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Experimental investigation and flow analysis of clear-water scour around pier and Abutment in proximity

Water Science and Engineering 2023年第1期16卷 94-105页

作者： Mohammad Saeed Fakhimjoo Abdollah Ardeshir Kourosh Behzadian Hojat Karami Department of Civil and Environmental Engineering Amirkabir University of TechnologyTehran 15875-4413Iran School of Computing and Engineering University of West LondonLondon W55RFUK Department of Civil Engineering Semnan UniversitySemnan 35131-19111Iran

Local scour around bridge piers and Abutments is one of the most significant causes of bridge failure.Despite a plethora of studies on scour around individual bridge piers or Abutments,few studies have focused on the joint impact of a pier and an Abutment in proximity to one another on scour.This study conducted laboratory experiments and flow analyses to examine the interaction of piers and Abutments and their effect on clear-water scour.The experiments were conducted in a rectangular laboratory flume.They included 18 main tests(with a combination of different types of piers and Abutments)and five control tests(with individual piers or Abutments).Three pier types(a rectangular pier with a rounded edge,a group of three cylindrical piers,and a single cylindrical pier)and two Abutment types(a wingewall Abutment and a semicircular Abutment)were used.An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline,velocity magnitude,vertical velocity,and bed shear stress.The results showed that the velocity near the pier and Abutment increased by up to 80%.The maximum scour depth around the Abutment increased by up to 19%.In contrast,the maximum scour depth around the pier increased significantly by up to l71%.The presence of the pier in the vicinity of the Abutment led to an increase in the scour hole volume by up to 87%relative to the case with a solitary Abutment.Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the Abutment.

关键词： Abutment ADV Bridge scour Laboratory experiment Maximum scour depth Pier

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Abutment pressure distribution for longwall face mining through abandoned roadways

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International Journal of Mining Science and Technology 2019年第1期29卷 59-64页

作者： Yang Li Mingxing Lei Haosen Wang Cheng Li Weiwei Li Yang Tao Jingyi Wang College of Resources and Safety Engineering China University of Mining and Technology Beijing China National Machinery Imp&Exp.Corp

Abutment pressure distribution is different when a longwall panel is passing through the abandoned gate roads in a damaged coal seam. According to the geological condition of panel E13103 in Cuijiazhai Coal Mine in China, theoretical analysis and finite element numerical simulation were used to determine the front pressure distribution characteristics when the longwall face is 70, 50, 30, 20, 10, and 5 m from the abandoned roadways. The research results show that the influence range of Abutment pressure is 40 to 45 m outby the face, and the peak value of front Abutment pressure is related to the distance between the face and abandoned roadways. When the distance between the longwall face and abandoned roadways is reduced from 50 to 10 m, the front Abutment pressure peak value kept increasing. When the distance is 10 m, it has reached the maximum. The peak value is located in 5 to 6 m outby the faceline. When the distance between the longwall face and abandoned roadways is reduced from 10 to 5 m, the front Abutment pressure sharply decreases, the intact coal yields and is even in plastic state. The peak value transfers to the other side of the abandoned roadways. The research results provide a theoretical basis for determining the advance support distance of two roadways in the panel and the reinforcement for face stability when the longwall face is passing through the abandoned roadways.

关键词： Abandoned roadways Abutment pressure Theoretical calculation Numerical simulation

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Analysis of ARMPS2010 database with LaModel and an updated Abutment angle equation

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International Journal of Mining Science and Technology 2020年第1期30卷 111-118页

作者： Deniz Tuncay Ihsan Berk Tulu Ted Klemetti Department of Mining Engineering West Virginia UniversityMorgantownWV 26505USA National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

