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Effects of pressure relief holes on coal burst:Insights from true-triaxial unloading tests

Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3378-3394页

作者： Fuqiang Ren murat karakus Giang Nguyen Thomas Bruning School of Civil Engineering University of Science and Technology LiaoningAnshan114051China Mining and Petroleum Engineering The University of AdelaideAdelaideSouth Australia5005Australia State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining and TechnologyBeijing100083China School of Architecture and Civil Engineering The University of AdelaideSouth Australia5005Australia

Drilling pressure relief is one of the methods to reduce the risk of coal bursts in deep ***,the effect of the drill hole orientations has not been studied well enough to understand their impact on the burst failure *** this study,we investigated two designs of drill hole *** first design includes drill holes located on the upper free face of the rectangular samples and labelled as upper hole(UH)and centre hole(CH)e the long axes of the drill holes are aligned with minor principal stress,s3,*** second design includes drill holes at the top(TH)and the side(SH)of the rectangular samples in which the long axes of the drill holes are aligned with the maximum,s1,and intermediate principal stress,s2,directions,*** coal samples with the proposed drill hole orientations were subjected to the true-triaxial unloading coal burst *** results show that the drill holes reduce the risk of coal ***,we found that the intensity of coal burst was significantly reduced with the SH-type,followed by the *** also observed that the coal burst intensity is reduced better for the CH,UH,TH,and SH-type drilling ***,it was found that the orientations of drill holes have little influence on the failure mode(splitting).The acoustic emission(AE)activities for coal with drill holes noticeably decreased,especially for the UH and CH *** drill holes reduced the upper limit of the AE entropy(chaos of microcracks generation).However,regarding reducing the coal burst risk,the TH and SH are less effective than UH and CH.

关键词： Coal burst Triaxial unloading Drilling orientation Ejection characteristic Acoustic emission(AE)

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Effects of water content, water type and temperature on the rheological behaviour of slag-cement and fly ash-cement paste backfill

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International Journal of Mining Science and Technology 2020年第3期30卷 271-278页

作者： Yue Zhao Abbas Taheri murat karakus Zhongwei Chen An Deng School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaide 5005Australia School of Mechanical and Mining Engineering The University of QueenslandBrisbane 4072Australia

The pumping ability and placement performance of fresh cemented paste backfill(CPB) in underground mined cavities depend on its rheological properties. Hence, it is crucial to understand the rheology of fresh CPB slurry, which is related to CPB mixture design and the temperature underground. This paper presented an experimental study investigating the effects of binder type, content, water chemical properties and content, and temperature, on the rheological properties of CPB material prepared using the tailings of a copper mine in South Australia. Portland cement(PC), a newly released commercially manufactured cement called Minecem(MC) and fly ash(FA) were used as the binders added to the mine tailing materials. Various amounts of two different water types were added to the mixtures in the preparation of backfill material slurry. Six different temperatures ranging from 5 to 60 °C were to investigate the effect of temperature on CPB rheology. Overall, the increasing water content and decreasing temperature lead to lower yield stress. Based on the results obtained from the rheological properties of CPB slurry, it was found that at room temperature(25 °C), with regards to the unconfined compressive strength(UCS) performance, the replacement of 4% PC mixed CPB(28 days UCS 425 k Pa) to 3% MC mixed CPB(28 days UCS 519 k Pa), reduced the slurry yield stress from 210.7 to 178.5 Pa. The results also showed that the chemical composition of water affects the yield stress of CPB slurry and that MC mitigates the negative effect of mine-processed water(MW) and thus lead to improve the rheological properties of the slurry. However, the results suggested that the rheological properties of a mixture using MC is very sensitive to the water volume and temperature change. Therefore, using MC in backfill requires better quality control in slump mixing.

关键词： Cemented paste backfill Minecem Rheology Yield stress Fly ash Portland cement

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Effect of loading rate and time delay on the tangent modulus method(TMM)in coal and coal measured rocks

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International Journal of Coal Science & Technology 2022年第6期9卷 51-63页

作者： Zulfiqar Ali murat karakus Giang D.Nguyen Khalid Amrouch School of Civil Environmental and Mining EngineeringUniversity of AdelaideAdelaideSA 5000Australia Australian School of Petroleum and Energy University of AdelaideAdelaideSA 5000Australia Geology&Sustainable Mining Mohammed VI Polytechnic University43150 BenguerirMorocco

Non-destructive techniques of in-situ stress measurement from oriented cored rocks have great potential to be developed as a cost cost-effective and reliable alternative to the conventional overcoring and hydraulic fracturing *** tangent modulus method(TMM)is one such technique that can be applied to oriented cored rocks to measure in-situ *** the deformation rate analysis(DRA),the rock specimen is subjected to two cycles of uniaxial compression and the stress-tangent modulus curve for the two cycles is obtained from the stress-strain curve.A bending point in the tangent modulus curve of the first cycle is observed,separating it from the tangent modulus curve of the second *** point of separation between the two curves is assumed to be the previously applied maximum stress.A number of experiments were conducted on coal and coal measured rocks(sandstone and limestone)to understand the effect of loading conditions and the time *** specimens were preloaded,and cyclic compressions were applied under three different modes of loading,four different strain rates,and time delays of up to one *** bending point in the stress-tangent modulus curves occurred approximately at the applied pre-stress levels under all three loading modes,and no effect of loading rate was observed on the bending points in ***,a clear effect of time delay was observed on the TMM,contradicting the DRA *** could be due to the sensitivity of TMM and the range of its applicability,all of which need further investigation for the in-situ stress measurement.

