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Reinforcement selection for deep and high-stress tunnels at preliminary design stages using ground demand and support capacity approach

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International Journal of Mining Science and Technology 2018年第4期28卷 571-580页

作者： Reza Masoudi mostafa sharifzadeh Department of Mining&Metallurgical Engineering Curtin University Western Australian School of Mines(WASM)Perth 6102Australia

Underground mining is going to be deeper gradually because near surface resources are going to be depleted. Therefore, risk of seismic events in underground mines is escalating. Additionally, existence of the large ratio of horizontal to vertical stress, could be a potential reason for high-stress condition and occurrence of dynamic activities. Depending on various parameters such as the level of induced stress, rock properties, etc., ground demand changes and it is difficult to estimate. On the other hand,under seismic condition, energy dissipation and deformation capacity of supports is the most important factors, however, rock support performance factors in dynamic conditions are still under *** the knowledge of reinforcement behaviour and capacity, specifically that of the rockbolt as a primary element in seismic conditions, would help to develop a suitable, safe and economic support design. This paper contains various methods to estimate ground demand including the intact rock properties approach, failure thickness and ejection velocity estimation, and rockburst damage potential method. It also covers measurement methods of rockbolts energy dissipation capacities such as drop test,blasting simulating, back calculation and momentum transfer measurement methods. A large-scale dynamic test rig is also explained. Based on the findings, a table and a graph to show the applicable range of each type of rockbolts were presented. Suitable rockbolt types for various ground energy demand and deformation capacity range were categorised in the table and the graph. The presented support selection method facilitates the selection of a suitable reinforcement system at the preliminary stages of design and guides the designer to adjust the support reinforcement system based on observed ground and support reaction.

关键词： High-stress tunnels Support system Ground demand Reinforcement capacity Rockbolt

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Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations

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International Journal of Mining Science and Technology 2019年第3期29卷 409-418页

作者： Reza Masoudi mostafa sharifzadeh Masoud Ghorbani Department of Mining & Metallurgical Engineering Curtin UniversityWestern Australian School of Mines (WASM)Australia Department of Mining Metallurgy and Petroleum EngineeringAmirkabir University of Technology (Tehran Polytechnic)TehranIran

Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground *** encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility,cost effectiveness and easy *** elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity,knowing that the former is more *** other words,achieving early stiff behaviour along with large deformation capacity in rockbolts are the goals for new development in rock *** rockbolts are expensive while some of them have large deformation capability with low ultimate load *** this paper,modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic *** a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground,improves the deformation capacity of the ***,leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of *** the dynamic performance of the bolt is improved by these easily applicable *** behaviour and performance of encapsulated rockbolts have been discussed first,then the effects of modifications are *** proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.

关键词： Rockbolt Tunnel support Collar bonding Seismic rock support Tunnelling

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A method for extracting anomaly map of Au and As using combination of U-statistic and Euclidean distance methods in Susanvar district,Iran

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Journal of Central South University 2017年第11期24卷 2693-2704页

作者： Seyyed Saeed Ghannadpour Ardeshir Hezarkhani mostafa sharifzadeh Department of Mining & Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic) Department of Mining Engineering and Metallurgical Engineering Western Australia School of MineCurtin University

Quantitative descriptions of geochemical patterns and providing geochemical anomaly map are important in applied geochemistry. Several statistical methodologies are presented in order to identify and separate geochemical anomalies. The U-statistic method is one of the most important structural methods and is a kind of weighted mean that surrounding points of samples are considered in U value determination. However, it is able to separate the different anomalies based on only one variable. The main aim of the presented study is development of this method in a multivariate mode. For this purpose, U-statistic method should be combined with a multivariate method which devotes a new value to each sample based on several variables. Therefore, at the first step, the optimum p is calculated in p-norm distance and then U-statistic method is applied on p-norm distance values of the samples because p-norm distance is calculated based on several variables. This method is a combination of efficient U-statistic method and p-norm distance and is used for the first time in this research. Results show that p-norm distance of p=2(Euclidean distance) in the case of a fact that Au and As can be considered optimized p-norm distance with the lowest error. The samples indicated by the combination of these methods as anomalous are more regular, less dispersed and more accurate than using just the U-statistic or other nonstructural methods such as Mahalanobis distance. Also it was observed that the combination results are closely associated with the defined Au ore indication within the studied area. Finally, univariate and bivariate geochemical anomaly maps are provided for Au and As, which have been respectively prepared using U-statistic and its combination with Euclidean distance method.

