检索结果-南通市图书馆

International Journal of Coal Science & Technology 2024年第2期11卷 53-66页

作者： Parviz Enany Carsten Drebenshtedt faculty of mining and special civil engineering Technische Universitat BergakademieGustav-Zeuner StraBe 1A09599FreibergGermany

In this study,the installation of an airlift pump with inner diameter of 102 mm and length of 5.64 m was utilized to consider the conveying process of non-spherical coal particles with density of 1340 kg/m3 and graining 25-44.5 *** test results revealed that the magnitude of increase in the solid transport rate due to the changes in the three tested parameters between compressed air velocity,submergence ratio,and feeding coal possibility was not the same,which are stand in range of 20%,75%,and 40%,***,creating the optimal airlift pump performance is highly dependent on submergence *** importantly,we measured the solid volume fraction using the method of one-way valves in order to minimize the disadvantages of conventional devices,such as fast speed camera and conductivity ring *** results confirmed that the volume fraction of the solid phase in the transfer process was always less than 12%.To validate present experimental data,the existing empirical correlations together with the theoretical equations related to the multiphase flow was *** overall agreement between the theory and experimental solid delivery results was particularly good instead of the first stage of conveying *** drawback can be corrected by omitting the role of friction and shear stress at low air income *** was also found that the model developed by Kalenik failed to predict the performance of our airlift operation in terms of the mass flow rate of the coal particles.

关键词： Vertical velocity Non-spherical particle Submergence ratio Three-phase flow Churn flow Superficial velocity

Quasi-static and dynamic compressive behaviour of additively manufactured Menger fractal cube structures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第7期37卷 39-49页

作者： Damith Mohotti Dakshitha Weerasinghe Madhusha Bogahawaththa Hongxu Wang Kasun Wijesooriya Paul JHazell School of engineering and Technology UNSWCanberraACT2600Australia School of civil Mining and Environmental EngineeringFaculty of Engineering and Information SciencesUniversity of WollongongWollongongNSWAustralia

This paper presents the first-ever investigation of Menger fractal cubes'quasi-static compression and impact *** cubes with different void ratios were 3D printed using polylactic acid(PLA)with dimensions of 40 mm×40 mm×40 *** different orders of Menger cubes with different void ratios were considered,namely M1 with a void ratio of 0.26,M2 with a void ratio of 0.45,and M3with a void ratio of ***-static Compression tests were conducted using a universal testing machine,while the drop hammer was used to observe the behaviour under impact *** fracture mechanism,energy efficiency and force-time histories were *** the structured nature of the void formation and predictability of the failure modes,the Menger geometry showed some promise compared to other alternatives,such as foams and *** the increasing void ratio,the Menger geometries show force-displacement behaviour similar to hyper-elastic materials such as rubber and *** third-order Menger cubes showed the highest energy absorption efficiency compared to the other two geometries in this *** findings of the present work reveal the possibility of using additively manufactured Menger geometries as an energy-efficient system capable of reducing the transmitting force in applications such as crash barriers.

关键词： Additive manufacturing Fractal geometries Menger cube Energy absorption Quasi-static

Study on the tunnel shape and soil-lining interaction influencing the lining behavior under seismic loading

在线全文

学校读者我要写书评

暂无评论

Earthquake engineering and engineering Vibration 2024年第4期23卷 845-862页

作者： Van Vi Pham Ngoc Anh Do Piotr Osinski Ngoc Thai Do Daniel Dias Sustainable Development in Underground engineering Research Team Hanoi University of Mining and GeologyHanoiVietnam Department of Underground and mining Construction Faculty of Civil EngineeringHanoi University of Mining and GeologyHanoiVietnam Department of Geotechnical engineering Institute of Civil EngineeringWarsaw University of Life Sciences-SGGWWarszawaPoland Laboratory 3SR Grenoble Alpes UniversityGrenoble 38400France

The response of tunnels subjected to seismic loading is a complex mechanism and depends not only on the seismic nature but also on tunnel structure and surrounding soil *** individual behavior of circular,rectangular,and sub-rectangular tunnels subjected to seismic loadings has already been studied in the *** the present research,two case scenarios of circular,rectangular tunnels and four sub-rectangular shaped tunnels,with similar cross-section areas,were adopted to perform a comprehensive numerical *** purpose of the study was to determine the mechanical behavior of tunnels of different shapes,depending upon seismic *** were performed by considering the influence of soil-lining interaction,soil parameters,and lining thickness,as well as lining *** were performed for no-slip and full-slip *** results indicate that the tunnel shape design is of great importance when regarding the mechanical behavior of the surrounding *** concerns no-slip as well as full-slip soil-lining interaction,especially when the lining is subjected to seismic ***,it is shown that changes in incremental bending moments for circular,rectangular and sub-rectangular tunnels that depend upon the soil-lining interaction conditions differ significantly.