关键词： Tangent modulus method TMM Deformation rate analysis DRA Time delay Strain rate

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Influence of deviatoric stress on rockburst occurrence:An experimental study

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International Journal of Mining Science and Technology 2018年第5期28卷 763-766页

作者： Thomas Bruning murat karakus Selahattin Akdag Giang D.Nguyen David Goodchild School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaide 5005Australia OZ Minerals 2 Hamra DriveAdelaide AirportSA5950Australia

As mining delves deeper into the crust, it is necessary to investigate the complex rock responses associated with higher stress gradients. Therefore, it is essential to better understand the mechanisms associated with the rockburst phenomenon. However, due to the large-scale and difficult monitoring of real mining excavations, laboratory scale tests must be utilised to determine the conditions conducive to burst. To this end, this research focuses on the implementation of a new rockburst testing apparatus to replicate the stress conditions of a rock mass excavation at the time of bursting. This apparatus allows the determination of rockburst stresses and a relationship between deviatoric stress and in-situ pressure/depth. Using this relationship it is then possible to estimate the standardised stress levels for a certain rock type which might lead to rockburst occurrence. Furthermore, it is demonstrated that with increasing in-situ pressure, the likelihood(measured as a lower differential stress) and the extent(indicated by the increasing range of deviatoric stress) of rockburst increases. These findings provide valuable information about the conditions necessary for bursting in deep mining.

关键词： Rockburst test Hollow cylinder Hard rock In-situ stress

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The collision experiment between rolling stones of different shapes and protective cushion in open-pit mines

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Journal of Mountain Science 2021年第5期18卷 1391-1403页

作者： ZHU Chun HE Man-chao karakus murat ZHANG Xiao-hu GUO Zhen School of Earth Sciences and Engineering Hohai UniversityNanjing 210098China Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil&Gas Reservoirs in West China Ministry of EducationXi'an Shiyou UniversityXi'an 710021China State Key Laboratory for Geomechanics&Deep Underground Engineering Beijing 100083China School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaide SA 5005Australia College of Civil Engineering Tongji UniversityShanghai 200092China

Though gravel cushions are used worldwide in open-pit mines and railway slopes to control the impact of rolling stones,no universal technical standards have been put in place to guide engineers in their correct design,and few laboratory test results are available with which to characterize collisions between rolling stones and a gravel *** carried out a large number of experiments in which rolling stones made of the same material but differently shaped were dropped from various heights onto cushions with various particle sizes and *** investigated the characteristics of the resulting collisions,and the relationships between coefficients of restitution(CORs)of blocks with different shape and release height H,cushion thickness h and particle diameter d are obtained through linear fitting *** testing reveals the relative influence of block shape,release height,and the particle size and thickness of the cushion on the collision characteristics,which can assist engineers in designing a gravel cushion suitable to the distribution and weathering characteristics of rolling stones in a specific area.

关键词： Coefficient of restitution(COR) Collision characteristics Gravel cushion Rolling stone shape

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Evaluation of the propensity of strain burst in brittle granite based on post-peak energy analysis

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Underground Space 2021年第1期6卷 1-11页

作者： Selahattin Akdag murat karakus Giang D.Nguyen Abbas Taheri Thomas Bruning School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaideSAAustralia

The increasing demand for resources and depletion of near ground mineral resources caused deeper mining operations under highstress rock mass *** a result of this,strain burst,which is the sudden release of stored strain energy in the surrounding rock mass,has become more prevalent and created a considerable threat to workers and construction *** is,therefore,imperative to understand how strain burst mechanism and stored excess strain energy are affected due to the high confinement in deep underground *** this purpose,post-peak energy distributions for brittle rocks were investigated using a newly developed energy calculation method associated with acoustic emission(AE).A series of quasi-static uniaxial and triaxial compression tests controlled by the circumferential expansion were ***-back behaviour known as Class-II behaviour associated with energy evolution and the material response under self-sustaining failure were analysed on granites under a wide range of confining pressures(0–60 MPa).The experimental results underline that the energy evolution characteristics are strongly linked to *** elastic strain energy(dUE),energy consumed by dominating cohesion weakening(dUCW)and energy dissipated during mobilisation of frictional failure(dUFM)showed a rising trend as the confining pressure was *** intrinsic ejection velocity was proposed to express the propensity of strain burst that was purely determined by the excess strain energy released from Class II rock.

