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Estimating shear strength of high-level pillars supported with cemented backfilling using the HoekeBrown strength criterion 被引量:4
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作者 Kaizong Xia Congxin Chen +3 位作者 Xiumin Liu Yue Wang Xuanting Liu Jiahao Yuan 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期454-469,共16页
Deep metal mines are often mined using the high-level pillars with subsequent cementation backfilling(HLSCB)mining method.At the design stage,it is therefore important to have a reasonable method for determining the s... Deep metal mines are often mined using the high-level pillars with subsequent cementation backfilling(HLSCB)mining method.At the design stage,it is therefore important to have a reasonable method for determining the shear strength of the high-level pillars(i.e.cohesion and internal friction angle)when they are supported by cemented backfilling.In this study,a formula was derived for the upper limit of the confining pressure σ3max on a high-level pillar supported by cemented backfilling in a deep metal mine.A new method of estimating the shear strength of such pillars was then proposed based on the Hoek eBrown failure criterion.Our analysis indicates that the horizontal stress σhh acting on the cemented backfill pillar can be simplified by expressing it as a constant value.A reasonable and effective value for σ3max can then be determined.The value of s3max predicted using the proposed method is generally less than 3 MPa.Within this range,the shear strength of the high-level pillar is accurately calculated using the equivalent MohreCoulomb theory.The proposed method can effectively avoid the calculation of inaccurate shear strength values for the high-level pillars when the original HoekeBrown criterion is used in the presence of large confining pressures,i.e.the situation in which the cohesion value is too large and the friction angle is too small can effectively be avoided.The proposed method is applied to a deep metal mine in China that is being excavated using the HLSCB method.The shear strength parameters of the high-level pillars obtained using the proposed method were input in the numerical simulations.The numerical results show that the recommended level heights and sizes of the high-level pillars and rooms in the mine are rational. 展开更多
关键词 Deep metal mines High-level pillars HoekeBrown strength criterion Cemented backfilling Confining pressure Shear strength
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Investigation of stress-induced progressive failure of mine pillars using a Voronoi grain-based breakable block model
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作者 Shili Qiu Shirui Zhang +3 位作者 Quan Jiang Shaojun Li Hao Zhang Qiankuan Wang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第5期713-729,共17页
The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-... The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-rock mine pillars.The influence of the microscopic parameters on the macroscopic mechanical behavior was investigated using laboratory-scale models.The field-scale pillar models(width-to-height,W/H=1,2 and 3)were calibrated based on the empirically predicted stress-strain curves of Creighton mine pillars.The results indicated that as the W/H ratios increased,the VGBBM effectively predicted the transition from strain-softening to pseudo-ductile behavior in pillars,and explicitly captured the separated rock slabs and the V-shaped damage zones on both sides of pillars and conjugate shear bands in core zones of pillars.The volumetric strain field revealed significant compressional deformation in core zones of pillars.While the peak strains of W/H=1 and 2 pillars were relatively consistent,there were significant differences in the strain energy storage and release mechanism.W/H was the primary factor influencing the deformation and strain energy in the pillar core.The friction coefficient of the structural plane was also an important factor affecting the pillar strength and the weakest discontinuity angle.The fracture surface was controlled by the discontinuity angle and the friction coefficient.This study demonstrated the capability of the VGBBM in predicting the strengths and deformation behavior of hard-rock pillars in deep mine design. 展开更多
关键词 pillar strength FDEM Voronoi tessellation SPALLING BULKING
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Pillar effect induced by ultrahigh phosphorous/nitrogen doping enables graphene/MXene film with excellent cycling stability for alkali metal ion storage
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作者 Meng Qin Yiwei Yao +5 位作者 Junjie Mao Chi Chen Kai Zhu Guiling Wang Dianxue Cao Jun Yan 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第6期146-156,I0004,共12页
