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| 1 | Experimental study on dynamic mechanical property of cemented tailings backfill under SHPB impact loading显示文摘Cemented tailings backfill(CTB) have increasingly been used in recent years to improve the stability of mining stopes in deep underground mines. Deep mining processes are often associated with rock bursting and high-speed dynamic loading conditions. Therefore, it is important to investigate the characteristics and dynamic mechanical behavior of CTB. This paper presents the results of dynamic tests on CTB specimens with different cement and solid contents using a split Hopkinson pressure bar(SHPB). The results showed that some CTB specimens exhibited one to two lower stress peaks after reaching dynamic peak stress before they completely failed. The greater the cement-to-tailings ratio is, the more obvious the strain reaction. This property mainly manifested as follows. First,the dynamic peak stress increased with the increase of the cement-to-tailings ratio when the impact velocity was fixed. Second, the dynamic peak stress had a quadratic relationship with the average stress rate. Third, the cement-to-tailings ratio could enhance the increase rate of dynamic peak stress with strain rate. In addition, the dynamic strength enhancement factor K increased with the increase of strain rate, and its value was larger than that of the rock samples. The failure modes of CTB specimens under low-speed impact were tensile failure and X conjugate shear failure, where were nearly the same as those under static uniaxial and triaxial compression. The CTB specimens were crushed and broken under critical strain, a failure mode similar to that of low-strength concrete. The results of the experimental research can improve the understanding of the dynamic mechanical properties of CTB and guide the strength design of deep mining backfills. | Yu-ye Tan Xin Yu Davide Elmo Lin-hui Xu Wei-dong Song | 2019 | International Journal of Minerals,Metallurgy and Materials2019，26，4： | 19 |
| 2 | Overhanging rock slope by design:An integrated approach using rock mass strength characterisation,large-scale numerical modelling and limit equilibrium methods显示文摘Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope. | Paul Schlotfeldt Davide Elmo Brad Panton | 2018 | Journal of Rock Mechanics and Geotechnical Engineering2018，10，1： | 8 |
| 3 | Modelling of blast-induced damage in tunnels using a hybrid finite-discrete numerical approach显示文摘This paper presents the application of a hybrid finite-discrete element method to study blast-induced damage in circular tunnels. An extensive database of field tests of underground explosions above tunnels is used for calibrating and validating the proposed numerical method; the numerical results are shown to be in good agreement with published data for large-scale physical experiments. The method is then used to investigate the influence of rock strength properties on tunnel durability to withstand blast loads. The presented analysis considers blast damage in tunnels excavated through relatively weak(sandstone) and strong(granite) rock materials. It was found that higher rock strength will increase the tunnel resistance to the load on one hand, but decrease attenuation on the other hand. Thus, under certain conditions, results for weak and strong rock masses are similar. | Amichai Mitelman Davide Elmo | 2014 | Journal of Rock Mechanics and Geotechnical Engineering2014，6，6： | 7 |
