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Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial and Fourier domains

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Frontiers of Structural and Civil Engineering 2024年第3期18卷 350-364页

作者： Jixing CAO Yao ZHANG Haijie HE Weibing PENG Weigang ZHAO zhiguo yan Hehua ZHU School of Safety Engineering and Emergency Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China College of Civil and Architectural Engineering Taizhou UniversityTaizhou 318000China College of Civil Engineering and Architecture Zhejiang University of TechnologyHangzhou 310014China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

Automatic detection and assessment of surface cracks are beneficial for understanding the mechanical performance of ultra-high performance concrete(UHPC).This study detects crack evolution using a novel dynamic mode decomposition(DMD)method.In this method,the sparse matrix‘determined’from images is used to reconstruct the foreground that contains cracks,and the global threshold method is adopted to extract the crack patterns.The application of the DMD method to the three-point bending test demonstrates the efficiency in inspecting cracks with high accuracy.Accordingly,the geometric features,including the area and its projection in two major directions,are evaluated over time.The relationship between the geometric properties of cracks and load-displacement curves of UHPC is discussed.Due to the irregular shape of cracks in the spatial domain,the cracks are then transformed into the Fourier domain to assess their development.Results indicate that crack patterns in the Fourier domain exhibit a distinct concentration around a central position.Moreover,the power spectral density of cracks exhibits an increasing trend over time.The investigation into crack evolution in both the spatial and Fourier domains contributes significantly to elucidating the mechanical behavior of UHPC.

关键词： dynamic mode decomposition ultra-high performance concrete crack detection geometric features Fourier domain

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Roof collapse mechanism of weak surrounding rock for deep-buried tunnels under high geostress conditions

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Journal of Mountain Science 2024年第7期21卷 2408-2426页

作者： ZHANG Qi GUO Xiaokang yan zhiguo LEI Zhongdai SHEN Yixin School of Civil Engineering Southeast UniversityNanjing 211189China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

High geostress,a typical attribute of tunnels located at significant depths,is crucial in causing stress-induced failure and influencing the stability of the tunnel crown.This study developed an analytical method for the failure mechanism that occurs in deep-buried tunnel roofs,taking into account the influence of geostress.The limit analysis theory was utilized for deriving analytical solutions about the geometry of the collapsing surface and the limit supporting pressure.The collapsing surface obtained by the analytical solution was validated by the findings of the physical model test,which shows a high level of agreement with the actual one.An extensive investigation was done to explore the effects of the lateral pressure coefficients,the tunnel buried depth,the geological conditions of the surrounding rock,the long-short axis ratio,and the size of the tunnel profile.The findings indicate that an increase in the lateral pressure coefficient from 0.5 to 1.5 results in a reduction in the height of the collapsing zone by 2.08 m and the width of the collapsing zone by 1.15 m,while simultaneously increases the limit supporting pressure by 18.9%.The proposed upper bound method accurately determines the limit supporting pressure and the geometry of the collapsing surface,which aligns well with the results acquired through numerical modelling and on-site monitoring in actual engineering applications.The proposed analytical method can serve as a reference for similar crown failure issues of deep-buried tunnels.

关键词： Geostress Deep-buried tunnels Collapse mechanism Pressure arch Limit analysis HoekBrown criterion

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Experimental study on effect of ductile-iron panel stiffness on mechanical properties of segmental joints of shield tunnels

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Underground Space 2022年第6期7卷 1056-1067页

作者： Long Zhou zhiguo yan Yi Shen Linxing Guan College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Shanghai Municipal Engineering Design Institute(Group)Co.Ltd. Shanghai 200092China