Graphene's large theoretical surface area and high conductivity make it an attractive anode material for potassium-ion batteries(PIBs).However,its practical application is hindered by small interlayer distance and... Graphene's large theoretical surface area and high conductivity make it an attractive anode material for potassium-ion batteries(PIBs).However,its practical application is hindered by small interlayer distance and long ion transfer distance.Herein,this paper aims to address the issue by introducing MXene through a simple and scalable method for assembling graphene and realizing ultrahigh P doping content.The findings reveal that MXene and P-C bonds have a "pillar effect" on the structure of graphene,and the P-C bond plays a primary role.In addition,N/P co-doping introduces abundant defects,providing more active sites for K^(+) storage and facilitating K^(+) adsorption.As expected,the developed ultrahigh phosphorous/nitrogen co-doped flexible reduced graphene oxide/MXene(NPrGM) electrode exhibits remarkable reversible discharge capacity(554 mA hg^(-1) at 0.05 A g^(-1)),impressive rate capability(178 mA h g^(-1) at 2 A g^(-1)),and robust cyclic stability(0.0005% decay per cycle after 10,000 cycles at 2 A g^(-1)).Furthermore,the assembled activated carbon‖NPrGM potassium-ion hybrid capacitor(PIHC) can deliver an impressive energy density of 131 W h kg^(-1) and stable cycling performance with 98.1% capacitance retention after5000 cycles at 1 A g^(-1).Such a new strategy will effectively promote the practical application of graphene materials in PIBs/PIHCs and open new avenues for the scalable development of flexible films based on two-dimensional materials for potential applications in energy storage,thermal interface,and electromagnetic shielding. 展开更多
关键词 GRAPHENE MXene Phosphorous doping pillar effect Potassium-ion batteries
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Numerical and theoretical study of load transfer behavior during cascading pillar failure
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作者 Hangyu Dong Wancheng Zhu +2 位作者 Leilei Niu Chen Hou Xige Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3014-3033,共20页
To further study the load transfer mechanism of roofemulti-pillarefloor system during cascading pillar failure(CPF),numerical simulation and theoretical analysis were carried out to study the three CPF modes according... To further study the load transfer mechanism of roofemulti-pillarefloor system during cascading pillar failure(CPF),numerical simulation and theoretical analysis were carried out to study the three CPF modes according to the previous experimental study on treble-pillar specimens,e.g.successive failure mode(SFM),domino failure mode(DFM)and compound failure mode(CFM).Based on the finite element code rock failure process analysis(RFPA^(2D)),numerical models of treble-pillar specimen with different mechanical properties were established to reproduce and verify the experimental results of the three CPF modes.Numerical results show that the elastic rebound of roofefloor system induced by pillar instability causes dynamic disturbance to adjacent pillars,resulting in sudden load increases and sudden jump displacement of adjacent pillars.The phenomena of load transfer in the roofemulti-pillarefloor system,as well as the induced accelerated damage behavior in adjacent pillars,were discovered and studied.In addition,based on the catastrophe theory and the proposed mechanical model of treble-pillar specimen edisc spring group system,a potential function that characterizes the evolution characteristics of roof emulti-pillarefloor system was established.The analytical expressions of sudden jump and energy release of treble-pillar specimenedisc spring group system of the three CPF modes were derived according to the potential function.The numerical and theoretical results show good agreement with the experimental results.This study further reveals the physical essence of load transfer during CPF of roof emulti-pillarefloor system,which provides references for mine design,construction and disaster prevention. 展开更多
关键词 Cascading pillar failure(CPF) Load transfer Multi-pillar Numerical simulation
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Pillar植入系统联合鼻部手术治疗OSAHS 38例疗效分析 被引量:4
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作者 邹帆 邝韶景 +1 位作者 高明华 李明红 《重庆医学》 CAS CSCD 北大核心 2010年第8期917-918,926,共3页
