Tunnelling outburst potential affected by mechanical properties of coal seam

Yang, Wei; Lu, Changzheng; Lin, Baiquan; Jian-guo, Zhang; Lin, Minghua; Wang, Hao

doi:10.1016/j.tust.2018.09.035

Cited by 42 publications

(10 citation statements)

References 33 publications

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“…Gas pressure is positively correlated with the intensity of coal and outburst. The mechanical properties of coals are negatively correlated with the intensity of coal and outburst 36–40 . Therefore, the new method plays an important role in the prevention and control of coal and gas outburst.…”

Section: Discussion Of Engineering Applicationmentioning

confidence: 99%

Freezing method for rock cross-cut coal uncovering I: Mechanical properties of a frozen coal seam for preventing outburst

Yue

Wang

et al. 2019

Sci Rep

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A comprehensive technology is proposed to realize fast and safe rock cross-cut coal uncovering (RCCCU) based on artificial freezing engineering method. This comprehensive technology includes four steps, namely, drilling a borehole, wetting the coal body by water injection, gas drainage and freezing the coal seam by liquid nitrogen injection. In this paper, the compressive strength, tensile strength and shear strength of frozen coal specimens are tested to obtain the mechanical parameters of the specimen. Then, for RCCCU under freezing temperatures, the outburst prevention effects are calculated and quantitatively analysed with regard to three aspects, namely, the enhancement of coal the mechanical properties, the reduction in the coefficient of outburst hazard (COH) in the distressed zone and the reduction in the interfacial elastic energy ratio (IEER) between the coal seam and the roof/floor. The results show that a considerable improvement in the mechanical properties of frozen coal and that the coal mechanical parameters, such as the compressive strength and the tensile strength, increase linearly with decreasing temperature. The coefficient of outburst hazard in the distressed zone decreases rapidly and drops from above 0.8 to below 0.3. The interfacial elastic energy ratio is greatly reduced from dozens of times of that of the roof/floor before freezing to several times of that of the roof/floor after freezing, which effectively weakens the sudden change of the elastic energy at the coal-rock interface.

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Section: Discussion Of Engineering Applicationmentioning

confidence: 99%

Freezing method for rock cross-cut coal uncovering I: Mechanical properties of a frozen coal seam for preventing outburst

Yue

Wang

et al. 2019

Sci Rep

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“…When the crushed coal is exposed due to failure and the surrounding intact coal is broken as a result of mining activities, an outburst would occur with a high gas pressure and a rapid coal ejection. The dynamic theory (Yang et al, 2019) states that the mining-induced stress reduces the strength of the gas-filled coal, forming a tendency for coal and gas outburst. The multiple-factor theory (Beamish and Crosdale, 1998) considers the occurrence of the outburst as the result of the combined effects of several factors: gas, stress, coal property and tectonic environment.…”

Section: Introductionmentioning

confidence: 99%

A Testing Apparatus for Gas-Driven Coal and Gas Outbursts and its Application

et al. 2022

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In this study, a multi-physics coal and gas outburst experimental apparatus is developed to allow investigating the gas-driven mechanism behind the disaster caused by coal and gas outbursts in tectonic regions. The apparatus can simulate the coal and gas outbursts under different initial geo-stresses, gas pressures and temperatures. By integrating acoustic emission sensors in the holes on axial platens, acoustic signals from coal samples during the whole test can be monitored. A series of testability experiments were conducted on the developed apparatus to verify its performance. The damage characteristics and outburst occurrence of raw coal under different gas pressures were experimentally studied and that provided a more complete theoretical basis for coal and gas outburst. The degree of fragmentation of coal samples and the mass proportion distributions of the outburst pulverized coal after outbursts under different gas pressures were analyzed, as a reference for exploring the evolutionary characteristics of coal and gas outburst with gas-driven action.

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“…The mining of the upper 2# coal seam had less impact on the bottom 5# coal seam than on 3# and 4# coal seams. Many studies on the response characteristics of permeability under complex stress conditions in multilayer coal seams, including qualitative and quantitative relationships with axial pressure, confining pressure, multi-phrase, and gas pressure, were conducted to clarify the respective mechanisms (Bultreys et al, 2018;Yang et al, 2019). Xie et al (2016) explored the stress field distribution in coal seams with three different mining methods: non-pillar mining, top-coal caving mining, and protective coalseam mining.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Evolution of Fracture Network and Permeability Characteristics of Bituminous Coal Under Repeated Mining Effect

Zhang

Huang

et al. 2021

Nat Resour Res

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In a group of deep coal seams, mining of upper multilayers generates cyclic loading-unloading stresses in bottom layers, improving their permeability and enhancing coalbed methane gas drainage. In this study, the respective repeated mining stress path was introduced into the seepage test. A high-resolution 3D X-ray microscopy imaging system was used for computed tomography scanning of coal samples. The crack characteristics and stress-permeability relationships were analyzed based on the experimental results. It was found that the permeability increased approximately by 5.8 times after the loading-unloading cyclic tests. The fracture volume and rate grew obviously, and the complexity degree of the fracture network increased. The permeability evolution during the test was closely related to stress-strain state of the coal sample with variable response characteristics of axial deviatoric stress, confining pressure, and axial pressure. The realization of different numbers of loading-unloading cycles in the tests revealed similar fracturing effects of the initial and later cycles, whereas the largest fracturing effect was obtained within the effective stress range from 4 to 11 MPa. The mechanical deformation was found to play an important role in the stress-permeability relationship. The crack closure and elastic deformation at low stressstate caused the permeability loss, while crack growth and plastic deformation at high-stress state increased the permeability. The plastic strain significantly grew with the number of loading-unloading cycles, but the fracturing effect of different numbers of cycles in the critical fissure point was nearly the same. The results obtained are considered instrumental in studying the pressure relief and extraction of coalbed methane during upper protective layer mining in coal seam groups.

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Tunnelling outburst potential affected by mechanical properties of coal seam

Cited by 42 publications

References 33 publications

Freezing method for rock cross-cut coal uncovering I: Mechanical properties of a frozen coal seam for preventing outburst

Freezing method for rock cross-cut coal uncovering I: Mechanical properties of a frozen coal seam for preventing outburst

A Testing Apparatus for Gas-Driven Coal and Gas Outbursts and its Application

Experimental Study on Evolution of Fracture Network and Permeability Characteristics of Bituminous Coal Under Repeated Mining Effect

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