| 4 | Characterizing the influence of stress-induced microcracks on the laboratory strength and fracture development in brittle rocks using a finite-discrete element method-micro discrete fracture network FDEM-μDFN approach显示文摘Heterogeneity is an inherent component of rock and may be present in different forms including mineral heterogeneity,geometrical heterogeneity,weak grain boundaries and micro-defects.Microcracks are usually observed in crystalline rocks in two forms:natural and stress-induced;the amount of stressinduced microcracking increases with depth and in-situ stress.Laboratory results indicate that the physical properties of rocks such as strength,deformability,P-wave velocity and permeability are influenced by increase in miciocrack intensity.In this study,the finite-discrete element method(FDEM)is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks using the proposed micro discrete fracture network(μDFN) approach.The characteristics of the microcracks required to create μDFN models are obtained through image analyses of thin sections of Lac du Bonnet granite adopted from published literature.A suite of two-dimensional laboratory tests including uniaxial,triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data.The FDEM-μDFN models indicate that micro-heterogeneity has a profound influence on both the mechanical behavior and resultant fracture pattern.An increase in the microcrack intensity leads to a reduction in the strength of the sample and changes the character of the rock strength envelope.Spalling and axial splitting dominate the failure mode at low confinement while shear failure is the dominant failure mode at high confinement.Numerical results from simulated compression tests show that microcracking reduces the cohesive component of strength alone,and the frictional strength component remains unaffected.Results from simulated Brazilian tests show that the tensile strength is influenced by the presence of microcracks,with a reduction in tensile strength as microcrack intensity increases.The importance of microcrack heterogeneity in reproducing a bi-linear or S-shape failure envelope and its effects on the mechanisms leading to spalling damage near an underground opening are also discussed. | Pooya Hamdi Doug Stead Davide Elmo | 2015 | Journal of Rock Mechanics and Geotechnical Engineering2015，7，6： | 6 |
| 5 | Long-term mechanical behavior and characteristics of cemented tailings backfill through impact loading显示文摘Cemented tailings backfill(CTB)structures are important components of underground mine stopes.It is important to investigate the characteristics and dynamic behavior of CTB materials because they are susceptible to disturbance by dynamic loading,such as excavation and blasting.In this study,the authors present the results of a series of Split-Hopkinson pressure bar(SHPB)single and cyclic impact loading tests on CTB specimens to investigate the long-term dynamic mechanical properties of CTB.The stress-strain relationship,dynamic strength,and dynamic failure characteristics of CTB specimens are analyzed and discussed to provide valuable conclusions that will improve our knowledge of CTB long-term mechanical behavior and characteristics.For instance,the dynamic peak stress under cyclic impact loading is approximately twice that under single impact loading,and the CTB specimens are less prone to fracture when cyclically loaded.These findings and conclusions can provide a new set of references for the stability analysis of CTB materials and help guide mine designers in reducing the amount of binding agents and the associated mining cost. | Yu-ye Tan Elmo Davide Yu-cheng Zhou Wei-dong Song Xiang Meng | 2020 | International Journal of Minerals,Metallurgy and Materials2020，27，2： | 6 |
