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Thermal effects on prediction accuracy of dense granite mechanical behaviors using modified maximum tangential stress criterion

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1734-1748页

作者： Gan Feng Chun Zhu Xiaochuan Wang Shibin Tang College of Water Resource and Hydropower Sichuan UniversityChengdu610065China Key Laboratory of Deep Earth Science and Engineering(Sichuan University) Ministry of EducationChengdu610065China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian116024China

Thermally-induced changes in the fracture properties of geological reservoir rocks can influence their stability,transport characteristics,and performance related to various deep subsurface energy projects.The modified maximum tangential stress(MMTS)criterion is a classical theory for predicting the fracture instability of rocks.However,there is a lack of research on the accuracy of MMTS theory when rocks are subjected to different temperatures.In this study,mechanical theoretical analysis and failure and fracture mechanics experiments of granite under the influence of temperatures ranging from 20℃to 600℃are carried out.The results showed that the theoretical estimated value of MMTS differs significantly from the experimental data at 20℃-600℃.The Keff/KIC ratio is less than the experimental test value due to the critical crack growth radius(rc)estimated by the conventional method being larger than the critical crack growth radius(rce)derived from the experimental data.Varied temperatures affect the fracture process zone size of fine-grained,compact granite,and the MMTS theoretical estimation results.Therefore,it is essential to modify the critical crack growth radius for MMTS theory to accurately predict the fracture characteristics of thermally damaged rocks.In addition,the variation of the rock’s me-chanical properties with temperature and its causes are obtained.Between 20℃and 600℃,the mode-Ⅰ,mode-Ⅱ,and mixed-mode(a-30℃and 45℃)fracture toughness and Brazilian splitting strength of the granite decrease by 80%and 73%,respectively.When the rock is heated above 400℃,its deterioration is mainly caused by a widening of its original cracks.

关键词： Underground geotechnical engineering Hot dry rock(HDR) Geothermal temperature Fracture behavior

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A review on the forward osmosis applications and fouling control strategies for wastewater treatment

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Frontiers of Chemical Science and Engineering 2022年第5期16卷 661-680页

作者： Linwei zhu chun Ding Tengyang zhu Yan Wang Key Laboratory of Material Chemistry for Energy Conversion and Storage(Huazhong University of Science and Technology) Ministry of EducationWuhan 430074China Hubei Key Laboratory of Material Chemistry and Service Failure School of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China

During the last decades,the utilization of osmotic pressure-driven forward osmosis technology for wastewater treatment has drawn great interest,due to its high separation efficiency,low membrane fouling propensity,high water recovery and relatively low energy consumption.This review paper summarizes the implementation of forward osmosis technology for various wastewater treatment including municipal sewage,landfill leachate,oil/gas exploitation wastewater,textile wastewater,mine wastewater,and radioactive wastewater.However,membrane fouling is still a critical issue,which affects water flux stability,membrane life and operating cost.Different membrane fouling types and corresponding fouling mechanisms,including organic fouling,inorganic fouling,biofouling and combined fouling are therefore further discussed.The fouling control strategies including feed pre-treatment,operation condition optimization,membrane selection and modification,membrane cleaning and tailoring the chemistry of draw solution are also reviewed comprehensively.At the end of paper,some recommendations are proposed.

关键词： forward osmosis wastewater treatment membrane fouling fouling control

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Experimental study on the shear performance of quasi-NPR steel bolted rock joints

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第2期15卷 350-362页

作者： Manchao He Shulin Ren Haotian Xu Senlin Luo Zhigang Tao Chun Zhu State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing100083China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China

