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Statistical properties of seismic foreshocks and aftershocks associated with longwall mining:Implications from the Epidemic Type Aftershock Sequence model

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第12期16卷 4878-4894页

作者： Xu Li Guangyao Si Bobo Shi Wenzhuo Cao Wu Cai Joung Oh Ismet Canbulat School of Minerals and Energy Resources Engineering University of New South WalesSydneyNSW2052Australia Key Laboratory of Gas and Fire Control for Coal Mines(China University of mining and Technology) Ministry of EducationXuzhou221116China Department of Earth Sciences Utrecht University3584 CSUtrechtthe Netherlands State Key Laboratory of Coal Resources and Safe mining School of MinesChina University of Mining and TechnologyXuzhou221116China

The control and management of mining-induced seismic hazards have attracted ever-rising attention,especially in underground longwall coal mines,where continuous mining activities dynamically alter the stress states and induce seismic *** this work,the Epidemic Type Aftershock Sequence(ETAS)model was applied to formulate the aftershock catalogue of mining-induced seismicity and investigate the formation of event triggering associated with longwall *** conventional Baiesi and Paczuski method(2004)was used to separate longwall mining-induced seismic events into triggered and nontriggered *** latter catalogue contains both non-triggering(NT)-isolated events that do not trigger subsequent events and NT-parent events of the former *** properties of triggered events were analysed spatially and *** temporal triggering sequence follows the Omori-Utsu law,where the temporal decay of aftershocks is influenced by the magnitude of NT-parent events in mining-induced *** spatial distribution of aftershocks follows an inverted U-shaped relationship with distance to their corresponding NT-parent *** quantitative forecasting of triggered events was performed based on the nonhomogeneous Poisson distribution,which achieved a good consistency with their NT-parent *** the non-triggered catalogue,NT-isolated events are concentrated ahead of NT-parent events,potentially acting as foreshocks for the latter.

关键词： Event triggering Seismicity longwall mining Foreshocks Aftershocks

An influence function method based subsidence prediction program for longwall mining operations in inclined coal seams

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mining Science and Technology 2009年第5期19卷 592-598页

作者： LUO Yi CHENG Jian-wei Department of mining Engineering West Virginia University Morgantown WV USA

The distribution of the final surface subsidence basin induced by longwall operations in inclined coal seam could be significantly different from that in flat coal seam and demands special prediction methods. Though many empirical prediction methods have been developed, these methods are inflexible for varying geological and mining conditions. An influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, significant modifications have been made to the original Knothe function to produce an asymmetrical influence function. The empirical equations for final subsidence parameters derived from US subsidence data and Chinese empirical values have been incorpo- rated into the mathematical models to improve the prediction accuracy. A corresponding computer program is developed. A number of subsidence cases for longwall mining operations in coal seams with varying inclination angles have been used to demonstrate the applicability of the developed subsidence prediction model.

关键词： subsidence prediction influence function method inclined coal seam longwall mining

Passive seismic velocity tomography on longwall mining panel based on simultaneous iterative reconstructive technique (SIRT)

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Journal of Central South University 2012年第8期19卷 2297-2306页

作者： N.Hosseini K.Oraee K.Shahriar K.Goshtasbi Department of mining Engineering South Tehran BranchIslamic Azad UniversityTehran 17776-13651Iran Department of Management University of StirlingStirling FK94LAUK Department of mining and Metallurgical Engineering Amirkabir University of TechnologyTehran 15916-34311Iran Department of mining Engineering Tarbiat Modares UniversityTehran 14115-111Iran

mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion is used to deduce the stress redistribution around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method （BEM） was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the longwall panel. In velocity tomograms, the main zones of the stress redistribution arotmd the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the longwall mining panel continuously and subsequently to improve safety of mining operations.

