Field Investigation of a Roof Fall Accident and Large Roadway Deformation Under Geologically Complex Conditions in an Underground Coal Mine

Wang, Hongwei; Xue, Sheng; Jiang, Yaodong; Deng, Dean; Shi, Shuyuan; Zhang, Dengqiang

doi:10.1007/s00603-018-1425-1

Cited by 54 publications

(23 citation statements)

References 24 publications

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“…where K g is the load transfer coefficient. According to the stress equilibrium theory of loosened material, 49 the width s of the stress limit equilibrium zone and seam interface stress σ y are, 14 respectively.…”

Section: Criterion For the Hhr Supported By Caved Rocksmentioning

confidence: 99%

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Pan

Xia

et al. 2020

Energy Science & Engineering

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Traditional methods of controlling hard roofs have a limited scope of action and cannot effectively release the strong ground pressure behavior (SGPB) induced by high-position hard roofs (HHRs) in extra-thick coal seam mining (ETCSM). Thus, an innovative control technology of fracturing HHRs by vertical-well stratified fracturing (VWSF) has been proposed. However, the key parameters of VWSF, namely fracturing horizon and fracturing thickness of HHRs, which have a significant influence on stope stability, remain uncertain. In this study, a mechanical model of the "coal wall-hydraulic support-gangue" support system is established by considering the effective loading acting on HHRs, through which modified expressions for the periodic breaking span and impact kinetic energy of the stope are deduced. Based on the self-bearing of bulking rocks, the stability principle of the surrounding rock, and energy dissipation theories, the criteria for determining the fracturing horizon and thickness of the HHR are obtained. Next, a numerical model of ETCSM, which accounts for the supporting effect of gangue, is constructed in FLAC3D. The support load and energy released by stratum breakage are determined through modeling under various hard roof parameters, thus verifying the correctness of the determination criteria. The results show that the energy released by a hard roof, average support load, and critical support load are positively correlated with thickness, and first increase before declining with respect to an increase in the fracturing horizon.The key parameters for a real coal mine are obtained by theoretical calculations and numerical simulations. A field application demonstrates that the support load and advance roadway deformation can be decreased using the proposed parameterization. This provides theoretical support for determining the key parameters of HHRs for VWSF and facilitates the widespread application of VWSF technology in HHR control. K E Y W O R D Shigh-position hard roofs, microseismic monitoring, mine safety, strong ground pressure behavior, vertical-well stratified fracturing | 2217 PAN et Al.

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Section: Criterion For the Hhr Supported By Caved Rocksmentioning

confidence: 99%

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Pan

Xia

et al. 2020

Energy Science & Engineering

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“…In Chinese coal mines, 70‐80 percent of the annual roadway excavations are developed under the high‐stress conditions which can be attributed to the geological abnormalities, the large burial depth, the strong abutment stresses, or the combination of those factors . The high‐stress conditions often cause large deformation of the roadways, and in some cases, the convergence rate of roadway surfaces may reach up to 100 mm/d; therefore, significant efforts are routinely required to reconstruct the roadways . As a result, the cost of longwall mining is significantly increased and the production of coal is greatly restricted …”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] The high-stress conditions often cause large deformation of the roadways, and in some cases, the convergence rate of roadway surfaces may reach up to 100 mm/d; therefore, significant efforts are routinely required to reconstruct the roadways. 4,5 As a result, the cost of longwall mining is significantly increased and the production of coal is greatly restricted. 1,6 Researchers have developed some techniques to improve the bearing capacities of the surrounding rocks and reduce the convergence of roadways developed under high-stress environment.…”

