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Micro-and macro-fractures of coarse granite under true-triaxial unloading conditions

mining Science and Technology 2011年第3期21卷 389-394页

作者： He Manchao Nie Wen Zhao Zhiye Cheng Cheng school of Mechanics and civil engineering China university of mining ＆ Technology Beijing 100083 China State Key Laboratory of Geomechanics and Deep Underground engineering Beijing 100083. China school of civil and environmental engineering Nanyang Technological University Singapore

We studied the mechanical behavior of rock under different boundary conditions, based on the fractal characteristics of fractures in terms of microscopic and macroscopic investigations. Three rectangular granite specimens of similar dimensions were tested by a triaxial rock testing machine under uniaxial compression （UC）, confined compression （CC） and true-triaxial unloading conditions （RB） under rock burst boundary conditions. The failure processes of these specimens were investigated via examinations of their fracture behavior on a macro-scale by laser profilometers and on a micro-scale by a scanning electron microscopic （SEM） imaging technique. The SEM images, showing the spailing features of RB frag- ments, are compared with the grain dislocations under UC and CC conditions. Based on a variogram method, two fractal parameters, i.e., fractal dimensions （Dr^d） and the scale dependent fractal parameter Kv, were induced to present the surface roughness of scanning profiles in all directions. The fitted ellipses of Dr^d distribution show that RB surface has the smallest eccentricity, followed by the CC surface, while the UC surface had the largest eccentricity. As a result of this assessment, we conclude that rocks are affected by shear traction in an intermediate stress direction, which will cause fractures generated during rock bursts to twist rather than to tilt as shown in the uniaxial compression and the confined compres- sion tests.

关键词： Rock burstsSurface roughness Stress distribution Fractal dimension Coarse granite

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3-D discontinuum numerical modeling of subsidence incorporating ore extraction and backfilling operations in an underground iron mine in China

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International Journal of mining Science and Technology 2017年第2期27卷 191-201页

作者： Huang Gang Kulatilake Pinnaduwa H.S.W. Shreedharan Srisharan Cai Sijing Song Hongqing school of Resources and environmental engineering Wuhan University of Technology school of civil and environmental engineering University of Science and TechnologyBeijing Rock Mass Modeling and Computational Rock Mechanics Laboratories University of Arizona

An underground iron mine in China has been used as a case-study to research the subsidence due to ore extraction and backfilling during open stoping operations. A 3-D discontinuum numerical model was built incorporating geologic complexities including faults and interfaces between different lithologies,and the stoping and backfilling sequence adopted from the mine plans. The stoping was carried out in two vertically stacked horizontal layers, with a total of 16 stopes. Large displacements of up to 50 cm were observed along the roof of the stopes, and a maximum surface subsidence of 22.5 cm was *** was found to eliminate subsequent displacements and subsidence. The extraction of the upper orebody was found to influence displacements in the lower orebody. Finally, a subsidence profile was constructed to show the subsidence at all locations along the length of the surface and region of influence on the surface.

关键词： Underground iron mine Discontinuum numerical modeling Open stoping Backfill Subsidence

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In situ kinetics and flocs conformation studies of kaolinite flocculated by Chi-g-CPAM

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International Journal of Minerals,Metallurgy and Materials 2023年第5期30卷 813-823页

作者： Ruijing Xu Wenjie Zou Bo Rao Wei Zhao Ting Wang Zhijun Zhang State Key Laboratory of High-Efficient mining and Safety of Metal Mines of Ministry of Education University of Science and Technology BeijingBeijing 100083China school of civil and Resources engineering University of Science and Technology BeijingBeijing 100083China school of Chemical and environmental engineering China University of Mining and TechnologyBeijing 100083China