Quasi-NPR(negative Poisson’s ratio)steel is a new type of super bolt material with high strength,high ductility,and a micro-negative Poisson’s effect.This material overcomes the contrasting characteristics of the high strength and high ductility of steel and it has significant energy-absorbing characteristics,which is of high value in deep rock and soil support engineering.However,research on the shear resistance of quasi-NPR steel has not been carried out.To study the shear performance of quasi-NPR steel bolted rock joints,indoor shear tests of bolted rock joints under different normal stress conditions were carried out.Q235 steel and#45 steel,two representative ordinary bolt steels,were set up as a control group for comparative tests to compare and analyze the shear strength,deformation and instability mode,shear energy absorption characteristics,and bolting contribution of different types of bolts.The results show that the jointed rock masses without bolt reinforcement undergo brittle failure under shear load,while the bolted jointed rock masses show obvious ductile failure characteristics.The shear deformation ca-pacity of quasi-NPR steel is more than 3.5 times that of Q235 steel and#45 steel.No fracture occurs in the quasi-NPR steel during large shear deformation and it can provide stable shear resistance.However,the other two types of control bolts become fractured under the same conditions.Quasi-NPR steel has significant energy-absorbing characteristics under shear load and has obvious advantages in terms of absorbing the energy released by shear deformation of jointed rock masses as compared with ordinary steel.In particular,the shear force plays a major role in resisting the shear deformation of Q235 steel and#45 steel,therefore,fracture failure occurs under small bolt deformation.However,the axial force of quasi-NPR steel can be fully exerted when resisting joint shear deformation;the steel itself does not break when large shear deformation occurs,and the supporting effect of the jointed rock mass is ef

关键词： Energy absorption bolt Quasi-NPR(Negative Poisson’s ratio)steel Bolted rock joints Shear test Shear performance

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Toward an in-depth evaluation of the ecosystem component of CMIP6 Earth system models

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Advances in Climate Change Research 2021年第4期12卷 581-583页

作者： zhu Zai-chun School of Urban Planning and Design Peking University Shenzhen Graduate SchoolPeking UniversityShenzhen518055China

Reliable future climate projection is essential to provide the scientific basis for climate mitigation and adaptation policies.The Earth system model(ESM)is an important tool for future climate projection,as it provides future climate projections under various scenarios and inferences of potential solutions to climate mitigation and adaptation.However,projecting future climate using ESMs has proven challenging because these models consist of highly complex coupled components that simulate the Earth system's physical,chemical,and biological processes.Compared to previous Coupled Model Intercom-parison Project(CMIP)phases,the sixth phase of the CMIP(CMIP6)now includes more improved ESMs.The improve-ments in the spatial resolution,parameterization,and repre-sentation of processes of these latest-generation ESMs provide opportunities to advance our understanding of the Earth sys-tem but are also likely to increase the spread of the simulations across ESMs(Pascoe et al.,2019).Comparison of model simulations against observations is essential for improving confidence in their utility for climate projections and attribu-tion studies and for identifying deficiencies in models such that the parameterization and representation of processes can be further improved.

关键词： Earth CMIP system

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Fracture of two three-dimensional parallel internal cracks in brittle solid under ultrasonic fracturing

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 757-769页

作者： Haijun Wang Hanzhang Li Lei Tang Xuhua Ren Qingxiang Meng Chun Zhu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing210029China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China

Similar to hydraulic fracturing(HF), the coalescence and fracture of cracks are induced within a rock under the action of an ultrasonic field, known as ultrasonic fracturing(UF). Investigating UF is important in both hard rock drilling and oil and gas recovery. A three-dimensional internal laser-engraved crack(3D-ILC) method was introduced to prefabricate two parallel internal cracks within the samples without any damage to the surface. The samples were subjected to UF. The mechanism of UF was elucidated by analyzing the characteristics of fracture surfaces. The crack propagation path under different ultrasonic parameters was obtained by numerical simulation based on the Paris fatigue model and compared to the experimental results of UF. The results show that the 3D-ILC method is a powerful tool for UF research.Under the action of an ultrasonic field, the fracture surface shows the characteristics of beach marks and contains powder locally, indicating that the UF mechanism includes high-cycle fatigue fracture, shear and friction, and temperature load. The two internal cracks become close under UF. The numerical result obtained by the Paris fatigue model also shows the attraction of the two cracks, consistent with the test results. The 3D-ILC method provides a new tool for the experimental study of UF. Compared to the conventional numerical methods based on the analysis of stress-strain and plastic zone, numerical simulation can be a good alternative method to obtain the crack path under UF.

