initiation toughness, crack propagation velocity, crack propagation toughness and energy dissipation (including fracture energy and kinetic energy) all increase, while the proportion of kinetic energy decreases. Low pre-load increases the above parameters compared to no pre-load, while high pre-load does the opposite. All the above behaviors are then explained from a perspective of micro-fracture. The mismatch between energy release and energy requirement for fracture is the cause of the kinetic energy of rockburst, and it can be characterized by the established realistic energy release rate (RERR) index.

Simulation of the Damage and Failure Characteristics of Coal under True Triaxial Static–Dynamic Loads

The damage evolution rules for coal under true triaxial combined static–dynamic loads are important to understand and reveal the mechanism of rockburst in coal mines. The numerical simulation was carried out using FLAC3D to explore the coupling effect of static and dynamic stress, especially the influence of dynamic load parameters. The results show that the increase in dynamic load amplitude not only makes the plastic zone grow exponentially and shortens the damage development time, but also decreases the residual strength of the coal sample, which leads to a much more violent dynamic failure. The stress wave propagation can be more stable in the coal sample with the increase in dynamic load frequency and the development time of the plastic zone also shows synchronous fluctuating features, and when the frequency is like the intrinsic frequency of the coal sample, the dynamic load has a significant stimulation effect. The static and dynamic loads have different damage effects on the coal sample under the true triaxial stress path, the weight decreases in descending order, namely the minimum principal stress, the maximum principal, the amplitude of the dynamic load and, lastly, the dynamic stress frequency, according to the entropy weight method analysis.

Effect of horizontal stress on fractal characteristics of rockburst fragments in coal mining

With the continuous increase in underground engineering depth, the risk of coal–rock dynamic disasters, such as rockburst, is becoming increasingly serious and complex threatening the safety of coal resources. To study the effect of horizontal stress on fractal characteristics of rockburst fragments in coal mining, this paper uses a digital drilling instrument to perform rockburst proneness tests on andesite and granite specimens with different horizontal stresses. Fractal theory is used to calculate the fractal dimension of the rockburst fragments for several combinations of parameters. The residual elastic energy index is combined with the fractal dimension of rockburst fragments to assess the propensity of rockbursts from macroscopic and microscopic perspectives. The experimental results show that the positive correlation between the fractal dimension and the AEF obtained under the two methods. The fractal dimensions of andesite and granite are 1.507–1.80 and 1.734–1.979, respectively. According to the rockburst proneness criterion, it is predicted that andesite and granite are all strong rockbursts under confining pressures of 20 MPa, 30 MPa and 50 MPa. Therefore, it is of some theoretical relevance to investigate the rockburst mechanism in terms of both the AEFand fractal dimensions of fragments under different unloading conditions.

Numerical modelling of rockburst mechanism in a steeply dipping coal seam

Numerical modelling of rockburst mechanism in a steeply dipping coal seam

Energy Accumulation Characteristics and Induced Rockburst Mechanism of Roadway Surrounding Rock under Multiple Mining Disturbances: A Case Study

The source of energy release when rockburst occurs must be determined to understand the mechanisms underlying disaster formation and achieve accurate prevention and control. Although previous research has systematically investigated the energy source underlying rockburst from different perspectives, issues such as an unclear understanding of the energy accumulation state and inaccurate positioning of the energy release source remain to be resolved. In this study, the “1·17” major roof accident in the Danshuigou Mine was used as the background to evaluate and analyze the stress environment and energy accumulation characteristics of roadway surrounding rock under multiple mining disturbances, and the results showed that a super energy package occurs in the surrounding rock of the mining roadway. Subsequently, the evolution process of energy in this region and the mechanism of induced rockburst were elaborated. The results showed that the degree of stress concentration in the surrounding rock of the roadway will increase several times as the number of mining disturbances increases. Under the influence of multiple mining disturbances, the maximum principal stress peak of the surrounding rock of the roadway can reach 5–10 times the maximum principal stress value outside the mining-affected area. A large amount of elastic energy was accumulated in the rock surrounding the roadway, and super-high-density energy packages were formed locally. The maximum energy density value reached 50–185 times the value observed in areas outside the mining-affected zone. Thus, rockburst may be induced when the large amount of energy accumulated in the super energy package is suddenly and violently released; moreover, the degree of energy accumulation in the super energy package is likely closely related to the magnitude of rockburst. These results have important theoretical significance and application value for clarifying the mechanism of rockburst and improving the effectiveness of rockburst prediction and prevention.

Slip instability behavior of block rock masses on dynamic-static combined loads

A rock mass is a system of various scale blocks embodied into one another. Inter-block layers are usually composed of weaker and fissured rocks. On the action of dynamic-static loads, it can induce slip instability between blocks. In this paper, the slip instability laws of block rock masses are studied. Based on theory and calculation analysis finding that the friction force between rock blocks varies with block vibration and the friction between rock blocks can drop sharply, resulting in slip instability. The critical thrust and occurrence time of block rock masses slip instability are proposed. The factors affecting block slipping instability are analyzed. This study has significance to the rock burst mechanism induced by slip instability of rock masses.