This study presents a comparative study of the flocculation behavior of kaolinite induced by chitosan-graft-poly(acrylamide-dimethyl diallyl ammonium chloride)(Chi-g-CPAM) and a commercial cationic polyacrylamide(CPAM).The flocculation behaviour was characterised in terms of both flocculation kinetics and the corresponding morphology changes during *** Chi-g-CPAM and CPAM were grafted from silica wafers by means of atom transfer radical polymerization(ATRP).The quartz crystal microbalance with dissipation(QCM-D) tests were *** equilibrium time flocculated by Chi-g-CPAM was found to be 0.46 times as that of CPAM,together with a larger total mass of kaolinite *** flocculation behaviour by Chi-g-CPAM can be well captured by a pseudo-first-order *** contrast,the presence of CPAM leads to a more complex kinetics.A relatively larger fitting slope(0.4663) was obtained at the initial stage but the fitting slope droped to 0.2026 after 800 min,indicating a densification process caused by *** flocculation kinetics of CPAM can be captured by the Elovich model for the inital stage but the combination of pseudo-first-order and pseudo-second-order models for the latter stages,which can be attributed to the long chain of *** a dosage of 75 g/t,the settling test with Chi-g-CPAM exhibits the same turbidity in the supernatant but a smaller layer thickness of the settlement compared to *** study enables a better understanding of the flocculation behavior and contributes to the development of efficient flocculants in mineral processing and tailings treatment.

关键词： Chi-g-CPAM flocculation QCM-D kinetics conformation

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Shoreline Change Modeling on Emergency Beach Nourishment Project on West Beach of Beidaihe,China

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China Ocean engineering 2010年第2期24卷 277-289页

作者：匡翠萍潘毅张宇刘曙光杨燕雄张甲波 Department of Hydraulic engineering College of Civil EngineeringTongji University Department of civil & environmental engineering Jackson State UniversityJackson school of Resources and Safety engineering China University of Mining and Technology(Beijing) Qinhuangdao Mineral Resource and Hydrogeological Brigade Hebei Geological Prospecting Bureau

By use of a shorehne-change numerical model （GENESIS） based on one-line theory, a preliminary modeling study on shoreline changes caused by a beach nourishment project in Beidaihe, China, is presented in this paper. Firstly, the GENESIS model is verified and model sensitivity to the major parameter changes is discussed by simulating a hydraulic model test. The beach nourishment project, after that the shoreline change is kept being monitored, is a small-scale emergency one carried out to use two bathing places on the west beach in the summer, 2008. In this paper the shoreline changes caused by the beach nourishment project are modeled by the GENESIS model, and the computed results fit well with the measured shorelines. With the same model and parameters, a long-term performance of the project is predicted, and the result shows that the bathing places only can be suitable for bathing in 2 to 3 years without subsequence nourishment project. Therefore, it is proposed to nourish the beaches in time to keep the service life of the beach in recent years and carry out the beach nourishment project for the whole west beach as soon as possible.

关键词： GENESIS model shoreline change beach nourishment west beach in Beidaihe

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Numerical Simulation Study of a Novel Horizontally Layered Enhanced Geothermal System:A Case Study of the Qiabuqia Geothermal Area,Qinghai Province,China

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Journal of Thermal Science 2021年第4期30卷 1328-1340页

作者： GAO Kun LIU Weiqun MA Tianran HU Yang FANG Tian YE Lei school of Mechanics and civil engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhou 221116China

Hot dry rock,as a renewable and sustainable energy source,can alleviate resource shortages and environmental *** on data from the Qiabuqia geothermal field and an established thermal-hydrological-mechanical coupled mathematical model,a novel horizontally layered enhanced geothermal system(EGS)is proposed and compared with the conventional double vertical well *** the simulated conditions in this paper,the comprehensive heat recovery performance of the horizontally layered EGS is significantly better than that of the double vertical well ***,although the average production temperature of the double vertical well EGS is higher than that of the horizontally layered EGS in the attenuation stage,the heat power output of the horizontally layered EGS ranges from 6.10 MW to 12.25 MW,which is 1.36 to 1.67 times that of the double vertical well ***,the heat recovery rate of the horizontally layered EGS is 6.63%higher than that of the double vertical well EGS and is thus more ***,parametric analysis was performed to investigate the influence of the controllable parameters on heat recovery for the horizontally layered *** heat power output and heat extraction ratio are proportional to the pressure difference and well spacing and inversely proportional to the injection fluid *** thermal power output is most greatly influenced by the pressure difference,followed by the well spacing and injection fluid *** effects of the pressure difference and well spacing on the heat recovery rate are almost the same,and the injection fluid temperature has no effect.