目的探讨Pillar植入系统联合鼻部手术治疗阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的效果。方法选取2006年7至2008年11月本科OSAHS患者38例,38例均同期行Pillar植入系统治疗和鼻部手术,术前及术后6个月均行多导睡眠呼吸监测(polysomnogra... 目的探讨Pillar植入系统联合鼻部手术治疗阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的效果。方法选取2006年7至2008年11月本科OSAHS患者38例,38例均同期行Pillar植入系统治疗和鼻部手术,术前及术后6个月均行多导睡眠呼吸监测(polysomnography,PSG),对术前及术后的PSG结果(包括AHI、LSaO2)进行统计学分析。结果术后6个月进行PSG监测,治愈10例,好转17例,减轻7例,无效4例,总有效率达89.5%;所有患者无手术并发症发生。结论Pillar植入系统联合鼻部手术治疗单纯型鼾症(primary snoring,PS)及轻-中度OSAHS可取得良好效果。 展开更多
关键词 睡眠呼吸暂停低通气综合征 阻塞性 鼻疾病 pillar植入系统 鼻部手术
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Experimental studies on pillar failure characteristics based on acoustic emission location technique 被引量:11
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作者 徐帅 刘建坡 +3 位作者 徐世达 魏炯 黄文柏 东龙宾 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第11期2792-2798,共7页
Acoustic emission (AE) technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A ... Acoustic emission (AE) technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A combined AE location algorithm was developed based on the Least square algorithm and Geiger location algorithm. The pencil break test results show that the location precision can meet the demand of microcrack monitoring. The 3D location of AE events can directly reflect the process of initiation, propagation and evolutionary of microcracks. During the loading process, stress is much likely concentrated on the area between pillar and roof of the specimen, where belongs to danger zone of macroscopic failure. When rock reaches its plastic deformation stage, AE events begin to decrease, which indicates that AE quiet period can be seen as precursor characteristic of rock failure. 展开更多
关键词 rock damage mechanism pillar specimen failure characteristics temporal-spatial evolution microracks acousticemission location algorithm quiet period
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Predicting pillar stability for underground mine using Fisher discriminant analysis and SVM methods 被引量:16
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作者 周健 李夕兵 +2 位作者 史秀志 魏威 吴帮标 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第12期2734-2743,共10页
The purpose of this study is to apply some statistical and soft computing methods such as Fisher discriminant analysis (FDA) and support vector machines (SVMs) methodology to the determination of pillar stability ... The purpose of this study is to apply some statistical and soft computing methods such as Fisher discriminant analysis (FDA) and support vector machines (SVMs) methodology to the determination of pillar stability for underground mines selected from various coal and stone mines by using some index and mechanical properties, including the width, the height, the ratio of the pillar width to its height, the uniaxial compressive strength of the rock and pillar stress. The study includes four main stages: sampling, testing, modeling and assessment of the model performances. During the modeling stage, two pillar stability prediction models were investigated with FDA and SVMs methodology based on the statistical learning theory. After using 40 sets of measured data in various mines in the world for training and testing, the model was applied to other 6 data for validating the trained proposed models. The prediction results of SVMs were compared with those of FDA as well as the measured field values. The general performance of models developed in this study is close; however, the SVMs exhibit the best performance considering the performance index with the correct classification rate Prs by re-substitution method and Pcv by cross validation method. The results show that the SVMs approach has the potential to be a reliable and practical tool for determination of pillar stability for underground mines. 展开更多
关键词 underground mine pillar stability Fisher discriminant analysis (FDA) support vector machines (SVMs) PREDICTION
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微创经椎弓根Pillar植入治疗胸腰椎压缩性骨折疗效及相关并发症分析 被引量:3
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作者 张爱梁 何双华 +7 位作者 丁亮华 包欣南 胡新宇 王能 凌为其 张乃东 黄智慧 王轩 《南京医科大学学报(自然科学版)》 CAS CSCD 北大核心 2014年第11期1568-1570,共3页
目的 :探讨经椎弓根pillar植入治疗胸腰椎压缩性骨折的临床效果及相关并发症。方法 :回顾分析2010年1月~2013年4月采用微创经椎弓根pillar置入治疗胸腰椎压缩性骨折患者27例的临床疗效。手术前后进行疼痛强度视觉模拟评分(visual an... 目的 :探讨经椎弓根pillar植入治疗胸腰椎压缩性骨折的临床效果及相关并发症。方法 :回顾分析2010年1月~2013年4月采用微创经椎弓根pillar置入治疗胸腰椎压缩性骨折患者27例的临床疗效。手术前后进行疼痛强度视觉模拟评分(visual analogue scale,VAS)、Oswestry功能障碍指数(Oswestry disability index,ODI)、伤椎前缘高度比值、矢状面指数(伤椎前缘高度/伤椎后缘高度×100%)、伤椎Cobb′s角。结果:27例患者共植入54枚椎体支柱块,均获得6~26个月的随访,平均手术时间为(47.6±8.5)min,平均术中失血量(28.4±12.3)ml。术后CT证实17例患者椎弓根皮质有破裂,其中外侧皮质破裂15例,内侧皮质破裂2例,其中1例患者因内侧壁破裂引起下肢神经症状,经治疗后缓解。术后1周及末次随访时VAS评分、ODI值、椎体前缘高度比值、矢状面指数值及伤椎Cobb′s角与术前比较差异均具有统计学意义(P〈0.05),而术后1周与末次随访时比较差异无统计学意义(P〉0.05),椎体支柱块未发生移位或塌陷。结论:微创经椎弓根pillar置入是治疗胸腰椎压缩骨折一种安全、有效、可行的方法,严格掌握手术适应证、术中规范操作可降低并发症的发生。 展开更多
关键词 胸腰椎骨折 pillar 疗效 并发症