Dynamic response and rockburst characteristics of underground cavern with unexposed joint

The existence of joints poses a challenge to the dynamic stability of underground caverns. To investigate the dynamic response of the underground cavern affected by an unexposed joint, a series of SHPB tests were conducted on the marble specimens with a cavern and differently distributed joint, including the cases of joint location dips of 0°, 56°, 90°, 134°, and 180° and the case of no joint. The discrete element method was also adopted to uncover the dynamic failure mechanism of samples. Based on the experimental and numerical results, the effects of joint distribution on the fracturing process, dynamic strength and local stress evolution of underground caverns were systematically investigated. The deformation characteristics, failure patterns, rockburst characteristics and rockburst mechanism were identified for different joint cases. The results showed that the joint has limited influence on the dynamic bearing capacity and failure characteristics of the cavern when the dip θ = 0°, 90° and 180°, but it becomes significant when the dip θ = 56° and 134°. Similarly, when the dip θ falls in the range of 56°∼134°, the maximum principal stress around the cavern will be significantly affected, but not when the dip θ is 0° or 180°. More specifically, different joint distributions can cause four kinds of rockbursts on the cavern: A) strain rockburst at the roof; B) strain rockburst at the floor; C) slip rockburst of wing cracks at the roof; and D) slip rockburst of wing cracks at the floor. When these rockbursts occur, the displacements of surrounding rocks will demonstrate obvious abnormal changes (e.g., characteristic oscillations and sudden changes), and C-type rockbursts generally lag behind A-type rockbursts. In addition, the magnitudes of the strain energy release rate can be identified: D-type rockburst > A-type rockburst > B-type rockburst > C-type rockburst > no rockburst. The findings of this study will benefit the stability analysis and risk control of underground caverns.

Study on stress evolution law and rock burst mechanism in upright fold structure area of deep mine

With the increase in coal mining depth, many rock bursts triggered by fold structures have been observed, but the disaster mechanism is not clear. This research aims at investigating the influence of upright fold structure(UFS) on rock burst mechanisms. The mechanical model and numerical model of the UFS are constructed, and the mining stress evolution law and rock burst mechanism of working face in a UFS area are studied by utilizing engineering practice. The research shows that the occurrence of rock burst disasters in the fold structure area has obvious regional characteristics. The horizontal and vertical stress of the UFS in the horizontal distribution is similar to the periodic variation characteristics of the sine (cosine) curve. The stress state of the UFS area is divided into five areas. The horizontal and vertical stress concentration factors increase first and then decrease with the working face gradually approaching and away from the upright fold syncline axis. A roadway impact risk index I 0 is proposed to determine whether the roadway is damaged, and the mechanism of inducing ground pressure during mining in UFS areas of deep mines is expounded. The control plan effectively reduces the stress levels of surrounding rock in working faces.

Investigation into Occurrence Mechanism of Rock Burst Induced by Water Drainage in Deep Mines

Confined aquifers widely exist in the strata of the Ordos mining area. Water drainage before mining is an effective measure to avoid water inrush disasters caused by the connectivity between mining-induced roof fractures and aquifers. However, rock burst disasters occur frequently in the mining process of many water drainage working faces. The statistics show that the surrounding rock of nine water drainage working faces in five mines has suffered different degrees of rock burst, which seriously restricts the safe, efficient production and sustainable development of ten-million-ton modern mines in China. Based on this, taking the 22,106 longwall working face (LW22106) of the Shilawusu Mine, Ordos, as the engineering background, this paper investigates the occurrence mechanism of water drainage on rock burst in the roof water-rich area by using theoretical analysis, similar material simulation, microseismic measurement and other methods. The main conclusions are as follows: (1) After the drainage of the water-rich area, the pressure relief zone, pressurized zone and pressure stabilization zone are formed in sequence from the center to both sides. The width of the pressure relief zone is consistent with that of the water-rich area, and the width of the pressurized zone is about 35 m on one side. (2) When the mining is passing the pressurized zone, the coal rock mass is under the joint influence of gravity stress, mining disturbance stress and drainage transfer stress. The superimposed stress generally exceeds 2.5 times the uniaxial compressive strength (UCS) of the coal rock mass, and the maximum reaches 3.24 times, far exceeding the critical value of rock burst (1.5 times UCS), which is the main reason to induce rock burst. (3) The dynamic change in the rock burst risk areas before and after drainage in water-rich area no. 4 has been predicted, and the number of risk areas increases from 4 before drainage to 13 after drainage. Since the stress superposition effect differs due to different mining speeds, it is proposed that the dynamic regulation of mining speed in the front and at the back of the drainage area is an effective and efficient method for rock burst prevention and control. The research results will provide a theoretical basis and technical support for the prevention and control in the roof water-rich area of deep mines.