Section: Introductionmentioning

confidence: 99%

Depressurizing boreholes for mitigating large deformation of the main entry

Wang

Zheng

Shen

et al. 2019

Energy Science & Engineering

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The main entries in longwall coal mine frequently encounter large deformation, depending on the stress environment. Depressurizing boreholes are applicable to reduce the large deformation; however, it is difficult to determine the proper parameters (diameter and spacing) for an effective implementation. This study aims to propose feasible design criteria for the quantification of those parameters. We first developed a rigorous numerical model, for a roadway in Zhangshuanglou coal mine, using the rock mechanical properties determined from extensive laboratory measurements and analyses. We then investigated the dependency of the stress transfer and roadway deformation on the ratio of borehole diameter and spacing (D/R and D/I). The symbols of D, R, and I represented the diameter, row spacing, and interspacing of the boreholes, respectively. We found that (a) D/R has to be between 1:6 and 1:2; and (b) D/I has to be between 1:6 and 1:4, for sufficient depressurization in the surrounding rocks. The optimized borehole diameter and spacing parameters were applied in the field where the deformation of roadway was significantly reduced. Finally, we proposed a criterion to determine those parameters of depressurization boreholes for application in other geological and mining conditions.

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“…Typical tensile bolts are the D bolt, Cone bolt, Roofex bolt, and Constant Resistance Large Deformation bolt [12][13][14][15][16][17][18]. Especially, the Constant Resistance Large Deformation (CRLD) bolt, invented at China University of Mining and Technology Beijing (CUMTB), has the advantages of constant high resistance and large deformation and has been used successfully in some coal mines [17][18][19][20].In recent years, the traditional bolt-mesh-cable support and bolt support for solving the stability problem of surrounding rock in shallow roadways has been shown to have a certain effect, but under complex geological conditions of high stress and mining action, the deformation of surrounding rock in the deep soft rock roadways is seriously large [21][22][23][24][25]. The traditional supporting mechanism theory and traditional support countermeasures cannot effectively reveal and control the large deformation of the surrounding rock in deep roadways [8,26,27].Reasonable support countermeasures should be based on the correct evaluation and analysis of the deformation mechanisms of specific roadways [26].…”

mentioning

confidence: 99%

“…In recent years, the traditional bolt-mesh-cable support and bolt support for solving the stability problem of surrounding rock in shallow roadways has been shown to have a certain effect, but under complex geological conditions of high stress and mining action, the deformation of surrounding rock in the deep soft rock roadways is seriously large [21][22][23][24][25]. The traditional supporting mechanism theory and traditional support countermeasures cannot effectively reveal and control the large deformation of the surrounding rock in deep roadways [8,26,27].…”

mentioning

confidence: 99%

Nonlinear Large Deformation Mechanism and Stability Control of Deep Soft Rock Roadway: A Case Study in China

et al. 2019

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Improving the safety and stability of soft surrounding rock with nonlinear large deformation gives a strong guarantee for the safe mining and sustainable development of deep coal mines. In order to control the nonlinear large deformation of the surrounding rock in a deep soft rock roadway, this paper discusses the nonlinear large deformation mechanism and coupling support countermeasures of a typical engineering application at Xin’an coal mine in Gansu province, China. The series of experiments and theoretical analysis described in this paper reveal the phenomena, properties, and reasons for the nonlinear large deformation of soft surrounding rock in detail. Then, the type of nonlinear large deformation mechanism is determined and transformed from a composite one to a simple one. Based on experimental results and mechanism transformation, a suitable coupling support countermeasure, which contains the Constant Resistance Large Deformation (CRLD) bolt, steel mesh, floor hollow grouting cable, and steel fiber concrete, is proposed to reduce the nonlinear large deformation and the potential risk during mining. The application shows that the coupling support countermeasure can effectively reduce the nonlinear large deformation of the surrounding rock and help to maintain the stability of the deep soft rock roadway at Xin’an coal mine.

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Field Investigation of a Roof Fall Accident and Large Roadway Deformation Under Geologically Complex Conditions in an Underground Coal Mine

Cited by 54 publications

References 24 publications

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Depressurizing boreholes for mitigating large deformation of the main entry

Nonlinear Large Deformation Mechanism and Stability Control of Deep Soft Rock Roadway: A Case Study in China

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