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Modeling behaviors of a coal pillar rib using the progressive S-shaped yield criterion

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 484-492页

作者： Sankhaneel Sinha Gabriel Walton Colorado School of Mines GoldenCO80401USA

Spalling of pillar ribs has been a major hazard in the mining industry for *** the absence of rib support guidelines,accidents have continued to occur in recent *** effective support guidelines requires a complete understanding of complex pillar damage *** models represent a convenient tool for analyzing this problem,but the behavior of such models is dependent of the choice of the constitutive *** this study,a recently proposed constitutive model was used to simulate the rib fracturing process in a longwall chain pillar at West Cliff *** calibration,the model was able to capture the rib displacement profiles for multiple locations of the longwall face and the stress evolution 4 m into the *** rib bolts in the model were found to be yielding over 60% of their length under the headgate loading *** model also predicted a steady damage accumulation in the rib for certain face locations,which is consistent with the description of the rib at the *** was localized along the upper part of the pillar and underscored the role that the dirt band played in controlling rib deterioration at the *** ability of the numerical model to replicate field measurements provides confidence in the capabilities of the new constitutive ***,the need of using multi-point calibration is highlighted by comparing the results of the calibrated model to an alternative model calibrated to a smaller amount of data.

关键词： S-shaped yield criterion coal pillar Back-analysis Numerical modeling

Focal mechanism caused by fracture or burst of a coal pillar

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Journal of China University of Mining and Technology 2008年第2期18卷 153-158页

作者： CAO An-ye DOU Lin-ming CHEN Guo-xiang GONG Si-yuan WANG Yu-gang LI Zhi-hua State Key Laboratory of coal Resource and Mine Safety China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

As a regional, real-time and dynamic method, microseismic monitoring technology is quite an appropriate technology for forecasting geological hazards, such as rock bursts, mine tremors, coal and gas outbursts and can even be used to prevent or at least reduce these disasters. The study of the focal mechanisms of different seismic sources is the prerequisite and basis for forecasting rock burst by microseismic monitoring technology. Based on the analysis on the mechanism and fracture course of coal pillars where rock bursts occur mostly, the equivalent point source model of the seismicity caused by a coal pillar was created. Given the model, the seismic displacement equation of a coal pillar was analyzed and the seismic mechanism was pointed out by seismic wave theory. The course of the fracture of the coal pillar was simulated closely in the laboratory and the equivalent microseismic signals of the fractures of the coal pillar were acquired using a TDS-6 experimental system. The results show that, by the pressure and friction of a medium near the seismic source, both a compression wave and a shear wave will be emitted and shear fracture will be induced at the moment of breakage. The results can be used to provide an academic basis to forecast and prevent rock bursts or tremors in a coal pillar.

关键词： coal pillar rock burst microseismicity fracture focal mechanism point source model

Characteristics of stress distribution in floor strata and control of roadway stability under coal pillars

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Mining Science and Technology 2011年第2期21卷 243-247页

作者： Tongqiang Xiao Bai Jianbiao Xu Lei Zhang Xuebin State Key Laboratory of coal Resources and Safe Mining China University of Mining ＆ Technology Xuzhou 221008 China School of Mines China University of Mining ＆ Technology Xuzhou 221008 China coal Industry Jinan Design Institute Ltd. Jinan 250031 China

Given the difficulties encountered in roadway support under coal pillars,we studied the characteristics of stress distribution and their effect on roadway stability,using theoretical analysis and numerical *** results show that,under a coal pillar,vertical stress in a floor stratum increases while horizontal stress *** conclude that the increased difference between vertical and horizontal stress is an important reason for deformation of the surrounding rock and failures of roadways under coal *** on this,we propose control technologies of the surrounding rock of a roadway under a coal pillar,such as high strength and high pre-stressed bolt support,cable reinforcement support single hydraulic prop with beam support and reinforcement by grouting of the surrounding rock,which have been successfully applied in a stability control project of a roadway under a coal pillar.

关键词： Close-distance seams coal pillar Stress distribution Roadway layout Surrounding rock control

FUZZY FAILURE ANALYSIS OF coal pillarS FOR SUBSIDENCE CONTROL

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Journal of coal Science & Engineering(China) 2000年第1期6卷 19-22页

作者：张玉卓王明立 China coal Research Institute Beijing

Randomness and fuzziness involved in rock failure analysis are discussed in the present *** stochastic process is introduced to simulate pillar/strata deformation *** shows that the evolution from damage to failure of the rock materials under complex stress environments conforms to diffusion *** pillar strength is analyzed using fuzzy failure analysis in two coal mines.