Mechanism and Empirical Study of Rockburst in the Adjacent Area of a Fully Mechanized Top-Coal Caving Face Based on Microseismic Technology

Monitoring and providing warnings for coal mine rockburst disasters is a worldwide problem. Several rockburst accidents have occurred in a 1301 belt transport chute near a 1300 fully mechanized caving mine face. To address this issue, an empirical study of the occurrence mechanism of rockbursts in the adjacent area of the fully mechanized top-coal caving face was carried out. This paper mainly addresses the following issues: (1) based on microseismic monitoring technology, the distribution characteristics of the host-rock-supported pressure of the 1300 working face were measured, and the evolution and distribution of the deep-well caving working face host-rock-supported pressure were analyzed. It is revealed that the occurrence mechanism of rockburst in the adjacent area is actually caused by the evolution and superposition of the lateral abutment pressure of the 1300 stope, and the stress of the original rock along the 1301 belt transport down chute; (2) a theoretical calculation model of dynamic and static abutment pressure in longwall stope is built, and an example is tested. The results show that the peak position of lateral abutment pressure of the coal body outside the 1300 goaf is around 63 m, and the peak value of abutment pressure is around 47 MPa; (3) coal body stress monitoring, bolt dynamometer detection, and other means are compared and analyzed. At the same time, with the help of CT geophysical prospecting and drilling cutting measurements, it is concluded that the 1301 belt transport down chute is in the bearing pressure influence zone (superimposed zone), which further verifies the validity of microseismic analysis results and the accuracy of the above theoretical model. Based on this, the early warning system and prevention measures for rockburst based on microseismic monitoring are proposed. The engineering practice shows that the dynamic and static bearing pressure distribution and evolution law of the working face can be dynamically obtained by using microseismic technology, which provides a basis for the accurate prediction and treatment of rockbursts.

Study on Stress-Type Rockburst Mechanism Based on Continuous-Discontinuous Element Method

Abstract Rockburst plays a serious threat to personnel and equipment during underground engineering construction. The study of the rockburst mechanism is helpful to its prediction and prevention. Based on the characteristic analysis of a large number of rockburst cases, Li et al. proposed three stress-type and three stress-structural rockbursts and obtained the geological characteristics and occurrence criteria of these rockbursts, but the evolution process of rockbursts is still unclear. Based on the continuous-discontinuous element method, the characteristics of failure process, surrounding rock stress, motion, and energy of three stress-rockburst blocks are analyzed. The results show that rockburst failure generally goes through several stages, such as a few surfaces tensile failure, shallow shear failure, deep extension of tensile failure, shear failure communication, and rockburst occurrence. The total volume of rockburst blocks and the main distribution intervals of block diameters for different types of rockbursts are quite different, which are mainly affected by stress state and geological structure. The ejection velocity of the small block is always higher than that of the large block during the same one rockburst simulation, and the ejection velocity of the small block is from the surface. In the process of rockburst, not only the elastic strain energy is released but also the elastic strain energy is accumulated. The greater the rockburst intensity, the more the elastic strain energy is released, and the steeper the prepeak curve of elastic strain energy. The research results provide a reference for further understanding the mechanism of rockburst and lay a theoretical basis for the prevention and control of rockburst in underground engineering.

Influence of water on rockburst of surrounding rock in deep circular tunnels under triaxial internal unloading conditions

Rockburst is one of the most serious engineering geological hazards encountered in deep rock mass. In this study, we investigate the influence of water on the rockburst mechanism in circular tunnels considering the whole stress path of high in situ stress + internal unloading + stress adjustment, based on external loading-internal unloading (ELIU) tests on intact air-dried and saturated sandstone cubic specimens (100 × 100 × 100 mm3). The proposed ELIU method uses true triaxial equipment to first load each intact cubic specimen with two-dimensional high stresses, followed by an internal drilling device for internal unloading to form circular holes. For comparison, cubic specimens with predrilled holes 25 mm in diameter were subjected to internal drilling – external loading (IDEL) tests, i.e., drilling first and then loading. The results show that water reduces the uniaxial compressive strength, Young's and initial moduli, and elastic energy storage capacity of sandstone materials, and increases the significance of shear failure. Furthermore, saturated tunnel structures induce static spalling failure, while dry tunnels lead to dynamic rockburst failure. The influence of water on the stability of the rock mass surrounding a tunnel is analyzed, including the induced weakening of surrounding rock strength and the amplification of the unloading effect. In summary, water prevents rockburst through the following mechanism: (i) water reduces the brittleness of the surrounding rock and enhances its plasticity; (ii) water reduces the elastic energy storage capacity and increases the energy dissipation capacity of the plastic zone; and (iii) water induces the redistribution of stress throughout the surrounding rock, which reduces the stress concentration near the free surface and transfers the maximum stress to the deeper surrounding rock.