关键词： mineral anomaly Susanvar district U-statistic method Euclidean distance bivariate anomaly map

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A critical review on the developments of rock support systems in high stress ground conditions

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International Journal of Mining Science and Technology 2020年第5期30卷 555-572页

作者： Masoud Ghorbani Korosh Shahriar mostafa sharifzadeh Reza Masoudi Department of Mining and Metallurgical Engineering Amirkabir University of TechnologyTehranIran Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyangLiaoning 110819China Department of Mining and Metallurgical Engineering Curtin UniversityKalgoorlieWA 6430Australia

Extreme ground behaviour in high-stress rock masses such as rockburst prone and squeezing ground conditions are encountered in a range of underground projects both in civil and mining *** occurrence of such ground behaviour types are difficult to predict and special design and construction measures must be taken to control *** the most appropriate support system in such grounds is one of the major challenges for ground control engineers because there are many contributing factors to be considered,such as the rock mass parameters,the stress condition,the type and performance of the support systems,the condition of major geological structures and the size and geometry of the underground *** main characteristics and support requirements of rockburst-prone and squeezing ground conditions are herein critically reviewed and characteristics of support functions are *** types of energy-absorbing rockbolts and other support elements applicable for ground support in burst-prone and squeezing grounds are *** differences in the choice and economics of ground support strategies in high-stress ground conditions between civil tunnels and mining excavations are *** support benchmarking data and mitigation measures for mines and civil tunnels in burst-prone,squeezing and heavily swelling grounds conditions are briefly presented by some examples in practice.

关键词： High in-situ stress Rockburst Squeezing Swelling Energy-absorbing rockbolts Yielding supports

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Ground behaviour analysis,support system design and construction strategies in deep hard rock mining-Justified in Western Australian’s mines

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 1-20页

作者： Behrooz Rahimi mostafa sharifzadeh Xia-Ting Feng Department of Mining and Metallurgical Engineering Western Australian School of Mines:MineralsEnergy and Chemical Engineering(WASM-MECE)Curtin UniversityKalgoorlieWM6430Australia Key Laboratory of Ministry of Education for Safe Mining of Deep Metal Mines Northeastern UniversityShenyang110819China

Development of deep underground mining projects is crucial for optimum extraction of mineral *** main challenges at great depth are high rock stress levels,seismic events,large-scale deformation,sudden failures and high temperatures that may cause abrupt and unpredictable instability and collapse over a large *** this paper,a ground control and management strategy was presented corresponding to the three stages of projects:strategic design,tactical design and operational *** design is results in preparing a broad plan and primary design for mining *** tactical design is to provide detail design such as stabilisation *** design stage is related to monitoring and updating design *** most effective ground control strategies in this stage are maintenance,rehabilitation,monitoring and contingency ***,a new procedure for design of ground support systems for deep and hard rock was *** main principles are:static and/or dynamic loading types,determination of loading sources,characterisation of geological conditions and the effects of orientation of major structures with openings,estimation of ground loading factor,identification of potential primary and secondary failures,utilisation of appropriate design analysis methods,estimation of depth failure,calculation of the static and/or dynamic demand ground support capacity,and selection of surface and reinforcement *** force is the dominant loading force in low-level *** high stress level failure mechanism becomes more complex in rock mass *** this condition,a variety of factors such as release of stored energy due to seismic events,stress concentration,and major structures influence on ground behaviour and judgement are very *** key rock engineering schemes to minimise the risk of failures in high-stress levels at great depth involve depressurisation and quality control of ***

关键词： Ground management Support system design Sequential excavation Stress management Geotechnical monitoring Deep underground mines

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Effect of dynamic loading conditions on the dynamic performance of MP1 energy-absorbing rockbolts:Insight from laboratory drop test

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International Journal of Mining Science and Technology 2023年第2期33卷 215-231页

作者： Jinfu Lou Fuqiang Gao Jianzhong Li Guiyang Yuan mostafa sharifzadeh CCTEG Coal Mining Research Institute Beijing 100013China State Key Laboratory of Coal Mining and Clean Utilization Beijing 100013China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 110819China

Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.

关键词： Energy-absorbing rockbolt Dynamic performance Drop test Residual elastic energy(REE) Energy absorption rate(EAR) Dynamic capacity envelope

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Role of stress,slenderness and foliation on large anisotropic deformations at deep underground excavations

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International Journal of Mining Science and Technology 2021年第4期31卷 577-590页

作者： Bo Hu mostafa sharifzadeh Xiating Feng Wenbin Guo Roo Talebi State Key Laboratory of Mountain Bridge and Tunnel Engineering School of Civil EngineeringChongqing Jiaotong UniversityChongqing 400074China Northern Star Resources Ltd. KalgoorlieWA 6430Australia Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 110819China Engineering Research Centre for the Safe Exploitation and Comprehensive Utilization of Mineral Resources at Universities of Inner Mongolia Hulunbuir UniversityHulunbuir 021008China Western Australian School of Mines(WASM) Curtin UniversityKalgoorlieWA 6430Australia

High stress concentrations around underground excavations can result in significant damage to deep hard-rock *** conditions can be the result of stopping activities,blasting,seismicity,or other mining *** anisotropic deformation and excavation closure,especially under high-stress conditions,are expected if the excavation is located in a foliated or thin-bedded rock *** this research,the behaviour of excavations under deep and high-stress conditions was investigated and *** main purpose was to enhance the existing knowledge of managing large anisotropic deformations and to help prepare suitable measures for handling such *** simulations using the distinct element method(DEM)and model calibration were performed to reproduce the anisotropic deformation of an ore drive based on the collected field ***,the roles of key factors(*** ratio,slenderness ratio,foliation orientation,and foliation considering excavation orientation)on the large deformation and damage depth of the excavations were *** study found that increasing both the stress ratio and slenderness ratio induced linear increases in wall closure and damage depth,whereas increasing the foliation angle first increases the deformation and damage depth and then reduces them both before and after 45.The wall closure and damage thickness decreased with increasing orientation *** deformation and damage levels were classified based on these factors.