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CUSP CATASTROPHE MODEL OF INSTABILITY OF PILLAR IN ASYMMETRIC MINING 被引量:20
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作者 李江腾 曹平 《应用数学和力学》 EI CSCD 北大核心 2005年第8期1003-1008,共6页
关键词 矿柱 稳定性 势能 尖点突变 非对称开采
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Pillar植入术治疗阻塞性睡眠呼吸暂停综合征病人的观察和护理 被引量:1
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作者 龚穗清 陈秋芳 +4 位作者 陈玉微 吴小琴 毛晓萍 陈少华 张思毅 《护理研究(下旬版)》 2008年第7期1931-1932,共2页
[目的]探讨Pillar植入术治疗阻塞性睡眠呼吸暂停综合征(OSAS)的护理及术后随访。[方法]46例鼾症病人经我导睡眠仪(PSG)监测分为轻至中度OSAS(28例)、重度OSAS(6例)和单纯鼾症(12例)3组,行Pillar植入术,并给予全面的身心护理和健康教育,... [目的]探讨Pillar植入术治疗阻塞性睡眠呼吸暂停综合征(OSAS)的护理及术后随访。[方法]46例鼾症病人经我导睡眠仪(PSG)监测分为轻至中度OSAS(28例)、重度OSAS(6例)和单纯鼾症(12例)3组,行Pillar植入术,并给予全面的身心护理和健康教育,术前及术后1个月和6个月均进行鼾声视觉类比量表(VAS)评分和PSG监测。[结果]术后随访6个月,Pillar植入系统对于轻至中度OSAS病人和单纯鼾症病人打鼾的改善显著,而对于重度OSAS病人疗效较差。28例轻至中度OSAS病人治愈4例,显效10例,有效5例,无效9例,总有效率达67.9%,呼吸紊乱指数(AHI)由术前的每小时17.03次±10.63次到术后6个月降至每小时11.17次±9.52次;6例重度OSAS病人有效1例(1/6),AHI由术前每小时62.93次±9.21次降至每小时55.42次±13.77次,46例病人术后无并发症。[结论]Pillar植入系统对于治疗鼾症可以有效地改善打鼾,对于睡眠呼吸暂停的改善轻至中度OSAS病人的疗效较好,而重度OSAS病人的疗效较差。而做好Pillar手术的护理,可帮助病人顺利完成手术治疗,减轻他们术前的忧虑和术后的痛苦,获得满意效果,提高生活质量。 展开更多
关键词 pillar植入术 阻塞性睡眠呼吸暂停综合征 观察 护理
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Numerical investigation into the effect of backfilling on coal pillar strength in highwall mining 被引量:9
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作者 Mo S. Canbulat I. +3 位作者 Zhang C. Oh J. Shen B. Hagan P. 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2018年第2期281-286,共6页
This paper attempts to quantify the effect of backfilling on pillar strength in highwall mining using numerical modelling. Calibration against the new empirical strength formula for highwall mining was conducted to ob... This paper attempts to quantify the effect of backfilling on pillar strength in highwall mining using numerical modelling. Calibration against the new empirical strength formula for highwall mining was conducted to obtain the material parameters used in the numerical modelling. With the obtained coal strength parameters, three sets of backfill properties were investigated. The results reveal that the behavior of pillars varies with the type and amount of backfill as well as the pillar width to mining height ratio(w/h). In case of cohesive backfill, generally 75% backfill shows a significant increase in peak strength, and the increase in peak strength is more pronounced for the pillars having lower w/h ratios. In case of noncohesive backfill, the changes in both the peak and residual strengths with up to 92% backfill are negligible while the residual strength constantly increases after reaching the peak strength only when 100%backfill is placed. Based on the modelling results, different backfilling strategies should be considered on a case by case basis depending on the type of backfill available and desired pillar dimension. 展开更多
关键词 Highwall MINING BACKFILL COAL pillar Strength Numerical modelling
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Heavy rockbursts due to longwall mining near protective pillars:A case study 被引量:12
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作者 Petr Konicek Jan Schreiber 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2018年第5期799-805,共7页
Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The ... Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The case study describes a recorded heavy rockburst in the Czech part of the Upper Silesian Coal Basin, which occurred during longwall mining near the protective pillar. The artificial dividing of geological blocks and creation of mining protective pillars(shaft pillars, crosscut pillars etc.) is a dangerous task in light of rockbursts occurring mainly due to overstressing of remaining pillars. A simple model of this situation is presented. Natural and mining conditions are analysed and presented in detail as well as registered seismicity during longwall mining in the area. Recorded rockbursts in the area of interest are described and their causes discussed. Many rockbursts near protective pillars were recorded in this mining region. Methodical instructions for rockburst prevention in proximity of protective pillars as well as for gates driving were devised based on the evaluation of rockburst causes. The paper presents these principles for prevention. 展开更多
关键词 ROCKBURST ROCKBURST PREVENTION Hardcoal LONGWALL mining Induced SEISMICITY Protective pillar
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Limitations and potential design risks when applying empirically derived coal pillar strength equations to real-life mine stability problems 被引量:4
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作者 Russell Frith Guy Reed 《International Journal of Mining Science and Technology》 EI CSCD 2019年第1期17-25,共9页