关键词： Three-dimensional internal laser-engraved crack(3D-ILC) Interaction of cracks Ultrasonic fatigue Penny-shaped crack Fracture mechanics High-cycle fatigue

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Investigation of a non-explosive directional roof cutting technology for self-formed roadway

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International Journal of Mining Science and Technology 2022年第5期32卷 997-1008页

作者： Quan Zhang Manchao He Jiong Wang Shan Guo Chun Zhu Zhigang Tao Chao Wang School of Mines China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Geomechanics&Deep Underground Engineering China University of Mining and Technology-BeijingBeijing 100083China School of Earth Sciences and Engineering Hohai UniversityNanjing 210098China

Traditional explosives have characteristics of high risk,large vibration,and poor directional fracturing.Consequently,an instantaneous expander with a single crack surface(IESCS),which is a novel nonexplosive directional rock-breaking technique,has been developed.The directional roof-cutting mechanism of the IESCS method,driven by high-pressure gas,was theoretically analyzed.Laboratory experiments and numerical simulations proved the directional slitting effect of the IESCS method to be excellent.Compared with shaped-charge blasting,the charge of IESCS was reduced by 8.9%,but the crack rate increased by 9%in field tests.After IESCS pre-splitting,the roof directionally collapsed along the cutting line,and the gangue filled the goaf.Moreover,the directional roof cutting by the IESCS could decrease roadway stress.The average pressure of hydraulic supports on the cutting side of the roof was 31%lower than that on the non-cutting side of the roof after pre-splitting.After the self-formed roadway constructed by the IESCS was stabilized,the final relative displacement of the roof and floor was 157.3 mm,meeting the required standard of the next working face.Thus,the IESCS was effectively applied to directional roof pre-splitting.The results demonstrate the promising potential of IESCS in the mining and geotechnical fields.

关键词： Instantaneous expander with a single crack surface Non-explosive Directional roof cutting Self-formed roadways Pillarless mining

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Ultrastable nickel single-atom catalysts with high activity and selectivity for electrocatalytic CO_(2)methanation

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Nano Research 2023年第7期16卷 8987-8995页

作者： Ling-Chan Tian Jin-Nian Hu Yang Meng Jin-Xia Liang Chun Zhu Jun Li School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry Southern University of Science and TechnologyShenzhen 518055China Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education Tsinghua UniversityBeijing 100084China

Electrochemical conversion of CO_(2)into valuable hydrocarbon fuel is one of the key steps in solving carbon emission and energy issue.Herein,we report a non-noble metal catalyst,nickel single-atom catalyst(SAC)of Ni_(1)/UiO-66-NH_(2),with high stability and selectivity for electrochemical reduction of CO_(2)to CH_(4).Based on ab initio molecular dynamics(AIMD)simulations,the CO_(2)molecule is at first reduced into CO_(2)-when stably adsorbed on a Ni single atom with the bidentate coordination mode.To evaluate its activity and selectivity for electrocatalytic reduction of CO_(2)to different products(HCOOH,CO,CH3OH,and CH_(4))on Ni_(1)/UiO-66-NH_(2),we have used density functional theory(DFT)to study different reaction pathways.The results show that CH_(4) is generated preferentially on Ni_(1)/UiO-66-NH_(2)and the calculated limiting potential is as low as-0.24 V.Moreover,the competitive hydrogen evolution reaction is unfavorable at the activation site of Ni_(1)/UiO-66-NH_(2)owing to the higher limiting potential of-0.56 V.Furthermore,the change of Ni single atom valence state plays an important role in promoting CO_(2)reduction to CH_(4).This work provides a theoretical foundation for further experimental studies and practical applications of metal-organic framework(UiO-66)-based SAC electrocatalysts with high activity and selectivity for the CO_(2)reduction reaction.

关键词： single atom catalyst density functional theory CO_(2)reduction metal-organic framework electrocatalysis

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Model test of negative Poisson’s ratio cable for supporting super-largespan tunnel using excavation compensation method

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1355-1369页

作者： Manchao He Aipeng Guo Zhifeng Du Songyuan Liu Chun Zhu Shiding Cao Zhigang Tao State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing100083China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China Department of Civil and Mineral Engineering University of TorontoTorontoM5S 1A4Canada School of Earth Sciences and Engineering Hohai UniversityNanjing210098China Shenzhen General Integrated Transportation and Municipal Engineering Design and Research Institute Co.Ltd. Shenzhen518003China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