The Analysis of Retreat Mining Pillar Stability(ARMPS) program was developed by the National Institute for Occupational Safety and Health(NIOSH) to help the United States coal mining industry to design safe retreat room-and-pillar panels. ARMPS calculates the magnitude of the in-situ and mining-induced loads by using geometrical computations and empirical rules. In particular, the program uses the "Abutment angle" concept in calculating the magnitude of the Abutment load on pillars adjacent to a gob. In this paper, stress measurements from United States and Australian mines with different overburden geologies with varying hard rock percentages were back analyzed. The results of the analyses indicated that for depths less than 200 m, the ARMPS empirical derivation of a 21° Abutment angle was supported by the case histories;however, at depths greater than 200 m, the Abutment angle was found to be significantly less than 21°. In this paper, a new equation employing the panel width to overburden depth ratio is constructed for the calculation of accurate Abutment angles for deeper mining cases. The new Abutment angle equation was tested using both ARMPS2010 and La Model for the entire case history database of ARMPS2010. The new Abutment angle equation to estimate the magnitude of the mining-induced loads used together with the La Model program was found to give good classification accuracies compared to ARMPS2010 for deep cover cases.

关键词： Abutment angle ARMPS2010 LaModel ARMPS-LAM Coal mining Pillar stability

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Relevance between Abutment pressure and fractal dimension of crack network induced by mining

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International Journal of Mining Science and Technology 2013年第6期23卷 925-930页

作者： Gao Mingzhong Jin Wencheng Dai Zhixu Xie Jing State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University College of Hydraulic and Hydropower Engineering Sichuan University Energy&Chemical Industry Research Institute Shenma Group of Pingdingshan Coal Group College of Architecture and Environment Sichuan University

Based on the geological conditions of coal mining face No.15-14120 at No.8 mine of Pingdingshan coal mining group,the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument.And according to the geology of this working face,a discrete element model was calculated by UDEC.Combining in situ experimental data with numerical results,the relationship between the fractal dimension of boreholes'wall and the distribution of advanced Abutment pressure was studied under the condition of mining advance.The results show that the variation tendency of fractal dimension and the Abutment pressure has the same characteristic value.The distance between working face and the peak value of the Abutment pressure has a slight increasing trend with the advancing of mining-face.When the working face is set as the original point,the trend of fractal dimension from the far place to the origin can be divided into three phases:constant,steady increasing and constant.And the turning points of these phases are the max-influencing distance(50 m)and peak value(15 m)of Abutment pressure.

关键词： Advanced Abutment pressure Fractal dimension Evolution Discrete element

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Formation and evolution of gas flow channels in the Abutment pressure area

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International Journal of Mining Science and Technology 2012年第6期22卷 801-807页

作者： Zhang Yong Zhang Xibin Xu Lifeng Zhang Jiangli Zhou Genli Faculty of Resources and Safety Engineering China University of Mining and Technology Huaneng Coal Industry Co. Ltd.

The permeability of coal ahead of the working face obviously changes dues to changes in Abutment pressure.The formation and evolution of gas flow channels within the Abutment pressure area was studied by analyzing the fracture extension mechanism and fracture development in different zones of the Abutment pressure area.Fracture and damage mechanics theory is used to understand the observations.The following two techniques were used to understand the evolution of gas flow channels:field observation of the characteristic fractures at different positions relative to the working face and fluorescence micrographs of prepared coal samples.Bending tensile fractures develop along an approximately vertical direction that forms a microscopic network of channels in areas of stress concentration.The Abutment pressure affects the local stress and,hence,the local gas conduction.The fractures induced by large deformation and plastic flow form macroscopically networked channels in the reduced stress area.Closer to the working face the gas flow channels evolve from microscopic to macroscopic and from isolated to network.Gas permeability continuously increases during this time.This is corroborated by field observations of the displacement of top coal and the gas flow from gas extraction drillings.

关键词： Abutment pressure Gas flow channels Fracture extension mechanism Fracture development characteristics Evolution process

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Influence of Abutment Material on the Stress of Implant-supported All-ceramic Single Crown

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Journal of Wuhan University of Technology(Materials Science) 2012年第1期27卷 96-99页

作者：高少怀 DUAN Haiying 李智勇 Department of Prosthodontics School and Hospital of StomatologyWuhan UniversityWuhan 430079China Department of Stomatology Wuhan Central Hospital of China Construction Third Engineering Bureau Co.Ltd.Wuhan 430079China