Failure characteristics and development mechanism of fault rockburst in a deep TBM tunnel: a case study

Failure characteristics and development mechanism of fault rockburst in a deep TBM tunnel: a case study

Evaluation of rockburst risk in deep tunnels considering structural planes based on energy dissipation rate criterion and numerical simulation

Risk evaluation of rockbursts is crucial for ensuring the safety and stability of deep-tunnel construction. Structural planes play an important role in the potential for rockbursts to occur, and more related studies are needed. In this paper, a new rockburst criterion based on energy dissipation rate (EDR) index was developed and the role of structural planes in rockburst potential was studied. Firstly, a method of generating structural planes and a viscoplastic constitutive model with internal variables were introduced for numerical simulation using FLAC3D. Then, tunnelling under different hydrostatic pressures was simulated to obtain the values of EDR index and stress-strength/strength-stress ratio indices, and EDR criterion was estimated based on stress-strength/strength-stress ratio criteria. The results show that EDR criterion is: 0∼1 Pa/s (no risk), 1∼3 Pa/s (low risk), 3∼6 Pa/s (medium risk), >6 Pa/s (high risk). Subsequently, the case study of rockbursts in the drainage tunnel of Jinping II hydropower station was conducted considering a nearby fault to validate EDR criterion. The simulation results using EDR are basically consistent with actual rockbursts in terms of the potential location, intensity and time. Finally, the numerical simulations of tunnel excavation considering a joint set with different dip angles were implemented, and the influences of joints on rockbursts were investigated using EDR. Analysis results show that rockbursts are prone to occur on tunnel walls parallel and perpendicular to joints; potential rockburst locations are controlled by local joints and are less affected by geostress distribution. Joints may increase the intensity, delay the occurrence time, and control the pit boundaries of rockbursts. Obtained EDR contours can be used to infer damaged zones of strainbursts and strain-structure slip rockbursts and understand inducing mechanism of rockbursts in Jinping II drainage tunnel. The findings of this study provide insight into the role of structural planes on rockbursts. The presented methodology can be applied to rockburst evaluation and prevention during the construction of deep tunnels.

Evolution and Control Mechanism of Rockburst in Rock Anchored by New Energy-Absorbing Material

Evolution and Control Mechanism of Rockburst in Rock Anchored by New Energy-Absorbing Material

Crack Evolution Behaviors and Bursting Liability of Sandstone with Different Sizes: An Experimental Study.

The size ranges of ore pillars play important roles in preventing the occurrences of rock burst phenomena. Due to the lack of research on the relationship between crack evolution behaviors and bursting liability of rocks with different sizes, uniaxial compression tests on sandstone with different height-to-diameter ratios (H/D) were conducted. The results showed that the mechanical parameters of sandstone have obvious size effects, in which both the peak strength and peak strain decrease with increases in the H/D. Moreover, the brittle index modified value (BIM) decreased, but the impact energy index increased gradually, which indicated the increase of bursting liability. With the increases in the BIM, the overall crack strain parameters increased, thereby indicating a positive correlation. With the increase in the impact energy index, the crack strain decreased and the bursting liability became higher. Although the axial crack closure stress and axial crack damage stress increased with the increases in BIM (indicating a positive correlation), the bursting liability became increasingly smaller. The crack stress decreased with the increases in the impact energy index, and the bursting liability became stronger. The findings of this study will potentially provide experimental references for furthering the current understanding of the mechanism of rock bursts in underground coal mines in China.

Mechanism of rock bursts in a large inclined extra-thick coal seam under the condition of upper slice mining: a case study

With the increase of mining depth and mining intensity of the large inclined extra-thick coal seam (LIETCS), the number of rock bursts increases significantly. In this paper, based on a rock burst during upper roadway driving of the LIETCS, the distribution characteristics and fracture mechanism of microseismic (MS) events are analyzed using data statistics and seismic moment tensor inversion. By means of mechanical analysis and numerical simulation, this paper studies the static load distribution characteristics and dynamic load action effect of the LIETCS under upper slice mining condition. Based on the theory of dynamic and static combined load, the mechanism of rock bursts is proposed. The results show that the coal and rock mass of the LIETCS are mainly destroyed by shearing. The “shear-clamping” stress produced by the joint action of the roof and floor is the static load source. In upper slice mining, the shear stress and energy of the coal pillar behind the slice and the coal body below the coal pillar always remain high. Under the superposition of floor dynamic load, the regional stress environment changes, which induces rock bursts. This study provides a theoretical basis for rock burst prevention under similar conditions.