关键词： tunnel shape soil-lining interaction seismic loading internal forces numerical analysis

Goaf risk prediction based on IAOA-SVM and numerical simulation:A case study

在线全文

学校读者我要写书评

暂无评论

Underground Space 2024年第2期15卷 153-175页

作者： Mingliang Li Kegang Li Yuedong Liu Shunchuan Wu Qingci Qin Rui Yue faculty of Land Resources engineering Kunming University of Science and TechnologyKunming 650093China Yunnan Key Laboratory of Sino-German Blue mining and Utilization of special Underground Space Kunming 650093China Yunnan Diqing mining Co.Ltd. Shangrila 674400China

In regard to goaf risk prediction,due to the low accuracy and single prediction method,this study proposes a method that combines the improved arithmetic optimization algorithm(IAOA)–support vector machines(SVM)with GoCAD–FLAC^(3D)numerical ***,goaf risk is comprehensively *** the perspectives of geological and engineering conditions,eight factors that affect goaf stability and 176 sets of sample data were *** utilized eight influencing factors such as rock mass structure,geological structure,and goaf burial depth as inputs,and the goaf risk level as the ***,an IAOA–SVM goaf risk prediction model was *** 30 goaf areas of Yangla Copper Mine in Yunnan Province were selected as the research ***,the rationality of mechanical parameter values in the numerical model was verified using the parameter inversion ***,based on the GoCAD–FLAC^(3D)numerical simulation method,the goaf risk analysis in Yangla Copper Mine was ***,using numerical simulation verification,the goaf filling effect was ***,the prediction results of the IAOA–SVM model were compared with that of other intelligent *** results indicate that the numerical simulation results of the GoCAD–FLAC^(3D)model are consistent with those of IAOA–SVM and the actual results,which further verifies the effectiveness and superiority of the IAOA–SVM prediction ***,an innovative approach for goaf risk prediction is developed.

关键词： Rock mechanics Goaf risk prediction IAOA SVM Numerical simulation

Sliding behaviors of the trapezoidal roof rock block under a lateral dynamic disturbance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第3期16卷 741-760页

作者： Feng Dai Wancheng Zhu Min Ren Shunchuan Wu Leilei Niu faculty of Land Resources engineering Kunming University of Science and TechnologyKunming650093China Center for Rock Instability and Seismicity Research Department of Mining EngineeringSchool of Resource and Civil EngineeringNortheastern UniversityShenyang110819China

The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A series of laboratory tests,numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral ***,the experiments on trapezoidal key block under various clamping loads and disturbance were conducted,followed by numerical simulations using the fast Lagrangian analysis of continua(FLAC3D).Then,based on the conventional wave propagation model and the classical shear-slip constitutive model,a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key *** results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide(without instability).Meanwhile,when the key block was disturbed to fall,two types of instability process may appear as immediate type or delayed *** addition,the propagation of stress waves in the block system exhibited obvious low-velocity and lowfrequency characteristics,resulting in the friction reduction effect appearing at the contact interface,which is the essential reason for the sliding of rock *** results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rockfalling disasters.

关键词： Lateral dynamic disturbance Trapezoidal rock block system Low-velocity and low-frequency wave Friction reduction effect Instability mode

Mechanism of high-preload support based on the NPR anchor cable in layered soft rock tunnels

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第4期21卷 1403-1418页

作者： SUI Qiru HE Manchao SHI Mengfan TAO Zhigang ZHAO Feifei ZHANG Xiaoyu State Key Laboratory for Tunnel engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and civil engineering China University of Mining and Technology(Beijing)Beijing 100083China

The control of large deformation problems in layered soft rock tunnels needs to solve *** roof problem is particularly severe among the deformation issues in *** study first analyzes the asymmetric deformation modes in layered soft rock tunnels with large ***,we construct a mechanical model under ideal conditions for controlling the roof of layered soft rock tunnels through high preload with the support of NPR anchor *** prominent roles of long and short NPR anchor cables in the support system are also *** results indicate the significance of high preload in controlling the roof of layered soft rock *** short NPR anchor cables effectively improve the integrity of the stratified soft rock layers,while the long NPR anchor cables effectively mobilize the self-bearing capacity of deep-stable rock ***,the high-preload support method with NPR anchor cables is validated to have a good effect on controlling large deformations in layered soft rock tunnels through field monitoring data.

关键词： Tunnel engineering Soft rock High-preload support NPR anchor cables

A novel method for simulating nuclear explosion with chemical explosion to form an approximate plane wave: Field test and numerical simulation

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第6期16卷 2137-2153页

作者： Wei Ming Xiaojie Yang Yadong Mao Xiang Wang Manchao He Zhigang Tao College of civil and Architecture engineering North China University of Science and TechnologyTangshan063210China State Key Laboratory for Tunnel engineering China University of Mining and Technology-BeijingBeijing100083China School of Mechanics and civil engineering China University of Mining and Technology-BeijingBeijing100083China

A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection *** the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new *** paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole ***,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was *** plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the *** to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole *** time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear *** comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.