关键词： longwall mining passive seismic velocity tomography simultaneous iterative reconstructive technique (SIRT) boundary element method stress redistribution ground control

New development of longwall mining equipment based on automation and intelligent technology for thin seam coal

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Journal of Coal Science & Engineering(China) 2013年第1期19卷 97-103页

作者： Guo-fa WANG China Coal Technology and Engineering Group Beijing 100013 China

The paper introduced complete sets of automatic equipment and technology used in thin seam coal face, and proposed the comprehensive mechanization and automation of safe and high efficiency mining models based on the thin seam drum shearer. The key technology of short length and high power thin seam drum shearer, and new type roof support with big extension ratio and plate canopy were introduced. The new research achievement on automatic control system of complete sets of equipment for the thin seam coal, which composed of electronic-hydraulic system, compact thin seam roof supports, high effective shearer with intelligent control system, and characterized by automatical follow-up and remote control technology, was described in this paper..

关键词： longwall mining thin coal seam complete sets of equipment automatic system intelligent system

An improved influence function method for predicting subsidence caused by longwall mining operations in inclined coal seams

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International Journal of Coal Science & Technology 2015年第3期2卷 163-169页

作者： Yi Luo Department of mining Engineering West VirginiaUniversity Morgantown WV USA

Prediction of surface subsidence caused by longwall mining operation in inclined coal seams is often very challenging. The existing empirical prediction methods are inflexible for varying geological and mining conditions. An improved influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, the original Knothe function has been transformed to produce a continuous and asymmetrical subsidence influence function. The empirical equations for final subsidence parameters derived from col- lected longwall subsidence data have been incorporated into the mathematical models to improve the prediction accuracy. A number of demonstration cases for longwall mining operations in coal seams with varying inclination angles, depths and panel widths have been used to verify the applicability of the new subsidence prediction model.

关键词： Subsidence prediction Influence function method Inclined coal seam longwall mining

Study on effects of longwall mining on the underground water

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Journal of Coal Science & Engineering(China) 2007年第2期13卷 126-130页

作者：郭文兵 Syd S．Peng School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo 454000 Department 0f mining Engineering West Virginia UniversityMorgantown 26505China

It is very important for secure mining under water bodies to study the effects of Iongwall mining on the underground water. In order to study this problem, piezometers for monitoring underground water levels were established in an American coalmine. Large amounts of pre-mining and post-mining monitoring data were collected. Based on the data the effects of Iongwall mining on the underground water was studied. The results demonstrate that when the piezometer monitoring wells have an interburden thickness less than 72.7 m, the groundwater level decreases immediately to immeasurable levels and go dry after undermining. The height of the fractured zone in is 72.7-85.3 m in this geological and mining conditions. The results also show that the calculated value of fractured zone by the empirical formulae used in China is smaller than the actual results. Therefore, it is not always safe to use them in analysis of mining under water bodies.

关键词： longwall mining aquifer piezometer monitoring wells mining under waterbodies

Assessment of Relationship of Some Causal Factors Associated with Productivity of longwall mining Using Structured Equation Modeling

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Journal of Minerals and Materials Characterization and Engineering 2021年第4期9卷 375-389页

作者： Sidharth Talan Ashis Bhattacherjee Trafigura Mumbai India mining Engineering Department Indian Institute of Technology Kharagpur India

Enhancement of productivity optimization is steadily gaining the priority in mining companies especially in the underground coal mining industry which faces a daunting task to balance marginal profit generation with a comparatively high cost of production, volatile market price and rapid grade variation. This paper is aimed to analyze some of the causal factors both technical and site specific which are directly or indirectly impacting the productivity of the longwall coal mining system such as downtime of equipment system in longwall panel, overloading of conveyors and bin, preventive maintenance, gas management practices and injury severity rate. Structured Equation Modelling (SEM) was used to study the causal relationships between the above-mentioned factors and mine productivity. The equipment considered for analysis included shearer, armored face conveyor, crusher, bridge stage loader, chock supports, main gate drive, gate conveyor, hydraulic pumps and crusher. SEM was applied to relate the correlations existing among these causal variables in order to assess their direct or indirect impact on mining productivity. Based on the data extracted over a period of 10 months which included the extraction of 2 longwall panels, the study revealed a significant negative causal relationship between injury severity rate (p < 0.01) and equipment downtime (p = 0.001), with mine productivity. However, preventive maintenance delay time, gas management delay time and conveyor overloading delay time were found to have an insignificant direct influence on mine productivity but indirectly modify it through a significant mediator relationship with equipment downtime. This information would assist mine management to take proper preventive measures.