关键词： hot dry rock enhanced geothermal system thermal-hydrological-mechanical coupling numerical simulation parameter analysis

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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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Uniqueness of rate-dependency, creep and stress relaxation behaviors for soft clays

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Journal of Central South university 2015年第1期22卷 296-302页

作者：朱启银尹振宇徐长节殷建华夏小和 Department of civil engineering Shanghai Jiao Tong University State Key Laboratory for Geomechanics and Deep Underground engineering(China university of mining and Technology) Lunan university Ecole Centrale de NantesUMR CNRS Ge M Nantes France school of civil engineering and Architecture Departments East China Jiaotong University Department of civil and environmental engineering Hong Kong Polytechnic University

This work focuses on the uniqueness of rate-dependency, creep and stress relaxation behaviors for soft clays under one-dimensional condition. An elasto-viscoplastic model is briefly introduced based on the rate-dependency of preconsolidation pressure. By comparing the rate-dependency formulation with the creep based formulation, the relationship between rate-dependency and creep behaviors is firstly described. The rate-dependency based formulation is then extended to derive an analytical solution for the stress relaxation behavior with defining a stress relaxation coefficient. Based on this, the relationship between the rate-dependency coefficient and the stress relaxation coefficient is derived. Therefore, the uniqueness between behaviors of rate-dependency, creep and stress relaxation with their key parameters is obtained. The uniqueness is finally validated by comparing the simulated rate-dependency of preconsolidation pressure, the estimated values of secondary compression coefficient and simulations of stress relaxation tests with test results on both reconstituted Illite and Berthierville clay.

关键词： soft clays creep rate-dependency stress relaxation oedometer test

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Effect of Na2CO3 and CaCO3 on Coreduction Roasting of Blast Furnace Dust and High-phosphorus Oolitic Hematite

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Journal of Wuhan university of Technology(Materials Science) 2017年第3期32卷 517-524页

作者：曹允业孙体昌 KOU Jue XU Chengyan GAO Enxia school of civil & environmental engineering Key Laboratory of High-Efficient Mining and Safety of Metal Mines Ministry of Education University of Science and Technology Beijing Beijing 100083 China

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.

关键词： Na2CO3 CaCO3 blast furnace dust high-phosphorus oolitic hematite coreduction roasting

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Theoretical Study of Similar Experimental Method for Durability of Concrete under Artifi cial Climate Environment

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Journal of Wuhan university of Technology(Materials Science) 2016年第2期31卷 345-354页

作者：耿欧 FENG Tai LI Debao LI Qingtao school of Mechanics and civil engineering China University of Mining and Technology Xuzhou 221116 China Jiangsu Key Laboratory of environmental lmpact and Structural Safety in engineering China University of Mining and Technology Xuzhou 221116China State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and Technology Xuzhou 221116 China

Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete（SEMDC）was *** existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were *** factors affecting the durability of concrete were found through literature *** factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these *** various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were *** to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the *** were few other parameters which need to be changed in SEMDC,making the test easy to be *** to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the ***,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.

关键词： concrete similarity theory artifi cial climate similar experiment accelerate durability

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An Innovative Non-Pillar Coal-mining Technology with Automatically Formed Entry: A Case Study

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engineering 2020年第11期6卷 1315-1329页

作者： Xingyu Zhang Manchao He Jun Yang Eryu Wang Jiabin Zhang Yue Sun State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyBeijing 100083.China school of Mechanics and civil engineering China University of Mining and TechnologyBeijing 100083China Department of civil Environmental and Architectural EngineeringUniversity of ColoradoBoulderCO 80309USA Institute of mining Research Inner Mongolia University of Science and TechnologyBaotou 014010China

A non-pillar coal-mining technology with an automatically formed entry is proposed,which reduces the waste of coal resources and the underground entry drivage *** key techniques in this technology cooperate to achieve automatic formation and retaining of the gob-side entry,and to realize nonpillar ***-resistance large deformation(CRLD)support ensures the stability of the entry roof;directional presplitting blasting(DPB)separates the entry roof and the gob roof;and a blockinggangue support system(BGSS)integrates the caved rock material as an effective entry *** industrial test was conducted to verify the engineering effects of these key *** field application results showed that the retained entry was under the pressure-relief zone due to the broken-expansion nature of the caved rock mass within the DPB *** going through a provisional dynamic pressure-bearing zone,the retained entry entered the stability *** final stable entry meets the requirements of safety and *** research results demonstrate the good engineering applicability of this *** taking the framework of the technology design principles into consideration and adjusting the measures according to different site conditions,it is expected that the proposed non-pillar coal-mining technology can be popularized on a large scale.

关键词： Non-pillar mining Entry support Retained entry Rock engineering Industrial test

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