The method of determining coal pillar strength equations from databases of stable and failed case histories is more than 50 years old and has been applied in different countries by different researchers in a range of ... The method of determining coal pillar strength equations from databases of stable and failed case histories is more than 50 years old and has been applied in different countries by different researchers in a range of mining situations. While common wisdom sensibly limits the use of the resultant pillar strength equations and methods to design scenarios that are consistent with the founding database, there are a number of examples where failures have occurred as a direct result of applying empirical design methods to coal pillar design problems that are inconsistent with the founding database. This paper explores the reasons why empirically derived coal pillar strength equations tend to be problem-specific and should be considered as providing no more than a pillar strength ‘‘index." These include the non-consideration of overburden horizontal stress within the mine stability problem, an inadequate definition of supercritical overburden behavior as it applies to standing coal pillars, and the non-consideration of overburden displacement and coal pillar strain limits. All of which combine to potentially complicate and confuse the back-analysis of coal pillar strength from failed cases. A modified coal pillar design representation and model are presented based on coal pillars acting to reinforce a horizontally stressed overburden, rather than suspend an otherwise unstable self-loaded overburden or section, the latter having been at the core of historical empirical studies into coal pillar strength and stability. 展开更多
关键词 Coal pillar DESIGN pillar strength OVERBURDEN MECHANICS LIMITATIONS of pillar DESIGN
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Coupling effects of coal pillars of thick coal seams in large-space stopes and hard stratum on mine pressure 被引量:11
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作者 Xia Binwei Jia Jinlong +2 位作者 Yu Bin Zhang Xuan Li Xiaolong 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第6期965-972,共8页
Concerning the issue of mine pressure behaviors occurred in fully mechanized caving mining of thick coal seams beneath hard stratum in Datong Mining Area, combined with thin and thick plate theory, the paper utilizes ... Concerning the issue of mine pressure behaviors occurred in fully mechanized caving mining of thick coal seams beneath hard stratum in Datong Mining Area, combined with thin and thick plate theory, the paper utilizes theoretical analysis, similar experiments, numerical simulations and field tests to study the influence of remaining coal pillars in Jurassic system goaf on hard stratum fractures, as well as mine pressure behaviors under their coupling effects. The paper concludes the solution formula of initial fault displacement in hard stratum caused by remaining coal pillars. Experiments prove that coupling effects can enhance mine pressure behaviors on working faces. When inter-layer inferior key strata fractures, mine pressure phenomenon such as significant roof weighting steps and increasing resistance in support.When inter-layer superior key strata fractures, the scope of overlying strata extends to Jurassic system goaf, dual-system stopes cut through, and remaining coal pillars lose stability. As a result, the bottom inferior key strata also lose stability. It causes huge impacts on working face, and the second mine pressure behaviors. These phenomena provide evidence for research on other similar mine strata pressure behaviors occurred in dual-system mines with remaining coal pillars. 展开更多
关键词 Dual system CAVING Coal pillar HARD rock Broken INSTABILITY Mining pressure REVEAL
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Stability and control of room mining coal pillars-taking room mining coal pillars of solid backfill recovery as an example 被引量:12
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作者 ZHANG Ji-xiong HUANG Peng +2 位作者 ZHANG Qiang LI Meng CHEN Zhi-wei 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第5期1121-1132,共12页