关键词： Approximate plane wave Multi-hole simultaneous blasting Chemical explosion Nuclear explosion Pressure sensor inclusion

Introducing a new rock abrasivity index using a scaled down disc cutter

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第3期3卷 24-37页

作者： Maziar Moradi Mohammad Hossein Khosravi Jafar Khademi Hamidi Department of civil and Environmental engineering University of StrathclydeGlasgowG11XQUK Department of mining engineering Faculty of EngineeringUniversity of BirjandBirjand ***Iran

Rock abrasivity influences wear of cutting tools and consequently,performance of mechanized tunneling *** methods have been proposed to evaluate rock abrasivity in recent decades,each one has its own *** this paper,a new method is introduced to estimate wear of disc cutters based on rock cutting tests using scaled down discs(i.e.54 and 72 mm diameter).The discs are made of H13 steel,which is a common steel type in producing real-scale discs,with hardness of 32 and 54 *** small-scale linear rock cutting machine and a new abrasion test apparatus,namely University of Tehran abrasivity test machine,are utilized to perform the *** width of the worn discs is monitored and presented as the function of the accumulated test run to classify the rock *** tests show that by increasing the uniaxial compressive strength(UCS)of the rock samples,wear rate is doubled gradually that reveals the sensitivity of the test procedure to the main pa-rameters affecting the abrasivity of hard *** the rocks with the highest UCS,the normal wear stops after performing 5 to 10 rounds of the tests,and then,deformation of the disc tip is *** abrasivity indices are defined based on the abrasivity tests results and their correlations with Cerchar Abrasivity Index(CAI)and UCS are *** of the established correlations in this study with previous investigations dem-onstrates the sensitivity of the indices to the parameters affecting wear of the disc cutters and repeatability of the outputs obtained from abrasivity tests using scaled down *** of this study can be used to enhance the accuracy of rock abrasivity classifications.

关键词： Mechanized tunneling Rock cutting Rock abrasivity classification University of Tehran abrasivity test Wear

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical engineering 2024年第5期16卷 1615-1636页

作者： Wendal Victor Yue Siyuan Wu Manchao He Yafei Qiao Zhongqi Quentin Yue Department of Geotechnical engineering College of Civil EngineeringTongji UniversityShanghai200092China Department of civil engineering Faculty of EngineeringThe University of Hong KongPokfulam RoadHong KongChina State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyBeijing100083China Key Laboratory of Geotechnical and Underground engineering of Ministry of Education Tongji UniversityShanghai200092China

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground *** the basis of an actual soil nailing drilling for a slope stability project in Hong Kong,this paper further develops the drilling process monitoring(DPM)method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole(DTH)*** transducers are installed on the drilling machine and record the chuck displacement,DTH rotational speed,and five pressures from five compressed airflows in real-time *** mechanism and operations of the drilling machine are elaborated in detail,which is essential for understanding and evaluating the drilling data.A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time *** processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and *** drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six *** curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering *** effect from fluctuation of the applied pressures is evaluated *** analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock,which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

关键词： Drilling process monitoring(DPM) Down-the-hole(DTH)hammer Percussive-rotary drilling Weathering granitic rocks

DEM investigation of strength and critical state behaviours of granular materials under true triaxial loadings

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2024年第2期85卷 198-212页

作者： Minyi Zhu Guobin Gong Jun Xia Stephen Wilkinson Department of civil engineering Xi'an Jiaotong-Liverpool UniversityChina Department of civil engineering and Industrial Design University of LiverpoolLiverpoolUK faculty of engineering and Information Sciences University of Wollongong in DubaiUnited Arab Emirates

This paper investigates the strength and critical state(CS)behaviours of granular materials via DEM simulations of true triaxial drained tests under three different loading modes including constant b(in-termediate stress ratio)tests with constantσ'1(major principal stress),constant p(mean pressure)and constantσ'3(minor principal stress)*** this end,a series of samples are generated with the same particle size distribution,and with the confining stresses ranging from 100 kPa to 900 *** CS is achieved for all *** the macroscopic behaviours and the microscopic behaviours are examined and compared considering different loading modes,confining stresses and intermediate stress ratios(b).The critical state lines(CSLs)are found to be unique and independent of the loading modes,but dependent on the b *** CSLs with b=0 and b=1 form the two boundaries of CSLs respectively beyond which CSLs under all other b tests cannot go *** different strength criteria are examined and compared in terms of both peak and CS *** Mohr-Coulomb strength criterion is found to be only suitable for axisymmetric loading *** Lade-Duncan criterion is only suitable for describing peak strengths,which is dependent on the loading modes and confining *** Satake criterion and Matsuoka-Nakai criterion are the more appropriate strength criteria for describing CS failures,indicating that the CS values of both the Satake parameter and the Matsuoka-Nakai parameter describe an inherent property that characterizes the CS failure for a given type of *** CS mechanical coordination number is fitted by a curved line for a given b value,which is unique regardless of the loading *** peak and CS values of both major and minor principal fabric tensors decrease with increasing b values,while they increase with increasing b values for the intermediate principal fabric tensor.

关键词： Discrete element method Intermediate stress ratio Dilation Critical state Failure criterion