关键词： Strain burst Energy balance Class II failure mode Self-sustaining failure Triaxial compression test Circumferential strain control

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Thermal damage constitutive model for rock considering damage threshold and residual strength

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Journal of Central South University 2018年第10期25卷 2523-2536页

作者： XU Xiao-li karakus murat GAO Feng ZHANG Zhi-zhen School of Architecture and Civil Engineering Nantong University State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology School of Civil Environmental and Mining Engineering the University of Adelaide

With the gradual depletion of mineral resources in the shallow part of the earth,resource exploitation continues to move deeper into the earth,it becomes a hot topic to simulate the whole process of rock strain softening,deformation and failure in deep environment,especially under high temperature and high *** the basis of Lemaitre’s strain-equivalent principle,combined with statistics and damage theory,a statistical constitutive model of rock thermal damage under triaxial compression condition is *** the same time,taking into account the existing damage model is difficult to reflect residual strength after rock failure,the residual strength is considered in this paper by introducing correction factor of damage variable,the model rationality is also verified by *** of results indicates that the damage evolution curve reflects the whole process of rock micro-cracks enclosure,initiation,expansion,penetration,and the formation of macro-cracks under coupled effect of temperature and confining *** thermal damage shows logistic growth function with the increase of *** the same strain condition,rock total damage decreases with the rise of confining *** studying the electron microscope images(SEM)of rock fracture,it is inferred that 35.40 MPa is the critical confining pressure of brittle to plastic transition for this *** model parameter F reflects the average strength of rock,and M reflects the morphological characteristics of rock stress–strain *** physical meanings of model parameters are clear and the model is suitable for complex stress states,which provides valuable references for the study of rock deformation and stability in deep engineering.

关键词： rock damage model temperature effect confining pressure damage threshold residual strength

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Dynamic Responses of Block Type Quay Walls Under Cyclic Loading

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China Ocean Engineering 2021年第2期35卷 281-290页

作者： Hulya karakus CIHAN Kubilay CIHAN Yuksel Project 06610 CankayaAnkaraTurkey Civil Engineering Department Hydraulics DivisionKırıkkale UniversityKırıkkaleTurkey

The purpose of this research is to study the dynamic responses of gravity quay walls with block type consisting of“three blocks”*** this purpose,1g shaking table tests were conducted under different cyclic loadings for two different saturated granular backfill materials(Soil 1 and Soil 2).In this study,D_(n50) of Soil 1 and Soil 2 are selected as 2.2 cm and 1.0 cm,*** the experiments,accelerations,soil pressures and displacements were measured for each *** results pointed out that Soil 2 caused more damage on *** measurements for displacement and tilting of each block were discussed in view of“acceptable level of damage in performance-based design”given in PIANC(2001).The result of the study showed that the definitions of damaged levels given in PIANC(2001)were reliable for using in performance-based methods for seismic design of block type quay walls.

关键词： block type quay walls 1g shaking table tests damage level dynamic response

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Evaluation of botanicals as potential COVID-19 symptoms terminator

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World Journal of Gastroenterology 2021年第39期27卷 6551-6571页

作者： Ufuk Koca Caliskan Methiye Mancak karakus Department of Pharmacognosy and Pharmaceutical Botany Gazi UniversityAnkara 06500Turkey

Information about the coronavirus disease 2019(COVID-19)pandemic is still evolving since its appearance in December 2019 and has affected the whole ***,a search for an effective and safe treatment for COVID-19 *** mixtures contain secondary metabolites(such as flavonoids,phenolics,alkaloids,essential oils etc.)with many therapeutic *** this study,the use of herbal treatments against COVID-19 was *** synthetic drugs focus mainly on respiratory symptoms,however herbal therapy with plant extracts may be useful to relieve overall symptoms of COVID-19 due to the variety of bioactive *** COVID-19 is a virus that affects the respiratory tract,the antiviral effects of botanicals/plants against respiratory viruses have been examined through clinical *** about COVID-19 patients revealed that the virus not only affects the respiratory system but different organs including the gastrointestinal(GI)*** GI symptoms seriously affect quality of life,herbal options that might eliminate these problems were also ***,computer modeling studies of plants and their active compounds on COVID-19 were *** summary,herbal therapies were identified as potential options for both antiviral effects and control of COVID-19 *** data will be needed to enlighten all aspects of COVID-19 pathogenesis,before determining the effects of plants on severe acute respiratory syndrome coronavirus 2.

关键词： COVID-19 Herbal therapies Plant SARS-CoV-2 Antiviral Symptom

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Structure,Properties and Behavior of Kyanite:Use in Refractory Monolithics

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China's Refractories 2003年第3期12卷 3-6页

作者： Musa karakus Robert Moore Department of Ceramic Engineering University of Missouri-RollaDepartment of Ceramic EngineeringUniversity of Missouri-Rolla

1 Introduction Kyanite is an important naturally occurring in-dustrial mineral and is used in the manufacture of avariety of industrial ceramic products; notable exam-ples include refractories and porcelains. It is a high-pressure polymorph of the aluminosilicates of the ne-sosilicate group, which includes kyanite, sillimanite,and andalusite. These three aluminous or alumina-rich minerals are chemically identical with the compo-sition, Al;SiO;, but have different crystal structuresand physical properties. It is, however, their alumina

关键词： of it or on Structure,Properties and Behavior of Kyanite in

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