In recent years,there is a scenario in urban tunnel constructions to build super-large-span tunnels for traffic diversion and route optimization purposes.However,the increased size makes tunnel support more difficult.Unfortunately,there are few studies on the failure and support mechanism of the surrounding rocks in the excavation of supported tunnel,while most model tests of super-large-span tunnels focus on the failure characteristics of surrounding rocks in tunnel excavation without supports.Based on excavation compensation method(ECM),model tests of a super-large-span tunnel excavation by different anchor cable support methods in the initial support stage were carried out.The results indicate that during excavation of super-large-span tunnel,the stress and displacement of the shallow surrounding rocks decrease,following a step-shape pattern,and the tunnel failure is mainly concentrated on the vault and spandrel areas.Compared with conventional anchor cable supports,the NPR(negative Poisson’s ratio)anchor cable support is more suitable for the initial support stage of the super-large-span tunnels.The tunnel support theory,model test materials,methods,and the results obtained in this study could provide references for study of similar super-large-span tunnels。

关键词： Super-large-span tunnel Excavation compensation method(ECM) NPR(Negative Poisson’s ratio)anchor cable Model test

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Analysis of sliding electric contact characteristics in augmented railgun based on the combination of contact resistance and sliding friction coefficient

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Defence Technology（防务技术） 2020年第4期16卷 747-752页

作者： chun-yan zhu Bao-ming Li National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyChina

The contact resistance between the armature and rails is an important indicator of the contact characteristics in electromagnetic launches.As the contact resistance depends not only on the contact state but also on the contact stress and temperature,there are some limitations in analyzing the contact characteristics using only the contact resistance.In this paper,the contact characteristics of the augmented railgun are analyzed by the combination of contact resistance and sliding friction coefficient.Firstly,the theoretical calculation model of the contact resistance and friction coefficient of the augmented electromagnetic railgun is established.Then the contact resistance and friction coefficient are calculated by the measured values of the muzzle voltage,rail current and armature displacement.Finally,the contact characteristics are analyzed according to the features of the waveforms of the contact resistance and the friction coefficient,and the analysis conclusions are verified by experimental rail images.The results showed that:the aluminum melt film gradually formed on the contact surface reduces the contact resistance and the friction coefficient;the wear and erosion of the armature cause deterioration of the contact state;after the transition,the reliability of the sliding contact between the armature and rails decreases,resulting in an increase in contact resistance.

关键词： Augmented railgun Contact resistance Friction coefficient Contact characteristics

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A hybrid artificial bee colony algorithm and support vector machine for predicting blast-induced ground vibration

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 861-876页

作者： zhu chun Xu Yingze Wu Yongxin He Manchao zhu Chuanqi Meng Qingxiang Lin Yun School of Earth Sciences and Engineering Hohai UniversityNanjing 210098China State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining andTechnology(Beijing)Beijing 100083China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines AnhuiUniversity of Science and TechnologyHuainan 232001China College of Petroleum Engineering Xi’an Shiyou UniversityXi’an 710065China School of Resources and Safety Engineering Central South UniversityChangsha 410083China

Because nearby construction has harmful effects,precisely predicting blast-induced ground vibration is critical.In this paper,a hybrid artificial bee colony(ABC)and support vector machine(SVM)model was proposed for predicting the value of peak particle velocity(PPV),which is used to describe blast-induced ground vibration.To construct the model,5 potentially relevant factors,including controllable and uncontrollable parameters,were considered as input parameters,and PPV was set as the output parameter.Forty-five samples were recorded from the Hongling lead-zinc mine.An ABC-SVM model was developed and trained on 35 samples via 5-fold cross-validation(CV).A testing set(10 samples)was used to evaluate the prediction performance of the ABC-SVM model.SVM and four empirical models(United States Bureau of Mines(USBM),Amraseys-Hendron(A-H),Langefors-Kihstrom(L-K),and Central Mining Research Institute(CMRI))also were introduced for comparison.Next,the performances of the models were analyzed by using 3 statistical parameters:the correlation coefficient(R2),root-mean-square error(RMSE),and variance accounted for(VAF).ABC-SVM had the highest R2 and VAF values followed by the SVM,A-H,USBM,CMRI,and L-K methods.The results demonstrated that ABC-SVM outperformed SVM and the empirical predictors for predicting PPV.Moreover,the best results from the R2,RMSE,and VAF indices were 0.9628,0.2737,and 96.05%for the ABC-SVM model.The sensitivities of the parameters also were investigated,and the height difference between the blast point and the monitoring station was found to be the parameter that had the most influence on PPV.

关键词： recycled concrete frame-shear wall concealed bracings shaking table test nonlinear time-history response analysis

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