With a gradual increase in coal mining depth, the underground geological situation is more complex and the threat of rock bursts is more prominent due to the cross influence of multiple factors, such as faults, thick hard roofs, coal pillars, and high in situ stress areas. Additionally, it is difficult to test the effectiveness of multiple pressure relief measures after implementation in mining areas with rock burst dangers. By evaluating the geology and mining conditions of panel 5308 of the Tangkou coal mine, pressure relief prevention and control technology, combining pre-pressure relief and a danger relief measure, was proposed. An evaluation method for pressure relief implementation in deep mine rock burst danger areas was proposed, with changing rates of event frequency in microseismic high-energy intervals, changing rates of the mean values of hydraulic-powered support stress, and changing rates of bursting strain energy as evaluation indicators. The weight of each indicator was determined based on an analytic hierarchy process. The degree of pressure relief was measured by the pressure relief interval index. The comprehensive pressure relief effect index was calculated by an interval index and by a weight vector. Additionally, the classification standard of the pressure relief effect was proposed. The results show that the frequency of microseismic high-energy interval events decreased by 34.9%, the mean value of hydraulic-powered support stress decreased by 12.7%, and the bursting strain energy decreased by 14.7% after pressure relief was applied at panel 5308. Additionally, the interval indexes corresponding to each indicator were 3, 2, and 2 and the pressure relief effect index was 2.55, so the destress effect was good. The drilling method monitoring data show that the average value of the drilling powder decreased by 18% after pressure relief compared with before and the overall effect was good, which is consistent with the evaluation results of the multi-dimensional pressure relief implementation effect evaluation system, indicating that the evaluation system can accurately test the effectiveness of the multi-dimensional pressure relief implementation effect in deep mine rock burst danger areas. The results of the study provide methodological support and reference for the monitoring and prevention of rock bursts in mines with similar geological conditions.

In the process of coal resources development, a large number of strip coal pillars have been left behind in the coal mines in central–eastern China. With the increase in coal mining depth year by year, the rock burst threat of strip coal pillars is becoming more and more prominent due to the influence of buried depth, geological structure, gob and other factors. Backfilling mining is the main means to recover the residual strip coal pillar. In order to investigate the effect of backfilling mining on the prevention and control of rock burst, taking the paste backfilling workface 1# of Gucheng coal mine as the engineering background, a comprehensive research method of theoretical analysis, numerical simulation and field monitoring was used to study the evolution of stress and of the overburden spatial structure of the backfilling workface under the control of the backfilled ratio. The results showed that the backfilling mining controls the movement and deformation of overburden by reducing the activity range of roof strata. The overburden fracture development height decreases with the increase in backfilled ratio, but there is a boundary effect influenced by the roof deflection before backfilling and the defective distance of roof contact. With the increase in backfilled ratio, the concentration coefficient of front abutment pressure, the vertical displacement of the roof and the development height of the plastic zone of overlying strata decreased obviously, which indicates that filling mining can effectively control the stress of surrounding rock and the movement of overlying strata. The field monitoring data showed that the influence range of the front abutment pressure of the paste backfilling workface was about 90 m and the maximum stress of the surrounding rock of the two entries did not exceed 7 MPa. The average daily frequency of microseism was 1.34, and the average daily total energy of microseism was 1.80 + 10³ J, which decreased by 69% and 90%, respectively, compared with the caving method working face with similar geological conditions. The data above showed that the backfilling mining can effectively reduce the working face stress level and dynamic load strength to achieve the effect of prevention and control of rock burst.

