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Analysis of the interaction between bolt-reinforced rock and surface support in tunnels based on convergence-confinement method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 1936-1951页

作者： zhenyu sun Dingli Zhang Qian Fang Yanjuan Hou Nanqi Huangfu Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing100044China

To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockbolts and the surface support.The rock mass is assumed to be elastic-brittle-plastic material,obeying the linear Mohr-Coulomb criterion or the non-linear Hoek-Brown criterion.According to the strain states of the tunnel wall at bolt and surface support installation and the relative magnitude between the bolt length and the plastic depth during the whole process,six cases are categorized upon solving the problem.Each case is divided into three stages due to the different effects of the active rockbolts and the passive surface support.The fictitious pressure is introduced to quantify the threedimensional(3D)effect of the tunnel face,and thus,the actual physical location along the tunnel axis of the analytical section can be considered.By using the bolt-rock strain compatibility and the rocksurface support displacement compatibility conditions,the solutions of longitudinal tunnel displacement and the reaction pressure of surface support along the tunnel axis are obtained.The proposed analytical solutions are validated by a series of 3D numerical simulations.Extensive parametric studies are conducted to examine the effect of the typical parameters of rockbolts and surface support on the tunnel displacement and the reaction pressure of the surface support under different rock conditions.The results show that the rockbolts are more effective in controlling the tunnel displacement than the surface support,which should be installed as soon as possible with a suitable length.For tunnels excavated in weak rocks or with restricted displacement control requirements,the surface support should also be installed or closed timely with a certain stiffness.The proposed method provides a convenient alternative approach for the optimization of rockbolts and surface support at the preliminary stage of tunnel design.

关键词： Analytical model Longitudinal tunnel displacement Fictitious pressure Active rockbolts Surface support reaction pressure Tunnel design

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Electrocatalytic Reduction of CO_(2)to CO with Almost 100%Faradaic Efficiency Using Oxygen-Vacancy Enriched Two-Dimensional MgO

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CCS Chemistry 2024年第6期6卷 1477-1486页

作者： Yu Han sunggi An Xinyu Zhan Leiduan Hao Liang Xu Song Hong Dongmin Park Yuxin Chen Yiwen Xu Jiwen Zhao Xinyi Tan Alex W.Robertson Yousung Jung zhenyu sun State Key Laboratory of Organic-Inorganic Composites College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029 Department of Chemical and Biomolecular Engineering(BK21four) Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141 Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081 Department of Physics University of WarwickCoventry

The design and development of cheap,abundant,and efficient electrocatalysts for selective CO_(2)electroreduction is highly desirable yet remains an ongoing challenge.Herein,we report on our discovery of the use of two-dimensional MgO rich in oxygen vacancies(VO)as an electrocatalyst for the efficient reduction of CO_(2)to yield CO in 1-butyl-3-methylimidazolium hexafluorophosphate dissolved in acetonitrile.The faradaic efficiency toward CO reaches as high as 99.6±0.24%with a current density of up to 40.8 mA cm−2.Density functional theory calculations illustrate that the introduction of VO in MgO substantially lowers the reaction-free energy for the transformation of*COO−to*COOH,the potential determining step,which greatly boosts CO_(2)conversion efficiency.This work opens the way to realizing economic and efficient CO_(2)electrolysis of group II metals.

关键词： CO_(2)reduction electrocatalysis CO MgO ionic liquid oxygen-vacancy

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Development of in situ characterization techniques in molecular beam epitaxy

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Journal of Semiconductors 2024年第3期45卷 9-32页

作者： Chao Shen Wenkang Zhan Manyang Li zhenyu sun Jian Tang Zhaofeng Wu Chi Xu Bo Xu Chao Zhao Zhanguo Wang Laboratory of Solid State Optoelectronics Information Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 101804China School of Physics Science and Technology Xinjiang UniversityUrumqi 830046China School of New Energy and Electronics Yancheng Teachers UniversityYancheng 224002China Key Laboratory of Optoelectronic Materials and Devices Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

关键词： epitaxial growth thin film in situ characterization molecular beam epitaxy(MBE)

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Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

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Frontiers of Structural and Civil Engineering 2023年第5期17卷 745-762页

作者： Xuefei HONG Dingli ZHANG zhenyu sun Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load.The ground layers are assumed to be linear-elastic with full-stick contact between them.To solve the proposed multi-boundary problem,a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries.Based on the principle of linear-elastic superposition,the multi-boundary problem is converted into a superposition of multiple single-boundary problems.The conformal mappings of different boundaries are independent of each other,which allows the stress and displacement fields to be obtained by the sum of components from each boundary.The analytical results are validated based on numerical and in situ monitoring results.The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground;thus,it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings.Moreover,the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词： analytical model mechanical response multi-layered ground shallow tunneling ground surface load complex variable solution

