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Experimental study on expansion and cracking properties of static cracking agents in different assembly states

International Journal of Mining Science and Technology 2022年第6期32卷 1259-1272页

作者： Chong Li Sifeng He Wentao Hou Dan Ma school of mines China University of Mining and TechnologyXuzhou 221116JiangsuChina MOE Key Laboratory of Deep Coal Resource Mining China University of Mining and TechnologyXuzhou 221116JiangsuChina

Rolled static cracking agent(RSCA)can solve the intractable problem of traditional bulk static cracking agent(BSCA)in engineering applications.This paper innovatively studies the rational water-cement ratio of BSCA and the immersion soaking time of RSCA under the condition of controlling temperature.Through the expansion and cracking performance experiments,the development characteristics of expansion pressure,the cracking effect of the single-hole specimen and the performance of hole spraying prevention under the action of BSCA and RSCA were compared and analyzed.The results show that:(1)The volume growth rate of static cracking agent decreases with the increase of water-cement ratio,and the fluidity increases with the increase of water-cement ratio.The rational water-cement ratio for BSCA application is 0.3,and the rational immersion time of RSCA is 2-2.5 min;(2)Under the bore diameters of 30,35,40 and 45 mm,the expansion pressure of BSCA with a water-cement ratio of 0.3 is 38.2,52.3,61.5 and 68 MPa,and the expansion pressure of RSCA immersed in water for 2.5 min is 43.5,58.8,69.5 and 75.1 MPa,respectively.Among them,the development speed of expansion pressure of BSCA is higher than that of RSCA,and the arrival time of the peak expansion pressure of RSCA is 1.7 times that of BSCA;(3)The crack initiation speed of single-hole specimen under the action of RSCA is 10.3%lower than that under the action of BSCA,but the cracking speed of the former is 72.6%higher than that of the latter;(4)The hole spraying occurs in BSCA under the bore diameter of 50,55 and 60 mm,while the hole spraying occurs in RSCA under the bore diameter of 60 mm.In terms of bore diameter,the hole spraying prevention of the RSCA is better than that of BSCA.The research results enrich the static blasting technology and provide data support and theoretical reference for field application.

关键词： Static cracking agent water-cement ratio Static blasting Expansion pressure Hole spraying

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Numerical and analytical simulation of the structural behaviour of fully grouted cable bolts under impulsive loading

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International Journal of Mining Science and Technology 2018年第5期28卷 807-811页

作者： Faham Tahmasebinia Chengguo Zhang Ismet Canbulat Onur Vardar Serkan Saydam school of minerals and Energy Resources Engineering University of New South Wales

Designing reliable yielding support system to mitigate the effect of the kinetic energy in burst-prone conditions in mining and tunneling excavations is one of the challenges for geotechnical engineers. A combination of the support elements can be used to increase rock strength and minimise the displacement of unstable rock mass. It is important to understand how the support system works to ensure the stability of underground excavations. Cable bolts have been commonly used as an effective underground support system and an element of reinforcement to improve rock stability. Cable bolts are usually considered to be subjected to static loads under relatively low stress environments, however, in burst-prone conditions, they might be subjected to dynamic loads. Cable bolts as well as other support elements are used in burst-prone conditions to absorb the kinetic energy of the removed rock to avoid sudden and violent failures. This paper develops numerical and a novel analytical simulation technique for cable bolts to assess their structural behaviour under static and dynamic loading conditions. The numerical and analytical models are then validated against experimental observations reported in the literature, which demonstrates the reliability of the proposed models.

关键词： Cable bolts Yielding support Coal burst Shear dynamic loading

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Experimental investigation of evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill:Effect of curing temperature and curing time

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Frontiers of Structural and Civil Engineering 2023年第2期17卷 256-270页

作者： Kun FANG Liang CUI school of mines China University of Mining&TechnologyXuzhou 221116China Department of Civil Engineering Lakehead UniversityOntario P7B 5E1Canada

The curing temperature-dependent cement hydration causes the nonlinear evolution of fracture behavior and properties of fiber-reinforced cemented paste backfill(CPB)and thus influences the stability of mine backfill materials in deep mines.Therefore,the coupled effect of curing temperature(20,35,and 45℃)and cement hydration at different curing times(3,7,and 28 d)on the mode-I and mode-II fracture behavior and properties of fiber-reinforced CPB is investigated.A comprehensive experimental testing program consisting of semicircular bend tests,direct shear tests,measurement of volumetric water content and matric suction,TG/DTG tests,and SEM observation is carried out.The results show that the coupled thermochemical effect results in strongly nonlinear development of pre-and post-peak behavior of fiber-reinforced CPB.Moreover,the results discover a positive linear correlation between fracture toughness and shear strength parameters and also reveal the vital role played by matric suction in the formation of fracture toughness.Furthermore,predictive functions are developed to estimate the coupled thermochemical effect on the development of KIc and KIIc.Therefore,the findings and the developed mathematical tools have the potential to promote the successful application of fiber-reinforced CPB technology in deep underground mines.