In order to investigate the influence of Abutment material on the stress of implant-supported all-ceramic single crown, a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M 2.85 software. Alumina, zirconia, and titanium were used as Abutment materials respectively. Vertical 600 N and horizontal 225 N load was applied on the occlusal surface. The results show that the stress distribution of implant-supported single crown was similar for different Abutment materials. Maximum stresses within the crown were higher when titanium Abutment was used. Maximum stress of titanium Abutment was lower than that of ceramic Abutment. Within the screw and fixture, maximum stresses had no difference under vertical loading but higher as titanium Abutment was used under horizontal loading. There was no difference of maximum stress within the bone when different Abutment materials were used. The present findings indicate that the Abutment material had no influence on the stress distribution of implant-supported all- ceramic single crown but maximum stress when the titanium Abutment was lower than that of ceramic Abutment.

关键词： finite element analysis dental implant stress all-ceramic Abutment

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Effects of clinical dental implant Abutment materials and their surface characteristics on initial bacterial adhesion

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Rare Metals 2019年第6期38卷 512-519页

作者： Yu-Shan Huang Her-Hsiung Huang Department of Dentistry National Yang-Ming UniversityTaipei 112TaiwanChina Division of Dentistry National Yang-Ming University HospitalI-Lan 260TaiwanChina Institute of Oral Biology National Yang-Ming UniversityTaipei 112TaiwanChina Department of Bioinformatics and Medical Engineering Asia UniversityTaichung 413TaiwanChina Department of Medical Research China Medical University HospitalTaichung 404TaiwanChina Graduate Institute of Basic Medical Science China Medical UniversityTaichung 404TaiwanChina Department of Stomatology Taipei Veterans General HospitalTaipei 112TaiwanChina Department of Education and Research Taipei City HospitalTaipei 110TaiwanChina

Initial bacterial adhesion on dental implant Abutment is related to its surface chemical composition and physical characteristics.Selection of appropriate Abutment materials resistant to bacterial adhesion is important for dental implant maintenance.The aim of present study was to evaluate the effect of different properties of Abutment materials on initial bacterial adhesion in vitro.Polished zirconia(PZ group), polished titanium(PT group) and ground titanium(GT group) samples were prepared to simulate clinical dental implant Abutments.Chemical compositions, morphology, roughness, hydrophilicity and surface free energy of materials were analyzed.Oral commensal bacterium Streptococcus mitis was used to evaluate initial bacterial adhesion via turbidity test and colony-forming unit counting.The results showed that GT group presented the highest roughness, hydrophilicity and surface free energy.After 6-h incubation, GT group showed the significantly highest adhered bacteria counts;while non-significant difference existed between PT and PZ groups.Within the clinically applicable range used in present study, the surface physical characteristics, instead of surface chemical composition, of dental Abutment material have the pronounced influence on initial 6-h bacterial adhesion.

关键词： Dental implant Abutment Bacterial adhesion Zirconia Titanium Surface characteristics

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A case study of the stability of a non-typical bleeder entry system at a U.S.longwall mine

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International Journal of Mining Science and Technology 2020年第1期30卷 25-31页

作者： T.M.Klemetti M.A.Van Dyke I.B.Tulu D.Tuncay NIOSH Pittsburgh Mining Research Division Pittsburgh 15236USA Department of Mining Engineering West Virginia UniversityMorgantown 26505USA

Longwall Abutment loads are influenced by several factors,including depth of cover,pillar sizes,panel dimensions,geological setting,mining height,proximity to gob,intersection type,and size of the gob.How does proximity to the gob affect pillar loading and entry condition?Does the gob influence depend on whether the Abutment load is a forward,side,or rear loading?Do non-typical bleeder entry systems follow the traditional front and side Abutment loading and extent concepts?If not,will an improved understanding of the combined Abutment extent warrant a change in pillar design or standing support in bleeder entries?This paper details observations made in the non-typical bleeder entries of a moderate depth longwall panel—specifically,data collected from borehole pressure cells and roof extensometers,observations of the conditions of the entries,and numerical modeling of the bleeder entries during longwall extraction.The primary focus was on the extent and magnitude of the Abutment loading experienced due to the extraction of the longwall panels.Due to the layout of the longwall panels and bleeder entries,the borehole pressure cells(BPCs)and roof extensometers did not show much change due to the advancing of the first longwall.However,they did show a noticeable increase due to the second longwall advancement,with a maximum of about 4 MPa of pressure increase and 5mmof roof deformation.The observations of the conditions showed little to no change from before the first longwall panel extraction began to when the second longwall panel had been advanced more than 915 m.Localized pillar spalling was observed on the corners of the pillars closest to the longwall gob as well as an increase in water in the entries.In addition to the observations and instrumentation,numerical modeling was performed to validate modeling procedures against the monitoring results and evaluate the bleeder design.ITASCA Consulting Group’s FLAC3D numerical modeling software was used to evaluate the bleeder entries.The results of the models indicate

