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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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International Journal of Mining Science and Technology 2024年第5期34卷 713-729页

作者： Shili Qiu Shirui Zhang Quan Jiang Shaojun Li Hao Zhang Qiankuan Wang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University

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.

关键词： Pillar strength FDEM Voronoi tessellation Spalling bulking

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Pseudo-discontinuum model to simulate hard-rock mine pillars

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Underground Space 2023年第4期11卷 81-95页

作者： Erick Ro genes Alessandra dos Santos Gomes Marcio Muniz de Farias Leandro Lima Rasmussen Faculty of Technology University of BrasiliaDF 70910-900BrasiliaBrazil

In this study,the pseudo-discontinuum modeling technique,called continuum Voronoi block model(CVBM),was applied to repre-sent the behavior of hard-rock pillars from underground mines subjected to high field stresses.The CVBM’s ability to produce numerical results consistent with the observed behavior of pillars is demonstrated through the numerical analysis of a hypothetical case and a back analysis of the Creighton mine pillar.The results show that the model can capture convergence displacements and explicitly show the formation of macro-fractures parallel to excavation walls,intact rock slabs,and V-shaped notches.These components are characteristics of brittle failure induced by highly stressed ground conditions.The studies presented in this work confirm the CVBM as a convenient tool for the numerical modeling of intact rock pillars excavated in deep underground mines.

关键词： Brittle failure Spalling bulking Voronoi tessellation

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Management of process performance at low water temperatures in respect of filamentous organisms

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Journal of Environmental Sciences 2004年第1期16卷 113-116页

作者： WANGZeng-zhang NIUZhi-qing PELKONENMARKKU TaiyuanUniversityofTechnology China HelsinkiUniversityofTechnology Finland

The management of sludge-settling properties in Nordic conditions is of importance during the low temperature (spring) season because of the peak settler load. A survey was made in 10 Finnish waste water treatment plants(WWTP's) and the total extended filament length and DSVI in half of the plants exceeded the limits, which indicates sludge bulking(15 km/g SS and 150 ml/g respectively). The dominant organism was Microthrix parvicella, the abundance of which was 59.22% of total extended filament length on average. Chemicals were tested to control the filaments, and it was found that special attention has to be paid to maintaining the nitrification at low temperature. A dosage of(H_2O_2-based) oxidants controlled the growth of Microthrix parvicella effectively and rapidly, whereas with the use of aluminium hydroxidechloride a 2 to 5-week period was needed to decrease the filament length.

关键词： low temperature activated sludge bulking Microthrix parvicella chemical control nitrification

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Injectable treatments for female stress urinary incontinence

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World Journal of Clinical Urology 2014年第3期3卷 209-217页

作者： Omer Bayrak Stephen Mock Roger Roman Dmochowski Department of Urology School of Medicine University of Gaziantep University Boulevard27310 Gaziantep Turkey Department of Urology Vanderbilt University Medical CenterNashville TN 37232 United States

The use of injectable agents for the treatment of stress urinary incontinence(SUI)is an option for female patients who are unwilling to undergo surgery,or have concurrent conditions or diseases that render surgical treatment unsuitable.To be effective for SUI,an injectable agent must be nonimmunogenic,hypoallergenic,biocompatible,permanent,nonerosive,nonmigratory and painless.It must also heal with minimal fibrosis,possess a long-term bulking effect,and be easily stored and handled.Glutaraldehyde cross-linked bovine collagen(Contigen),silicone polymers(Macroplastique),Durasphere,calcium hydroxyapatite(Coaptite),polyacrylamide hydrogel(Aquamid,Bulkamid),Permacol,and stem cell therapy have been used as injectable agents.Patients must be informed that treatment with injectable agents is not as effective as surgical treatment,and that such agents might necessitate additional and repeated administrations in order to achieve the desired therapeutic effect.

关键词： Stress urinary incontinence Injectable treatment bulking agent Outcomes Adverse events

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Experiment Study on Movement and Damage of Overburden Under MiningFace Crossing Fault

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International Journal of Mining Science and Technology 2000年第1期21卷 58-61页

作者：谭志祥吴侃周鸣

Based on similar material model experiment, this paper studies the subsidence difference of fault hanging wall and lying wall when mining face crosses fault and the normal relative movement regularity of a fault zone. The change in bulking coefficients of fault zone, hanging wall and lying wall are given, the difference of mean bulking coefficients of two fault walls are discussed and the dynamic development pattern of fissure zone during mining face crossing fault is obtained.

关键词： mining face fault movement bulking coefficient fissure zone

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Effect of Deionization on Activated Sludge Characteristics: A Case Study of Activated Sludge Culture with Tap Water and Distilled Water

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Journal of Geoscience and Environment Protection 2019年第12期7卷 116-125页

作者： Pascaline Sanga Xiuqing Kong Kai Zhang College of Petrochemical Engineering Lanzhou University of Technology Lanzhou China

Activated sludge dewaterability and settleability properties are of prime importance in sludge treatment and disposal. Herein, we have experimentally examined the effect of deionization on activated sludge characteristics taking a case study of activated sludge inoculated in tap water and distilled water. The quality of the effluent, both distilled water and tap water were analyzed to determine the characteristics of activated sludge. Results indicated the increasing of the sludge volume index from 51.67 ml/g to 146.9 ml/g leading to the sludge bulking for sludge inoculated in distilled water. The Capillary Suction Time (CST) of sludge cultivated in distilled water varied from 23.1 to 38.4 s, which suggests poor dewaterability. These are due to the growth of some filamentous bacteria in distilled water system. These have further confirmed by light microscope images that showed a significant difference between the sludge systems cultivated in tap water and those grown in distilled water. The present work indeed advances our understanding of activated sludge treatment and would serve as a handy reference for researchers or scholars who want to deal with sewage water treatment.

关键词： Activated Sludge Sequential Batch Reactor Sludge Volume Index Sludge bulking Filamentous Bacteria

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