关键词： fiber reinforcement cemented paste backfill fracture behavior underground mine cement hydration

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Mechanical performance of rock bolts under combined load conditions

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International Journal of Mining Science and Technology 2020年第2期30卷 167-177页

作者： P.C.Pinazzi A.J.S.(Sam)Spearing K.V.Jessu P.Singh R.Hawker Department of Mining and Metallurgical Engineering Western Australian School of MinesCurtin UniversityKalgoorlieWA 6430Australia Minova Global NowraNSW 2541Australia

Rock bolts are subjected to different loading conditions along their lengths such as axial,bending,and/or shear forces,which can cause failure at lower loads than those considered for design purposes.The common existing methodologies do not consider the actual loading of the rock bolts and assume it is only pure axial or pure shear.This study was conducted to investigate the un-grouted rock bolt performance under combined load conditions.Two loading regimes were evaluated:the effect of initial shear displacement on axial load capacity and displacement,and the effect of axial displacement on the shear load capacity.The first regime was also conducted for shear with a gap,when there is a spacing between the shear interfaces.The results of this study showed that the rock bolt can resist higher axial loads than shear under pure or combined load conditions.Under combined load conditions,the rock bolt capacity decreased significantly for both regimes.However,when applying the shear load with a gap,the rock bolt load capacity was not affected significantly.Also,the total bar deformation was improved for shear and axial.The findings of this study show the need to improve the rock bolt design considering the complex loading conditions in situ with/without a gap.

关键词： Rock bolt Combined load Gap test Failure mechanism Axial load Shear load

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Demand side management for solving environment constrained economic dispatch of a microgrid system using hybrid MGWOSCACSA algorithm

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CAAI Transactions on Intelligence Technology 2022年第2期7卷 256-267页

作者： Sourav Basak Bishwajit Dey Biplab Bhattacharyya Department of Electrical Engineering Indian Institute of Technology(Indian School of Mines)DhanbadIndia Department of Electrical and Electronics Engineering Gandhi Institute of Engineering and TechnologyGunupurOdishaIndia

Microgrids are a type of restricted power distribution systems in which electricity is generated,transmitted,and distributed within a small geographic region.They are used to ensure that renewable energy sources are used to their full potential.Microgrids provide further benefits,such as lowering transmission losses and the expenses associated with them.This research compares and contrasts the aims of economic dispatch,emission dispatch,fractional programing based combined economic emission dispatch,and environmental restricted economic dispatch(ECED).A low-voltage microgrid system is investigated for three different scenarios.As a study optimization tool,an innovative,resilient,and strong hybrid swarm-intelligence optimization algorithm is utilised,which is based on combining the properties of the traditional grey-wolf optimiser,sine-cosine algorithm,and crow search algorithm.The employment of a time-of-use energy mar-ket pricing approach instead of a fixed pricing plan resulted in a 15%decrease in gen-eration costs throughout the course of the research.When ECED was assessed with a 15%-20%demand side management based restructured load demand model for the microgrid system,the generation costs were reduced even further.

关键词： demand side management energy management MGWOSCACSA microgrid

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Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology

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Geoscience Frontiers 2016年第4期7卷 581-589页

作者： Christopher J.Spencer Christopher L.Kirkland Richard J.M.Taylor The Institute of Geoscience Research(TIGeR) Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Centre for Exploration Targeting-Curtin Node Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Australian Research Council Centre of Excellence for Core to Crust Fluid SystemsPerthWA 6102Australia

Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.

关键词： Zircon Geochronology U-Pb Geostatistics MSWD

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Provenance studies on the heavy mineral placers along the coastal deposits of Odisha,eastern India

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Journal of Palaeogeography 2022年第2期11卷 275-285页

作者： Shayantani Ghosal Sudha Agrahari Debashish Sengupta Department of Geology and Geophysics Indian Institute of Technology KharagpurWest BengalIndia Department of Applied Geology Indian Institute of Technology(Indian School of Mines)DhanbadJharkhandIndia

The coastal deposits along the eastern part of the Indian Peninsula are known for the high abundance of heavy minerals. The present study, as discussed here, has been undertaken along the southwestern coastal part of Odisha, India, adjoining the charnockite-migmatite zone of the Eastern Ghat Mobile Belt(EGMB). The composition of the placers along the study area is primarily controlled by the detritus from the proximal hinterland rock type(s). The weathering index has been established based on the grain morphology, major element concentration and radioelement ratios. Petrological characteristics and grain morphology of monazite, zircon, ilmenite and rutile have been presented respectively, and their implications are discussed. The provenance study of these coastal placers is based on the abundance of rare earth elements(REE) and radioactive elements in the placer sands and the rock types in the study area. The tectonic implications are based on the major element abundance of the beach sands.