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Cadmium-based metal-organic frameworks for high-performance electrochemical CO_(2) reduction to CO over wide potential range

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Chinese Journal of Chemical Engineering 2022年第3期35卷 143-151页

作者： Xin Li Song Hong Leiduan Hao zhenyu sun State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China College of Materials Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China

Electrochemical CO_(2)reduction(ECR)powered by renewable energy sources provides a sustainable avenue to producing carbon-neutral fuels and chemicals.The design and development of high performance,cost-effective,and stable catalysts for ECR remain a focus of intense research.Here,we report a novel electrocatalyst,two-dimensional cadmium-based 1,4-benzenedicarboxylate metal-organic frameworks(Cd-BDC MOFs)which can effectively convert CO_(2)to CO with a faradaic efficiency(FE)of more than80.0%over the voltage range between-0.9 and-1.1 V(versus reversible hydrogen electrode,vs.RHE)in 0.1 mol·L^(-1) CO_(2)-saturated KHCO_(3)solution with an H-type cell,reaching up to 88.9%at-1.0 V(vs.RHE).The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature.The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type.Especially,high CO FEs exceeding 90.0%can be attained on the Cd-BDC electrode at potentials ranging from-0.16 to-1.06 V(vs.RHE)in 0.5 mol·L^(-1) KHCO_(3)solution by using a gas diffusion electrode cell system.The maximum CO FE approaches~97.6%at-0.26 V(vs.RHE)and the CO partial geometric current density is as high as about 108.1 mA·cm^(-2) at-1.1 V(vs.RHE).This work offers an efficient,low cost,and alternative electrocatalyst for CO_(2)transformation.

关键词： Electrochemical carbon dioxide reduction Carbon monoxide Cadmium Metal-organic framework Electrocatalysis

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Scientific problems and research proposals for Sichuan–Tibet railway tunnel construction

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Underground Space 2022年第3期7卷 419-439页

作者： Dingli Zhang zhenyu sun Qian Fang Sichuan–Tibet Railway Research Institute Beijing Jiaotong UniversityBeijing 100044China Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

The Sichuan–Tibet railway construction has received significant attention from both China and abroad.The new section from Ya’an to Nyingchi is about 1018.6 km long,including 69 tunnels with a total length of 841.7 km.The longest tunnel(Yigong tunnel)is 42.4 km long.The successful construction of the Sichuan–Tibet railway depends largely on tunnel construction.Due to the complex conditions,tunnel construction for the Sichuan–Tibet railway poses great challenges to the research community.This paper aims to illustrate the necessity of interdisciplinary and joint research to solve problems associated with tunnel construction that will be encountered in the immediate future and facilitate the communication and exchange of ideas between disciplines.To this end,based on a systematic analysis of the available data related to Sichuan–Tibet railway tunnels,six major aspects of the geology,environment,and engineering conditions are identified.Next,based on the engineering responses from the Sichuan–Tibet railway tunnels,potential technical problems and risk characteristics are predicted and evaluated.Further,six key scientific issues are identified and discussed based on a coupled multi-layer analysis of essential tunnel engineering issues.Finally,research directions,technical ideas,and research methods that should be carried out for this project are proposed.

关键词： Sichuan–Tibet railway tunnels Key scientific problems Complex stress environment Deformation mechanism of surrounding rock Dynamic response

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Effect of Size Change on Mechanical Properties of Monolayer Arsenene

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 206-212页

作者：郭娟刘贵立孙震宇 School of Architecture and Civil Engineering Shenyang University of TechnologyShenyang 110870China

The Young's modulus, shear modulus and Poisson's ratio of monolayer arsenene with different sizes were calculated by finite element method, so as to explore the influence of dimension and orientation on the mechanical properties of monolayer arsenene. The calculation results show that the small size has a significant effect on the mechanical properties of the monolayer arsenene. The smaller the size, the larger the Young's modulus and Poisson's ratio of the monolayer arsenene. The size change has a great influence on the Young's modulus of the arsenene handrail direction, and the Young's modulus of the zigzag direction is not sensitive to the size change. Similarly, the size change has a significant effect on the shear modulus of arsenene in the handrail direction, while the shear modulus in the zigzag direction has no significant effect on its size change. For the Poisson's ratio, the situation is just the opposite, and the effect of the size change on the Poisson's ratio of the arsenene zigzag direction is greater than that of the handrail direction.