关键词： Abutment loading Longwall Instrumentation Bore hole pressure cells Pillar loading Yield pillar Bleeder pillar

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Numerical simulation of roof cavings in several Kuzbass mines using finite-difference continuum damage mechanics approach

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International Journal of Mining Science and Technology 2020年第2期30卷 157-166页

作者： Mikhail Eremin Gabriel Esterhuizen Igor Smolin Institute of Strength Physics and Materials Science Siberian BranchRussian Academy of SciencesTomsk 634055Russian Federation National Institute for Occupational Safety and Health PittsburghPA 15236USA National Research Tomsk State University Tomsk 634050Russian Federation

An essential stage of mine design is an estimation of the steps of the first and periodic roof caving in longwall mines.Generally,this is carried out using the field experience and can be much enhanced by numerical simulation.In this work,the finite-difference method was applied coupled with the continuum damage mechanics(CDM)approach to simulate the stress-strain evolution of the rock mass with the underground opening during coal extraction.The steps and stages of roof caving were estimated relying on the numerical simulation data,and they were compared with the field data from several operating mines in the south of the Kuznetsk Basin,Russia.The dependence of the first roof caving step in simulation linearly correlates with field data.The results correspond to the actual roofs of longwall panels of the flat-dipping coal seams and the average rate of face advancement is approximately 5 m/day.

关键词： Longwall mining Rock mass Underground openings Roof caving Abutment pressure Numerical simulation

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Deep cover bleeder entry performance and support loading: A case study

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International Journal of Mining Science and Technology 2018年第1期28卷 85-93页

作者： Ted M.Klemetti Mark Alexander Van Dyke Ihsan Berk Tulu Ground Control Branch NIOSHPittsburgh Mining Research Division Mining Engineering Department West Virginia University

Several questions have emerged in relation to deep cover bleeder entry performance and support loading:how well do current modeling procedures calculate the rear Abutment extent and loading? Does an improved understanding of the rear Abutment extent warrant a change in standing support in bleeder entries? To help answer these questions and to determine the current utilization of standing support in bleeder entries, four bleeder entries at varying distances from the startup room were instrumented,observed, and numerically modeled.This paper details observations made by NIOSH researchers in the bleeder entries of a deep cover longwall panel—specifically data collected from instrumented pumpable cribs, observations of the conditions of the entries, and numerical modeling of the bleeder entries during longwall extraction.The primary focus was on the extent and magnitude of the Abutment loading experienced by the standing support.As expected, the instrumentation of the standing supports showed very little loading relative to the capacity of the standing supports—less than 23 Mg load and 2.54 cm convergence.The Flac3D program was used to evaluate these four bleeder entries using previously defined modeling and input parameter estimation procedures.The results indicated only a minor increase in load during the extraction of the longwall panel.The model showed a much greater increase in stress due to the development of the gateroad and bleeder entries, with about 80% of the increase associated with development and 20% with longwall extraction.The Flac3D model showed very good correlation between expected gateroad loading during panel extraction and that expected based on previous studies.The results of this study showed that the rear Abutment stress experienced by this bleeder entry design was minimal.The farther away from the startup room, the lower the applied load and smaller the convergence in the entry if all else is held constant.Finally, the numerical modeling method used in this study was capable of replicating t

关键词： Bleeder entry Standing supports Abutment loading Longwall mining Full extraction

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