The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mini... The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mining method. During the damage progression of a single room coal pillar, the shape of the stress distribution in the pillar transformed from the initial stable saddle shape to the final arch-shaped distribution of critical instability. By combining the shapes of stress distribution in the coal pillars with the ultimate strength theory, the safe-stress value of coal pillar was obtained as 11.8 MPa. The mechanism of instability of coal pillar groups recovered by the caving mining method was explained by the domino effect. Since the room coal pillars mined and recovered by the traditional caving mining method were significantly influenced by the secondary mining during recovery, the coal pillars would go through a chain-type instability failure. Because of this limitation, the method of solid backfilling was proposed for mining and recovering room coal pillars, thus changing the transfer mechanism of stress caused by the secondary mining(recovery) of coal pillars. The mechanical model of the stope in the case of backfilling and recovering room coal pillars was built. The peak stress values inside coal pillars varied with the variance of backfilling ratio when the working face was advanced by 150 m. Furthermore, when the critical backfilling ratio was 80.6%, the instability failure of coal pillars would not occur during the solid backfill mining process. By taking Bandingliang Coal Mine as an example, the coal pillars' stability of stope under this backfilling ratio was studied, and a project scheme was designed. 展开更多
关键词 ROOM MINING stability of COAL pillarS COAL MINING of SOLID BACKFILL ultimate strength instability failure
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Numerical investigation into pillar failure induced by time-dependent skin degradation 被引量:10
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作者 Sainoki Atsushi Mitri Hani S. 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第4期591-597,共7页
This paper focuses on the instability mechanism of an isolated pillar, caused by time-dependent skin degradation and strength heterogeneity. The time-dependent skin degradation is simulated with a non-linear rheologic... This paper focuses on the instability mechanism of an isolated pillar, caused by time-dependent skin degradation and strength heterogeneity. The time-dependent skin degradation is simulated with a non-linear rheological model capable of simulating tertiary creep, whereby two different pillar failure cases are investigated. The first case is of an isolated pillar in a deep hard rock underground mine and subjected to high stresses. The results show that pillar degradation is limited to the regions near the surface or the skin until two months after ore extraction. Afterwards degradation starts to extend deeper into the pillar, eventually leaving a highly-stressed pillar core due to stress transfer from the failed skin.Rockburst potential indices show that the risk increases exponentially at the core as time goes by. It is then demonstrated that the progressive skin degradation cannot be simulated with conventional strain-softening model assuming brittle failure. The parametric study with respect to the degree of heterogeneity reveals that heterogeneity is key to the occurrence of progressive skin degradation. The second case investigated in this study is pillar failure taking place in a very long period. Such failure becomes significantly important when assessing the risk for ground subsidence caused by pillar collapse in an abandoned mine. The analysis results demonstrate that the employed non-linear rheological model can simulate gradual skin degradation taking place over several hundred years. The percentage of damage zone volume within the pillar is merely 1% after a lapse of one days and increases to 50% after one hundred years, indicating a high risk for pillar collapse in the long term. The vertical displacements within the pillar also indicate the risk of subsidence. The proposed method is suitable for evaluating the risk of ground surface subsidence above an abandoned mine. 展开更多
关键词 pillar stability Underground mine Skin degradation Rheological model Time-dependent failure
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Stress distribution and surrounding rock control of mining near to the overlying coal pillar in the working face 被引量:8
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作者 Rui Gao Bin Yu Xiangbin Meng 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2019年第6期881-887,共7页
The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the ... The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the numerical calculation with the account of OCP presence or absence.In addition,this study revealed the joint effect of side pressure relief area of the goaf and stress concentration in OCP on the final stress distribution.Furthermore,the rules of abutment stress distribution affected by three influencing factors,namely horizontal-vertical distances between OCP and working face and buried depth of OCP,are analyzed.The functional model linking the peak stress of surrounding rock with the above influencing factors is developed.The field application of the above results proved that the rib spalling and deformation of a 2.95 m-high and 5.66 m-wide roadway could be efficiently controlled by rationally adjusting working states of the support,and adopting the hydraulic prop coordinated with the p type metal beam and anchor cable to strengthen the surrounding rock of working face and roadway,respectively.The proposed measures are considered appropriate to satisfy the safe operation requirements. 展开更多
