Mechanical Properties of Roof Rocks under Superimposed Static and Dynamic Loads with Medium Strain Rates in Coal Mines

Zhong, Kun; Zhao, Wang; Qin, Changkun; Gao, Hongshuai; Chen, Weizhong

doi:10.3390/app11198973

Cited by 9 publications

(4 citation statements)

References 51 publications

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“…The triaxial stress-strain curve and a photo after the failure of a typical specimen are shown in Figure 3. The failure mode under the true triaxial conditions was mainly shear failure and a significant large crack ran through the samples from top to bottom and, compared with uniaxial compression, the total number of cracks was relatively small, which is similar to the results by Zhao [45] and Zhong [46]. The numerical simulation software FLAC3D was adopted for the simulation.…”

Section: Strength Parameters Of Coalsupporting

confidence: 67%

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

Gong

2023

Minerals

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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.

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Section: Strength Parameters Of Coalsupporting

confidence: 67%

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

Gong

2023

Minerals

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“…Considering the effect of dynamic disturbance on the coal body of the isolated working face by mining activities Mathematical Problems in Engineering 5 [32,33], introducing the dynamic load coefficient k, the average stress of the working face is shown in…”

Section: Strike Abutment Pressure Distribution Characteristicsmentioning

confidence: 99%

Mechanism and Safety Mining Technology of Overall Instability-Induced Rockbursts of Multi-Coal Seam Spatially Isolated Working Face

Sun

Zhu

Jiang

et al. 2022

Mathematical Problems in Engineering

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The isolated working face has always been the hardest hit area for the occurrence of rockburst, and the spatially isolated working face with multiple coal seams is often easily overlooked due to its hidden nature, which leads to the occurrence of rockburst accidents. This paper takes the Liuhuanggou coal mine (9–15) 08 isolated working face as the engineering background, used field research, theoretical analysis, numerical simulation, and field monitoring, investigated the coal body stress evolution law during mining, and revealed the overall instability rockburst mechanism of the working face and deduced the limit advance distance when the working face was in a state of boundary instability. The research results show the following: (1) with the increase of advancement, the overlying strata on the working face are dynamically transformed from the “C” spatial structure with hollowing on both sides to the “θ” spatial structure with coal body support in the middle; (2) when the dynamic load stress on the coal body of the working face exceeds 1.5 times its integrated compressive strength, there is a risk of overall instability rockburst; (3) when the working face advances to 430 m from the open cutting, the superimposed stress on the coal body exceeds its comprehensive compressive strength and reaches a critical instability state, which is verified by numerical simulation. Based on the analysis of the mechanics and mechanism of the overall instability rockburst of the working face, this paper proposes a set of targeted safe mining solutions: (1) The joint monitoring system of microseism-stress-drilling cutting is adopted to monitor and warn the dangerous rockburst areas. (2) The “rockburst-gas” drilling technique is used to unload the pressure on both sides of the working face and the coal wall. (3) The mining speed shall not exceed 3.2 m/d when the working face is mined before 350 m, and shall not exceed 2.4 m/d when the working face enters the influence area of mined-out LW(4-5)02 (350∼550 m). The microseismic monitoring results and field practice confirmed the reasonableness and effectiveness of the safe mining technology plan.

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“…The results showed that the uniaxial compressive strength, tensile strength, and fracture toughness of gas-containing coal decreased with the increase in initial gas pressure. Currently, most of the studies on the mechanical properties of gas-containing coals are inclined to static mechanics, but in the mining of coal resources, artificial disturbances such as fracture of the roof slab overlying the mining area and rock blasting will produce apparent dynamic phenomena. − The coal body, in this case, will be subjected to dynamic loads along with tectonic stresses and pore pressure in the coal body. When coal/rock is subjected to the multifield coupling effect of underground stress, gas pressure, and quarry disturbance stress, it is easy to trigger the occurrence of disasters such as rock burst or coal and gas outburst.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Effect of Gas Pressure on the Pore Structure and Dynamic Mechanical Properties of Coal

Gao,

Xue,

et al. 2024

ACS Omega

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Understanding the effect of gas pressure on coal pore structure and dynamic mechanical properties can better guide the accurate monitoring of stress and gas in gas-containing coal seams in coal mines and efficiently prevent and control coal/rockgas composite dynamic hazards. In this study, the characterization of the pore structure of the coal body under different gas pressures and three-dimensional impact compression tests were carried out. The findings demonstrate that when the axial static load and confining pressure are fixed, the gas pressure determines the amount of gas adsorbed by the coal samples and its pore structure changes. The effect of gas pressure on the pore structure of the micropores is not obvious, but it has an obvious dilatation effect on the pore structure of the macropores. Within the range of conditions and gas pressures studied in this paper, gas-containing coals' dynamic compressive strength and failure strain decrease linearly with increasing gas pressure. The average dynamic strength deterioration rate of gas-containing coals increases linearly with an increase of gas pressure, which plays a deteriorating role in the dynamic mechanical properties of coal bodies. When the gas pressure increases from 0.7 to 2.8 MPa, the radius of the macropores inside the gas-containing coal increases 0.63 times, and the increased pores and cracks produce a stress concentration effect around the pores and cracks and the shorter time required for instability damage of the coal samples to occur when subjected to dynamic loading. The research results improve the basic theory of gas-containing coal dynamics and provide a theoretical basis for the mine coal/rock-gas composite dynamics disaster.

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Mechanical Properties of Roof Rocks under Superimposed Static and Dynamic Loads with Medium Strain Rates in Coal Mines

Cited by 9 publications

References 51 publications

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

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

Mechanism and Safety Mining Technology of Overall Instability-Induced Rockbursts of Multi-Coal Seam Spatially Isolated Working Face

Experimental Study on the Effect of Gas Pressure on the Pore Structure and Dynamic Mechanical Properties of Coal

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