| 6 | 高水力条件下深部砂岩的强度与储能交互特征显示文摘为了研究围压和孔隙水压对深部砂岩强度特征、储能状态和峰值破坏时能量释放烈度的影响规律,开展一系列水力耦合条件下的三轴压缩试验。通过分析岩石变形破坏过程,获得其应力阈值。利用图形积分方法获得深部砂岩在峰前阶段总能量密度、弹性能量密度、耗散能量密度的变化趋势。对比不同围压下岩石的动态储能水平,分析孔隙水压对岩石闭合应力、起裂应力、损伤应力、峰值应力等应力阈值处能量耗散的影响。基于峰前、后总能量密度的比值,研究围压与孔隙水压对深部砂岩岩爆倾向性的相互作用机理。实验结果表明,砂岩峰值应力随着围压的增加而增加,而孔隙水压的存在可以削弱砂岩的峰值应力。在自闭合应力至峰值应力间的应力阶段,岩石的动态储能水平呈现出反“对勾”的演化趋势。同时随着围压的增加,动态储能水平上升。然而,孔隙水压增大岩石的能量耗散程度,降低岩石的储能能力,耗散程度与孔隙水压呈线性关系。围压的增大加剧深部砂岩的失稳破坏现象,而孔隙水压具有相反作用。研究成果将为高应力、高孔隙水压下砂岩地层工程岩体开挖稳定性分析提供有力的数据支撑。 | 李飞 由爽 纪洪广 ELMO Davide 王洪涛 | 2020 | Journal of Central South University2020，27，10： | 4 |
| 7 | 基于“中外教师组合”的采矿工程专业英语教学探索显示文摘中国矿业大学采矿工程专业近年来开展了专业英语中外教师结合教学的探索研究工作。本文介绍了'现代采矿技术'双语课程的教学目标与定位,以拓宽国际化视野、强化基础知识、提高国际交流能力为出发点的课程教学内容。结合以往双语课程开设及讲授的经验,提出了中外教师相结合、以渐进型为主和'两点一线'式的课程教学模式,最终使学生成为基础知识扎实且具有国际视野和国际交流能力的国际采矿人。 | 闫帅 李桂臣 Davide Elmo 阚甲广 | 2018 | 科教文汇2018，，13： | 4 |
| 8 | Development of a spring analogue approach for the study of pillars and shafts显示文摘In civil and mining operations that involve ground excavation and support, the loads are distributed between the ground and support depending on their relative stiffness. This paper presents the development of conceptual single-degree-of-freedom models, which are used to derive equations for estimating displacements and stresses for ground-support interaction problems encountered in pillars in room-andpillar mining(natural support system), and liners for circular vertical shafts(artificial support systems).For pillar assessment, mine-pillar interaction curves can be constructed using a double spring analogy.Additionally, the effectiveness of different support systems can be evaluated depending on their effect upon the mine-pillar system. For shaft design, an initial estimation of the required lining strength and thickness can be readily made based on a double ring analogue. For both problems, the results from the proposed approach compare well with those obtained by finite element numerical simulations. | Amichai Mitelman Davide Elmo Doug Stead | 2018 | International Journal of Mining Science and Technology2018，28，2： | 2 |
| 9 | 切近位关键层卸压沿空掘巷关键参数与工程应用显示文摘以马家岩煤矿40103回风巷(沿空掘巷)为背景,采用理论分析、数值模拟和工程实践等方法研究切顶卸压沿空掘巷关键参数等问题。结果表明:关键层位于4~8倍采高范围时为近位关键层,位于4~8倍采高范围外时为远位关键层;掘进期间在块体A(悬臂结构)下完成;切角垂直于顶板时卸压效果最好,有利于岩块C_(i)的滑落,但倒梯形切顶结构更有利于超前巷道顶板稳定,选取75°为切顶角度;切顶长度越深卸压效果越好,超过关键层后,再增加切长,支承压力继续降低但降低幅度逐渐减小。通过对比切顶(切长20 m,角度75°)与不切顶条件下不同煤柱宽度支承压力,可发现:实体煤侧支承压力依然呈“单峰”状分布,大煤柱(>10 m)上支承压力呈非对称“马鞍”状分布,小煤柱(<10 m)支承压力呈“钟形”分布,切顶可降低支承压力峰值,但不改变其位置。炮孔间距不大于爆破裂隙损伤半径的2倍,可根据现场及时调整。最终确定护巷煤柱宽度8 m,切顶长度20 m,角度75°,炮孔间距1.0 m,支护方案为锚杆+金属网+钢带+锚索补强联合支护。掘进期间两帮相对位移量156 mm,顶板下沉量186 mm,底鼓量101 mm;10 d左右实现自稳;回采期间两帮相对最大移近速度42 mm/d,顶板最大下沉速度47 mm/d,底鼓最大速度63 mm/d。 | 许磊 李明伟 郭亮 肖同强 刘洪林 DAVIDE Elmo | 2023 | 采矿与安全工程学报2023，40，1： | 2 |
| 10 | Influence of data analysis when exploiting DFN model representation in the application of rock mass classification systems显示文摘Discrete fracture network(DFN) models have been proved to be effective tools for the characterisation of rock masses by using statistical distributions to generate realistic three-dimensional(3 D) representations of a natural fracture network. The quality of DFN modelling relies on the quality of the field data and their interpretation. In this context, advancements in remote data acquisition have now made it possible to acquire high-quality data potentially not accessible by conventional scanline and window mapping. This paper presents a comparison between aggregate