关键词 Overlying COAL pillar(OCP) Stress distribution Influencing factors SURROUNDING ROCK control
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Surrounding rock control of gob-side entry driving with narrow coal pillar and roadway side sealing technology in Yangliu Coal Mine 被引量:7
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作者 Zha Wenhua Shi Hao +1 位作者 Liu San Kang Changhao 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第5期819-823,共5页
Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation chara... Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition. 展开更多
关键词 Narrow coal pillar Gob-side ENTRY driving SURROUNDING rock control ROADWAY SIDE sealing technology
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Analysis of coal pillar stability(ACPS): A new generation of pillar design software 被引量:5
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作者 Christopher Mark Zach Agioutantis 《International Journal of Mining Science and Technology》 EI CSCD 2019年第1期87-91,共5页
Thirty years ago, the analysis of longwall pillar stability(ALPS) inaugurated a new era in coal pillar design.ALPS was the first empirical pillar design technique to consider the abutment loads that arise from full ex... Thirty years ago, the analysis of longwall pillar stability(ALPS) inaugurated a new era in coal pillar design.ALPS was the first empirical pillar design technique to consider the abutment loads that arise from full extraction, and the first to be calibrated using an extensive database of longwall mining case histories.ALPS was followed by the analysis of retreat mining stability(ARMPS) and the analysis of multiple seam stability(AMSS). These methods incorporated other innovations, including the coal mine roof rating(CMRR), the Mark-Bieniawski pillar strength formula, and the pressure arch loading model. They also built upon ever larger case history databases and employed more sophisticated statistical methods.Today, these empirical methods are used in nearly every underground coal mine in the US. However,the piecemeal manner in which these methods have evolved resulted in some weaknesses. For example,in certain situations, it may not be obvious which program is the best to use. Other times the results from the different programs are not entirely consistent with each other. The programs have also not been updated for several years, and some changes were necessary to keep pace with new developments in mining practice. The analysis of coal pillar stability(ACPS) now integrates all three of the older software packages into a single pillar design framework. ACPS also incorporates the latest research findings in the field of pillar design, including an expanded multiple seam case history data base and a new method to evaluate room and pillar panels containing multiple rows of pillars left in place during pillar recovery.ACPS also includes updated guidance and warnings for users and features upgraded help files and graphics. 展开更多
关键词 pillar design GROUND control STABILITY Empirical METHODS
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Structure instability forecasting and analysis of giant rock pillars in steeply dipping thick coal seams 被引量:9
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作者 Xing-ping Lai Huan Sun +3 位作者 Peng-fei Shan Ming Cai Jian-tao Cao Feng Cui 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2015年第12期1233-1244,共12页
Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams (SDTCS) are common in the Urumqi coalfield, and some dyna... Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams (SDTCS) are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining-induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sand- wiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam (TSFB). Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB's height (△H), which varied from 56.37 to 60.50 m. Next, FLAC^3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission (AE) energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS. 展开更多
关键词 coal mining structural instability rock pillars forecasting acoustic emission (AE) steeply dipping coal beds
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