Aiming at the problem of the unclear rock burst generation mechanism and anti-impact measures of a large roadway through a coal seam in a deep panel area, taking the rock burst of a large roadway in the first panel area of Gaojiapu Coal Mine as the engineering background, this paper adopts the comprehensive research methods of theoretical analysis, experiments, numerical simulation, fragmentation fractal analysis, and field monitoring, to discuss the mechanical characteristics of the loading process of the assemblage and the energy transfer law and its difference in the deformation and failure process. The possibility and strength of the impact failure of coal under the grip of rock masses with different stiffness are related to the γ value. The smaller the γ value is, the higher the impact possibility is, and the more severe the impact degree is. The assemblage under the grip of soft rock is more prone to system instability. Energy relief and impact reduction are adopted to reduce the post-peak stiffness and elastic strain energy of the coal body in a short distance, avoid the energy transfer and concentration of the roadway surrounding the rock system under the disturbance of a long-distance dynamic load, and reduce the likelihood of impact pressure occurring and the extent to which an impact manifests.

After entering deep mining, coal mines often experience various intense dynamic load phenomena due to increasingly complex geological conditions, which can lead to secondary disasters, where it is urgent to identify their sources and analyze their disaster-causing effects. This article takes the 3310 working face in Gu Cheng Coal Mine as the engineering background, and uses theoretical analysis, numerical simulation, on-site monitoring, and other methods to analyze the spatial and temporal distribution of dynamic load events during the mining period of this face. The study classifies dynamic load events based on this background into roof-type, fault-type, and coal pillar-type classes, revealing the differences in the spectra, waveforms, and disaster-causing effects of each class. The results show that the strong dynamic load events are mainly concentrated in the working face roof and fault zone areas. The first principal frequency of the three classes has an estimated boundary between 30 and 60 Hz. The waveform decay coefficients of the roof-type, coal pillar-type, and fault-type strong dynamic load events have average values of 4.53, 1.57, and 1.41, respectively. By adopting the above research methods, a theoretical basis can be provided for the source of dynamic loads, thereby achieving source-based prevention and control of rock burst.

During drill-and-blast construction, complex and variable rock masses are frequently encountered. Owing to the transient nature of the explosion process and the randomness of crack propagation, the response of different rock masses to explosive loading is highly intricate. This study primarily investigates the dynamic response of rock masses with varying strengths under two different charge configurations. First, four cement mortar specimens of differing strengths were prepared then subjected to general blasting and slit charge blasting, respectively. High-speed cameras and digital image correlation techniques were employed to capture and analyse stress wave propagation and crack propagation during detonation. Fractal dimension analysis was subsequently employed to quantify and compare the extent of damage in the specimens. Findings indicate that rock strength influences stress wave attenuation patterns: lower-strength rocks exhibit higher peak strains but faster decay rates. Crack propagation velocity was calculated by deploying monitoring points along fracture paths and defining fracture initiation thresholds. Higher rock strength correlates with both peak and average crack propagation velocities. Slit charge blasting effectively optimizes damage distribution, concentrating it within the intended directions while reducing chaotic fracturing. These findings provide scientific justification for blasting operations in complex rock formations.

The study of mechanical response and crack propagation behavior of layered composite rock mass is helpful for the efficient extraction of geological energy and the safety and stability of underground space structures. The shale is a heterogeneous rock, which is often mixed with mudstone and sandstone. Studying the propagation law of cracks in layered composite rock mass can better serve underground engineering. In this paper, three different strength rock materials (coarse sandstone, red sandstone, and gray sandstone) were spliced together to make three-point bending specimens with prefabricated cracks in the middle, and three-point bending experiments under different loading rates were carried out. The digital image correlation method was used to visualize the strain distribution in the three-point bending experiment, and the difference in crack propagation in different layered composite rock masses was studied. The numerical simulation is established by the cohesive element, and the correctness of the simulation is verified by the displacement-load data. Then the crack propagation speed under different conditions is studied. The results show that there are differences and similarities in the crack propagation process in different strength gradient composite rock masses. When the crack propagates from strong to weak, the crack tip receives more complex tensile shear force, which facilitates the crack crossing the interface. As the loading speed increases, the earlier the prefabricated crack initiates, the shorter the time it stays at the joint surface. When the crack propagates from strong to weak, the crack propagation is more penetrating.