and disaggregate approaches to define fracture sets, and their role with respect to the definition of key input parameters required to generate DFN models. The focal point of the discussion is the characterisation of in situ block size distribution(IBSD) using DFN methods. An application of IBSD is the assessment of rock mass quality through rock mass classification systems such as geological strength index(GSI). As DFN models are becoming an almost integral part of many geotechnical and mining engineering problems, the authors present a method whereby realistic representation of 3 D fracture networks and block size analysis are used to estimate GSI ratings, with emphasis on the limitations that exist in rock engineering design when assigning a unique GSI value to spatially variable rock masses. | Takako Miyoshi Davide Elmo Steve Rogers | 2018 | Journal of Rock Mechanics and Geotechnical Engineering2018，10，6： | 1 |
| 11 | Role of rock mass fabric and faulting in the development of block caving induced surface subsidence 显示文摘 | Alexander Vyazmensky Davide Elmo Douglas Stead | 2010 | Rock Mech Rock Eng2010，43，： | 1 |
| 12 | 深部不同断面巷道分区破裂形态与围岩结构控制显示文摘采用理论分析、现场实测、模拟分析的方法,研究了各向等压条件下等效开挖矩形、直墙半圆拱和圆形断面分区破裂形态及围岩稳定结构。结论:3个断面分区破裂形态不同,矩形断面分区破裂呈“■”状分布,直墙半圆拱断面分区破裂呈多层的“■”状分布,圆形断面分区破裂呈“花瓣”状分布;三个断面位移特征相似,位移等值线浅部呈正立的“鸡蛋壳”形,深部呈“碗”形;支承压力在主破裂面处降低,在最外层主破裂面头部集中,在破裂面之间完整岩层处升高,呈分区集中,“波谷—波峰—波谷”震荡增高的特征向外传播;理想正方形破裂面弦长有an+1=2(1/2)an(n=1,2,3,4)关系;浅部围岩分区破裂形成后,相当于深部围岩的伪开挖,3个断面均存在多层“■”形围岩承载结构。巷道稳定原理就是促进多层承载结构相互依存,共同承载。具体措施:加密、加粗、加长锚杆(索)支护结构,建立浅部与深部多层承载结构相互联系,在浅部形成稳定锚固体促进深部围岩稳定,主破裂面精准注浆修复围岩破裂面和限制主破裂面滑移。 | 许磊 郭帅 Davide Elmo 刘洪林 洪紫杰 肖同强 | 2023 | 岩土工程学报2023，45，4： | 0 |
| 13 | 矸石充填体机械压缩过程及宽条带岩层沉降分析显示文摘以亭南煤矿1102宽条带矸石充填工作面为工程背景,采用理论分析、数值模拟、室内试验、现场实测等方法研究了矸石机械压缩过程及岩层沉降规律。结果表明:散体矸石经2 MPa夯实后压缩了27.05%,变成矸石充填体,矸石充填体在可充填空间内机械压缩过程及架后压缩率为(各阶段压缩与可充填空间高度比值):骨架调整段(7.42%),缓慢压缩段(5.39%);机械压缩等价采高为可充填空间高度与矸石充填体2个阶段可充压缩率的乘积;1102工作面矸石充填体在骨架调整段和缓慢压缩段的等价采高分别为0.94 m和1.10 m;1102工作面走向和倾向主断面地表下沉曲线均为“碗”形,骨架调整段到缓慢压缩段过程中,地表变形曲线变化不大,最终最大下沉量分别为39 mm和41 mm。 | 轩召军 许磊 相峥 蔡玲祥 郭帅 DAVIDE Elmo | 2024 | 煤矿安全2024，55，2： | 0 |
| 14 | New approaches to quantify progressive damage and associated dynamic rock mass blockiness显示文摘In the past decade, numerical modelling has been increasingly used for simulating the mechanical behaviour of naturally fractured rock masses. In this paper, we introduce new algorithms for spatial and temporal analyses of newly generated fractures and blocks using an integrated discrete fracture network (DFN)-finite-discrete element method (FDEM) (DFN-FDEM) modelling approach. A fracture line calculator and analysis technique (i.e. discrete element method (DEM) fracture analysis, DEMFA) calculates the geometrical aspects of induced fractures using a dilation criterion. The resultant two-dimensional (2D) blocks are then identified and characterised using a graph structure. Block tracking trees allow track of newly generated blocks across timesteps and to analyse progressive breakage of these blocks into smaller blocks. Fracture statistics (number and total length of initial and induced fractures) are then related to the block forming processes to investigate damage evolution. The combination of various proposed methodologies together across various stages of modelling processes provides new insights to investigate the dependency of structure's resistance on the initial fracture configuration. | Ladan Karimi Sharif Davide Elmo Doug Stead | 2023 | Journal of Rock Mechanics and Geotechnical Engineering2023，15，2： | 0 |
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