关键词： Large anisotropic deformation Buckling Deep mining Slenderness ratio Intercept angle Foliation orientation

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Application of artificial neural networks and multivariate statistics to estimate UCS using textural characteristics

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International Journal of Mining Science and Technology 2012年第2期22卷 229-236页

作者： Amin Manouchehrian mostafa sharifzadeh Rasoul Hamidzadeh Moghadam Department of Mining Engineering Sahand University of TechnologyTabrizIran Department of Mining Metallurgy and Petroleum EngineeringAmirkabir University of TechnologyTehranIran

Before any rock engineering project,mechanical parameters of rocks such as uniaxial compressive strength and young modulus of intact rock get measured using laboratory or in-situ tests,but in some situations preparing the required specimens is *** this time,several models have been established to evaluate UCS and E from rock substantial *** neural networks are powerful tools which are employed to establish predictive models and results have shown the priority of this technique compared to classic statistical *** this paper,ANN and multivariate statistical models considering rock textural characteristics have been established to estimate UCS of rock and to validate the responses of the established models,they were compared with laboratory *** this purpose a data set for 44 samples of sandstone was prepared and for each sample some textural characteristics such as void,mineral content and grain size as well as UCS were *** select the best predictors as inputs of the UCS models,this data set was subjected to statistical analyses comprising basic descriptive statistics,bivariate correlation,curve fitting and principal component *** of such analyses have shown that void,ferroan calcitic cement,argillaceous cement and mica percentage have the most effect on *** predictive models for UCS were developed using these variables by ANN and linear multivariate *** have shown that by using simple textural characteristics such as mineral content,cement type and void,strength of studied sandstone can be estimated with acceptable *** and multivariate statistical UCS models,revealed responses with 0.87 and 0.76 regressions,respectively which proves higher potential of ANN model for predicting UCS compared to classic statistical models.

关键词： Textural characteristicsUniaxial compressive strengthPredictive modelsArtificial neural networksMultivariate statistics

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Analytical computation of support characteristic curve for circumferential yielding lining in tunnel design

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 144-152页

作者： Kui Wu Zhushan Shao mostafa sharifzadeh Siyuan Hong Su Qin School of Science Xi’an University of Architecture and TechnologyXi’an710055China Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering(XAUAT) Xi’an University of Architecture and TechnologyXi’an710055China Department of Mining and Metallurgical Engineering Western Australian School of MinesCurtin UniversityKalgoorlie6430Australia

Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing ***,up to now,there has not been a well-established design method for *** paper aims to present a detailed analytical computation of support characteristic curve(SCC)for circumferential yielding lining,which is a significant aspect of the implementation of convergence-confinement method(CCM)in tunnel support *** yielding lining consists of segmental shotcrete linings and highly deformable elements,and its superior performance mainly depends on the mechanical characteristic of highly deformable *** deformation behavior of highly deformable element is firstly *** whole deforming process can be divided into three stages including elastic,yielding and compaction *** in the compaction stage of highly deformable element,a nonlinear stress-strain relationship can be *** mathematical convenience,the stress-strain curve in this period is processed as several linear ***,the reasons for closure of circumferential yielding lining in different stages are explained,and the corresponding accurate equations required for constructing the SCC are ***,this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining,where the reliability and feasibility of theoretical derivation are also well ***,this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on *** outcome of this paper could be used in the design of proper circumferential yielding lining.

关键词： Squeezing ground Circumferential yielding lining Highly deformable element Support characteristic curve(SCC) Analytical method

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Selection of regression models for predicting strength and deformability properties of rocks using GA

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International Journal of Mining Science and Technology 2013年第4期23卷 492-498页

作者： Manouchehrian Amin sharifzadeh mostafa Hamidzadeh Moghadam Rasoul Nouri Tohid Mining Engineering Department Sahand University of Technology Department of Mining and Metallurgical Engineering Amirkabir University of Technology Department of Mining Engineering Western Australian School of minesCurtin University

Recently,many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index *** statistical analysis is a common method for developing regression models,but still selection of suitable transformation of the independent variables in a regression model is *** this paper,a genetic algorithm(GA)has been employed as a heuristic search method for selection of best transformation of the independent variables(some index properties of rocks)in regression models for prediction of uniaxial compressive strength(UCS)and modulus of elasticity(E).Firstly,multiple linear regression(MLR)analysis was performed on a data set to establish predictive ***,two GA models were developed in which root mean squared error(RMSE)was defned as ftness *** have shown that GA models are more precise than MLR models and are able to explain the relation between the intrinsic strength/elasticity properties and index properties of rocks by simple formulation and accepted accuracy.

关键词： Regression models Genetic algorithms Heuristics Uniaxial compressive strength Modulus of elasticity Rock index property

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