关键词： coal pillar subsidence control fuzzy failure analysis

A review of mechanism and prevention technologies of coal bumps in China

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 180-194页

作者： Yaodong Jiang Yixin Zhao Hongwei Wang Jie Zhu School of Mechanics and Civil Engineering China University of Mining and Technology Beijing 100083 China State Key Laboratory of coal Resources and Safe Mining China University of Mining and Technology Beijing 100083 China School of Resources and Safety Engineering China University of Mining and Technology Beijing 100083 China

coal bump refers to a sudden catastrophic failure of coal seam and usually can cause serious damages to underground mining facilities and staff. In this circumstance, this paper focuses on the recent achievements in the mechanism and prevention techniques of coal bumps over the past five years in *** on theoretical analysis, laboratory experiment, numerical simulation and field test, the characteristics of coal bumps occurrence in China's coal mines were described, and the difference between coal bumps and rockbursts was also discussed. In addition, three categories of coal bumps induced by'material failure' were introduced, i.e. hard roof, floor strata and tectonic structures, in which the mechanism of coal bumps induced by geological structures was analyzed. This involves the bump liability and microstructure effects on bump-prone coal failure, the mechanism of coal bumps in response to fault reactivation, island face mining or hard roof failure. Next, the achievements in the monitoring and controlling methods of coal bumps were reviewed. These methods involve the incorporated prediction system of micro-seismicity and mining-induced pressure, the distributed micro-seismic monitoring system, energy absorption support system, bolts with constant resistance and large elongation,and the 'multi-stage' high-performance support. Finally, an optimal mining design is desirable for the purpose of coal bump mitigation.

关键词： coal bumps Tectonic structure coal pillar Monitoring system coal bumps prevention technology

A physical model study of surrounding rock failure near a fault under the influence of footwall coal mining

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International Journal of coal Science & Technology 2021年第4期8卷 626-640页

作者： Shukun Zhang Lu Lu Ziming Wang Shuda Wang School of City and Architecture Engineering Zaozhuang UniversityZaozhuang 277160ShandongChina School of Civil Engineering Liaoning Technical UniversityFuxin 123000LiaoningChina

A study of the deformation of the surrounding rock and coal pillars near a fault under the influence of mining is conducted on a physical model for the design of coal pillars to support and maintain the roofs of adjacent fault *** research is based on the 15101 mining face in the Baiyangling coal Mine,Shanxi,China,and uses simulation tests similar to digital speckle test technology to analyse the displacement,strain and vertical stress fields of surrounding rocks near faults to determine the influence of the coal pillar *** results are as *** surrounding rock of the roadway roof fails to form a balance hinge for the massive rock *** vertical displacement,vertical strain and other deformation of the surrounding rock near the fault increase steeply as the coal pillar width *** steep increase in deformation corresponds to a coal pillar width of 10 *** the coal pillar width is 7.5 m,the pressure on the surrounding rock near the footwall of the fault suddenly increases,while the pressure on the hanging wall near the fault increases by only 0.35 *** stress of the rock mass of the hanging wall is not completely shielded by the fault,and part of the load disturbance is still transmitted to the hanging wall via *** width of the fault coal pillars at the 15101 working face is determined to be 7.5 m,and the monitoring data verify the rationality of the fault coal pillars.

关键词： Fault Mining roadway Surrounding rock coal pillar Physical model

MODELING OF OVERBURDEN FAILURE UNDER THE CONDITION OF MINING TWO CLOSE-RANGE SEAMS USING ROOM-AND-pillar ANDLONGWALL MINING

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Journal of coal Science & Engineering(China) 2000年第1期6卷 10-13页

作者：张玉卓王明立 China coal Research Institute Beijing100013

In this paper, the effect of the remaining coal pillars in a room and pillar section on the long wall face in the lower coal bed are tested by using equivalent material models. The failure laws of the overburden under coal pillars are discussed. A phenomenon of sub weighting has been observed when long wall face is in process under the remaining pillars in room and pillar mining section. It is concluded that, because coal pillars underwent a course of the stress increasing before they were fully destroyed, the existence of the coal pillars would shorten the distance of periodical weighting of the main roof in the long wall face. Based on this, the characteristic equations of the overburden movement under coal pillars are presented.

关键词： coal pillar overburden failure sub weighting