Design principles and key technologies of gob side entry retaining by roof pre-fracturing

Yang, Jun; He, Manchao; Cao, Chen

doi:10.1016/j.tust.2019.05.013

Cited by 82 publications

(45 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the high stratum is an HHR, a large lateral cantilever (key block B) is formed. 25 The movement process of key block B determines the stability of the small structure. The high-position structural instability causes the near-field roofs to break.…”

Section: Vwsf To Release Sgpb In the Stopementioning

confidence: 99%

“…[17][18][19] At present, the most commonly used technologies are coal pillar supports, gob-side entry retention, goaf filling, a spatiotemporal coupling fracturing method using a nonexplosive expansion material, water injection to weaken the roof, presplitting blasting, deep hole blasting, energy-cavity blasting, and hydraulic slitting. 2,14,15,[20][21][22][23][24][25][26][27][28] The main ideas can be summarized as follows: (a) maintain the stability of the hard roof and support the stope space; (b) weaken the hard roof and reduce its rock mass strength; and (iii) transfer the stress or release the strain energy to eliminate the source of SGP.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

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.

show abstract

Section: Vwsf To Release Sgpb In the Stopementioning

confidence: 99%

Section: Introductionmentioning

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

View full text Add to dashboard Cite

show abstract

“…After the first weighting, the side roof of the goaf becomes ruptured and then collapses. Relevant studies assumed that the roof is clamped and supported on the coal wall of the working face [17]. However, for the hard roof of the thin coal seam short-wall face, the roof of the coal walls of the goaf undergoes rotational displacement due to the fracture caused by the first weighting, and the roof support condition can be assumed to be two opposite edges that are simply supported.…”

Section: Periodic Fracture Mechanics Model Of the Roofmentioning

confidence: 99%

Periodic Fracture Model and Control of Hard Roof of Thin Coal Seam Short-wall Face: A Case Study of Zhuzhuang Coal Mine

Wang¹,

Shi²,

Gao³

2019

JESTR

View full text Add to dashboard Cite

The periodic fracture of the hard roof above the working face is the key influencing factor of ground pressure management in the underground exploitation of coal mines. A reasonable breaking span is greatly significant to ensure safe and efficient exploitation of coal mines. The hard roof of the short-wall working face is difficult to break during the mining process. Hence, the II646 fully mechanized coalface of the Zhuzhuang Coal Mine in a mining area in Huaibei, China was taken as the engineering background. Based on the theory of elasticity mechanics, an elastic thin-plate mechanical model of short-wall working faces was established, with the condition of two opposite edges simply supported and with one edge clamped and the other edge free (SCSF). The fracture law of hard roof was studied via theoretical analysis and onsite monitoring. Results show that the breaking span of the hard roof of the II646 working face is 80-90 m. The calculation results of the thin plate mechanical model are closer to the actual situation on-site than the calculation results of the traditional cantilever beam model. By performing calculations with maximum tensile stress theory and a bearing load capacity, the reasonable breaking span was 35 m. Based on the results of the theoretical analysis, the roof weakening scheme of the long-hole pre-splitting blasting was proposed for the II646 working face. The field practice results show that, after using deep-hole pre-splitting blasting, the periodic weighting interval and the working resistance of the support are approximately 35 m and less than 40.1 MPa, respectively. Both of these numbers indicate a decrease compared with before the roof weakens, which the periodic weighting interval (90 m) and working resistance of support (greater than 40.1 MPa), thus avoiding support collapse accidents and achieving safe and efficient mining of the short-wall working face. Such results can provide a scientific basis for the hard roof treatment of short-wall, fully mechanized working faces under similar conditions.

show abstract

“…This loss can reach 40% of the mine's recoverable reserves and is the root cause of coal mining losses . After years of research and exploration, by using the theory of “roof cutting shortwall beam”, Academician Manchao proposed the innovative technology of gob‐side entry retaining formed by roof cutting and pressure releasing . With this method, only one roadway needs to be excavated in a mining face, and there is no coal pillar left between the working faces.…”

Section: Introductionmentioning

confidence: 99%

Evolution and application of airflow permeability characteristics of gob in roof cutting and pressure releasing mining method

Chen

Wang

et al. 2020

Energy Science & Engineering

View full text Add to dashboard Cite

Cutting roof and release pressure technology has changed the pressure transmission mode of the roof and the caving characteristics of roof rock, which in turn has changed the permeability evolution of the gob. To obtain the permeability characteristics of the gob for the roof cutting and pressure releasing mining method, a mathematical model for the gob voidage and permeability was established by analyzing the overlying strata movement law and the lateral stress variation in the gob. The airflow migration law of haulage roadway 12 201 in Halagou coal mine was studied using Fluent software and an established mathematical model. The main conclusions obtained are as follows: The overburden pressure and lateral stress in the gob gradually increase with the advancement of the working face; along the direction of the retaining roadway, there are two roadway windflows entering the critical zones (the 22-100 m and 390-398 m sections). The inflow at these two sections accounted for 59% of the total air inflow, of which the most critical is the 28-53 m section, which accounts for 43% of the total air inflow in the two severe air leakage sections. The findings of this work provide a theoretical basis for the implementation of antileakage technology in the gob under the roof cutting and pressure releasing mining method and help reduce the risk of spontaneous combustion in the gob. K E Y W O R D Scaving characteristics of roof rock, cutting roof and release pressure, gob, voidage and permeability model 2074 |

show abstract

Design principles and key technologies of gob side entry retaining by roof pre-fracturing

Cited by 82 publications

References 23 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

Periodic Fracture Model and Control of Hard Roof of Thin Coal Seam Short-wall Face: A Case Study of Zhuzhuang Coal Mine

Evolution and application of airflow permeability characteristics of gob in roof cutting and pressure releasing mining method

Contact Info

Product

Resources

About