关键词： finite element method arsenene size change mechanical properties

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Long-term mechanical analysis of tunnel structures in rheological rock considering the degradation of primary lining

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Underground Space 2023年第3期10卷 217-232页

作者： Chang Liu Dingli Zhang Sulei Zhang Qian Fang zhenyu sun Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Qingdao University of TechnologyQingdao 266033China

Rock load on lining structures increases over time for tunnels buried in rheological rock,and in addition deterioration of primary lining is common due to its structural characteristics and service environment attack,where these delayed features affect the mechanical response of tunnels.However,accounting for these delayed features in long-term stability assessment of tunnel structures is complex and has not attracted enough attention.In this paper,an analytical approach is proposed for investigating long-term mechanical response of tunnel structures in rheological rock influenced by degradation of primary lining.For this purpose,degradation of primary lining,char-acterized by decreasing concrete stiffness over time,is quantitatively described by an exponential model.The rheological characteristic of surrounding rock is simulated by the Burgers model.The time-varying solutions for rock deformation and support pressure are obtained by considering the coordinated interaction between surrounding rock and linings,and their correctness is verified by comparing them with numerical results.The results revealed that the pressure imposed on linings due to the rheological behavior of surrounding rock increases over time.As the primary lining degrades,the rheological load is transferred from primary lining to secondary lining,leading to increasing pressure on secondary lining;and a faster degradation rate of primary lining leads to greater pressure on secondary lining.Therefore,the primary lining should not be overlooked in long-term safety assessment of operation tunnels because of its role in bearing and transmitting load.Finally,the tunnel’s design and operational maintenance strategy are discussed when the delay effects of surround-ing rock and lining are taken into account.

关键词： Tunnel structure Rheological rock Primary lining degradation Secondary lining Analytical model Mechanical response

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Photocatalytic nitrogen reduction to ammonia:Insights into the role of defect engineering in photocatalysts

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Nano Research 2022年第4期15卷 2773-2809页

作者： Huidong Shen Mengmeng Yang Leiduan Hao Jinrui Wang Jennifer Strunk zhenyu sun State Key Laboratory of Organic-Inorganic Composites College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China Leibniz Institute for Catalysis at the University of Rostock Rostock 18059Germany

Engineering of defects in semiconductors provides an effective protocol for improving photocatalytic N_(2) conversion efficiency.This review focuses on the state-of-the-art progress in defect engineering of photocatalysts for the N_(2) reduction toward ammonia.The basic principles and mechanisms of thermal catalyzed and photon-induced N_(2) reduction are first concisely recapped,including relevant properties of the N_(2) molecule,reaction pathways,and NH3 quantification methods.Subsequently,defect classification,synthesis strategies,and identification techniques are compendiously summarized.Advances of in situ characterization techniques for monitoring defect state during the N_(2) reduction process are also described.Especially,various surface defect strategies and their critical roles in improving the N_(2) photoreduction performance are highlighted,including surface vacancies(i.e.,anionic vacancies and cationic vacancies),heteroatom doping(i.e.,metal element doping and nonmetal element doping),and atomically defined surface sites.Finally,future opportunities and challenges as well as perspectives on further development of defect-engineered photocatalysts for the nitrogen reduction to ammonia are presented.It is expected that this review can provide a profound guidance for more specialized design of defect-engineered catalysts with high activity and stability for nitrogen photochemical fixation.

关键词： photocatalysis nitrogen reduction ammonia synthesis defect engineering

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High-throughput site-specific N-glycoproteomics reveals glyco-signatures for liver disease diagnosis

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National Science Review 2023年第1期10卷 214-225页

作者： zhenyu sun Bin Fu Guoli Wang Lei Zhang Ruofan Xu Ying Zhang Haojie Lu Shanghai Cancer Center and Institutes of Biomedical Sciences Fudan University Department of Chemistry and NHC Key Laboratory of Glycoconjugates Research Fudan University Eleanor Roosevelt College University of California San Diego

The glycoproteome has emerged as a prominent target for screening biomarkers,as altered glycosylation is a hallmark of cancer cells.In this work,we incorporated tandem mass tag labeling into quantitative glycoproteomics by developing a chemical labeling-assisted complementary dissociation method for the multiplexed analysis of intact N-glycopeptides.Benefiting from the complementary nature of two different mass spectrometry dissociation methods for identification and multiplex labeling for quantification of intact N-glycopeptides,we conducted the most comprehensive site-specific and subclass-specific N-glycosylation profiling of human serum immunoglobulin G(IgG) to date.By analysing the serum of 90 human patients with varying severities of liver diseases,as well as healthy controls,we identified that the combination of IgG1-H3N5F1 and IgG4-H4N3 can be used for distinguishing between different stages of liver diseases.Finally,we used targeted parallel reaction monitoring to successfully validate the expression changes of glycosylation in liver diseases in a different sample cohort that included 45 serum samples.

关键词： glycoproteomics high-throughput quantification N-glycopeptides liver disease

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