关键词： Structured Equation Modelling longwall mining Operational Equipment Productivity

Numerical Study on Effect of longwall mining on Stability of Main Roadway under Weak Ground Conditions in Indonesia

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Journal of Geological Resource and Engineering 2017年第3期5卷 93-104页

作者： Phanthoudeth Pongpanya Takashi Sasaoka Hideki Shimada Akihiro Hamanaka Sugeng Wahyudi Department of Earth Resources Engineering Faculty of Engineering Kyushu University 744 Motooka Nishi-ku Fukuoka-shi819-0395 Japan Department of mining Engineering Faculty of Engineering National University of Laos Lao-Thai Friendship Road Vientiane3166 Lao PDR

The purpose of this research is to study the effect of longwall mining on the stability of main roadway in the underground coal mine. The PT GDM （Gerbang Daya Mandiri） underground coal mine in Indonesia, where the rocks are weak, was selected as a representative study site. To accomplish the objective of the research, the finite difference code software FLAC3D was used as a tool for the numerical simulations. The longwall mining of several panel and barrier pillar widths at various depths was simulated and discussed. Based on the simulation results, it indicates that the effect of coal panel extraction on the main roadway stability depends on the width of panel and barrier pillar. The greatest effect occurs when the large panel width and the small barrier pillar width are applied, whereas the smallest effect happens when the narrow panel width and the large barrier pillar width are adopted. In this paper, therefore, to maintain the stability of the main roadway with the aim of maximizing the coal recovery, the appropriate size of panel and barrier pillar width is proposed for each mining depth for this underground coal mine.

关键词： FLAC3D longwall mining numerical simulation weak ground conditions roadway stability.

Characteristics of evolution of mining-induced stress field in the longwall panel:insights from physical modeling

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International Journal of Coal Science & Technology 2021年第5期8卷 938-955页

作者： Jinfu Lou Fuqiang Gao Jinghe Yang Yanfang Ren Jianzhong Li Xiaoqing Wang Lei Yang Coal mining Research Institute China Coal Technology and Engineering Group Co.Ltd.Beijing 100013China State Key Laboratory of Coal mining and Clean Utilization(China Coal Research Institute) Beijing 100013China

The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of *** laboratory experiments have been conducted to investigate the stress *** study investigated its evolution by constructing a large-scale physical model according to the in situ conditions of the longwall *** analysis was used to reveal the mechanism of stress distribution in the *** modelling results showed that:(1)The major principal stress field is arch-shaped,and the strata overlying both the solid zones and gob constitute a series of coordinated load-bearing *** stress increasing zone is like a macro stress *** stress is especially concentrated on both shoulders of the arch-shaped *** stress concentration of the solid zone in front of the gob is higher than the rear solid zone.(2)The characteristics of the vertical stress field in different regions are significantly *** decreases in the zone above the gob and increases in solid zones on both sides of *** mechanical analysis show that for a given stratum,the trajectories of principal stress are arch-shaped or inverselyarched,referred to as the‘‘principal stress arch’’,irrespective of its initial breaking or periodic breaking,and determines the fracture *** is,the trajectories of tensile principal stress are inversely arched before the first breaking of the strata,and cause the breaking lines to resemble an inverted *** case of periodic breaking,the breaking line forms an obtuse angle with the advancing direction of the *** agreement was obtained between the results of physical modeling and the theoretical analysis.

关键词： longwall mining mining-induced stress field Physical modeling Principal stress trajectory Strain brick