关键词： Monazite placers High background radiation area(HBRA) Eastern Ghat Mobile Belt(EGMB) Weathering Zircon Rare earth elements(REE) East coast of India

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A new generic open pit mine planning process with risk assessment ability

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International Journal of Coal Science & Technology 2016年第4期3卷 407-417页

作者： Ngoc Luan Mai Oktay Erten Erkan Topal Westem Australian school of mines Curtin University of Technology Bentley WA 6102 Australia Nazarbayev University Astana Kazakhstan

Conventionally, mining industry relies on a deterministic view, where a unique mine plan is determined based on a single resource model. A major shortfall of this approach is the inability to assess the risk caused by the well-known geological uncertainty, i.e. the in situ grade and tonnage variability of the mineral deposit. Despite some recent attempts in developing stochastic mine planning models which have demonstrated promising results, the industry still remains sceptical about this innovative idea. With respect to unbiased linear estimation, kriging is the most popular and reliable deterministic interpolation technique for resource estimation and it appears to remain its popularity in the near future. This paper presents a new systematic framework to quantify the risk of kriging-based mining projects due to the geological uncertainties. Firstly, conditional simulation is implemented to generate a series of equally-probable orebody realisations and these realisations are then compared with the kriged resource model to analyse its geological uncertainty. Secondly, a production schedule over the life of mine is determined based on the kriged resource model. Finally, risk profiles of that production schedule, namely ore and waste tonnage production, blending grade and Net Present Value (NPV), are constructed using the orebody realisations. The proposed model was applied on a multi-element deposit and the result demonstrates that that the kriging-based mine plan is unlikely to meet the production targets. Especially, the kriging-based mine plan overestimated the expected NPV at a magnitude of 6.70% to 7.34% (135 M$ to 151 M$). A new multivariate conditional simulation framework was also introduced in this paper to cope with the multivariate nature of the deposit. Although an iron ore deposit is used to prove the concepts, the method can easily be adapted to other kinds of mineral deposits, including surface coal mine.

关键词：风险评估规划模型露天矿 Kriging 资源模型克里格法生产计划通用

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Preparation of high-purity tantalum ethoxide by vacuum distillation

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中国有色金属学会会刊：英文版 2008年第1期18卷 196-201页

作者：杨声海陈永明杨海平刘银元唐谟堂邱冠周 school of Metallurgical Science and Engineering Central South University school of minerals Processing and Bioengineering

Effects of reflux ratio,water addition and content of water in ethanol on the purity and yield of tantalum ethoxide during vacuum distillation were investigated under the operational conditions of pressure of 1 kPa,oil bath temperature of 210-230 ℃,and outlet temperature of 190 ℃.The condensate sample was characterized by FTIR,1H-NMR spectroscopy and Raman spectra,respectively.The contents of tantalum,carbon and hydrogen in the sample were also determined with elemental analysis instrument.The obtained results consistently demonstrate that the condensate is tantalum ethoxide.The content of impurity,such as Al,As,Ca,Co,Cr,Cu,Fe,K,Mg,Mn,Mo,Na,Ni,Pb,Sn,Ti,V and Zn,in tantalum ethoxide is less than 0.000 05%,while Nb content is less than 0.000 5%.The content of impurities in tantalum ethoxide sample excels that of Epichem Group's requirement for Ta(OC2H5)5 of 99.999%.

关键词：高纯度乙醇钽真空蒸馏杂质化学制剂

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Computing the damage and fracture energy in a coal mass based on joint density

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International Journal of Mining Science and Technology 2018年第5期28卷 813-817页

作者： Faham Tahmasebinia Chengguo Zhang Ismet Canbulat Onur Vardar Serkan Saydam school of minerals and Energy Resources Engineering University of New South Wales

Coal joints and cleats are geological discontinuities that are the most important factors that affect the mechanical responses of a coal mass under stress. The joint and coal mass interaction and the mode of failure dominate the mechanical behaviour of jointed coal masses, and therefore the stability of coal excavations. The shear or mixed shear/tensile failure changes to tensile failure by increasing the confining pressure, discontinuity length and angle. This paper extends a thermodynamic approach to constitutive modelling of the coal mass by developing local and non-local damage models based on the joint and cleat density and the dip angle. A consistent and rigorous statistical framework is constructed, which incorporates both local and non-local features into the constitutive modelling. This is an important consideration in developing damage constitutive models based on the trajectory of the failure surfaces in a coal mass.An equation is derived to calculate the fracture energy which is a function of the joint density either in a single direction or crossed conditions.

关键词： Joint density Dissipated energy Coal mass Damage model

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