In circular shield tunnels bearing high inner pressure or rectangular shaped shield tunnels,as the axial force at the segmental lining decreases,the bolt load at the segmental joint increases.It is essential to adopt high-stiffness segmental joints to improve the bearing capacity and control the deformation at the joint position.When designing high-stiffness segmental joints,the selection of ductileiron joint panel is crucial.In this study,two types of segmental joints with different joint panels were fabricated,and the effects of joint panel stiffness on the mechanical properties of segmental joints were analyzed through full-scale sagging and hogging bending tests.The results showed that the failure mode of high-stiffness segmental joint was similar to that of large eccentric compression section.According to the difference of panel stiffness,the failure modes can be specified into two types.If the stiffness is sufficient,the joint failure occurs due to the yielding of bolts;otherwise,it occurs due to the large deformation of ductile-iron joint panels.As for the design requirement of segmental joint,the stiffness of joint panel should be sufficient,i.e.,the opening and failure of the joints are finally induced by the bolt deformation.Otherwise,before the plastic deformation of the bolts,the large deformation of the joint panels will occur under a bendingmoment-dominant load,and the bearing capacity of the joints will greatly decrease.

关键词： Ductile-iron joint panel High-stiffness segmental joint Shield tunnel Experimental study

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Full-scale experiment for segmental linings of deep-buried shield tunnels bearing high inner water pressure:Comparison of mechanical behaviors of continuous-and stagger-jointed structures

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Underground Space 2023年第1期8卷 252-266页

作者： Long Zhou Yi Shen Linxing Guan zhiguo yan Wei Sun Yaoliang Li College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Shanghai Municipal Engineering Design Institute(Group)Co.Ltd. Shanghai 200092China Shanghai Foundation Engineering Group Co.Ltd. Shanghai 200002China

Full-scale loading tests were performed on shield segmental linings bearing a high earth pressure and high inner water pressure,focus-ing on the effects of the inner water load and assembly manner on the mechanical properties of the segmental linings.The test results indicate that the deep-buried segmental linings without inner pressure have a high safety reserve.After the action of high inner water pressure,the lining deformation will increase with the reduction of the safety reserve,caused by the significant decrease in the axial force in the linings.Because the bending moment at the segmental joints is transferred to the segment sections in the adjacent ling rings,the convergence deformation,openings of segmental joints,and bolt strains are smaller for the stagger-jointed lining than those for the continuous-jointed lining;however,dislocations appear in the circumferential joints owing to the stagger-jointed assembly.Although it significantly improves the mechanical performance of the segmental lining,stagger-jointed assembly results in compromising the water-proofing safety of circumferential joints.The stagger-jointed assembly manner can be considered to improve the service performance of shield tunnels bearing high inner water pressure on the premise that circumferential joint waterproofing is satisfied.

关键词： Shield tunnel Inner water pressure Continuous-jointed lining Stagger-jointed lining Full-scale experiment

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Infinite horizon H-two/H-infinity control for descriptor systems:Nash game approach

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控制理论与应用（英文版） 2012年第2期10卷 159-165页

作者： zhiguo yan Guoshan Zhang Jiankui Wang School of Electrical Engineering and Automation Tianjin UniversityTianjin 300072China School of Electrical Engineering and Automation Shandong Polytechnic UniversityJinan Shandong 250353China

This paper studies the infinite time horizon mixed H-two/H-infinity control problem for descriptor systems using Nash game approach. A necessary/sufficient condition for the existence of infinite horizon H-two/H-infinity control is presented in the form of two coupled algebraic Riccati equations, respectively. Finally, a suboptimal H-two/H-infinity controller design is given based on an iterative linear matrix inequality algorithm.

关键词： Nash game approach Descriptor system H-two/H-infinity control Coupled algebraic Riccati equations Itetative linear matrix inequality algorithm

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All-silica zeolites screening for capture of toxic gases from molecular simulation

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Chinese Journal of Chemical Engineering 2019年第1期27卷 174-181页

作者： zhiguo yan Sai Tang Xumiao Zhou Li yang Xingqing Xiao Houyang Chen Yuanhang Qin Wei Sun Key Laboratory of Green Chemical Process of Ministry of Education Key Laboratory of Novel Reactor and Green Chemical Technology of Hubei ProvinceSchool of Chemical Engineering and PharmacyWuhan Institute of Technology Department of Chemical and Biomolecular Engineering North Carolina State University Department of Chemical and Biological Engineering State University of New York at Buffalo

The exhaust gases, including SO_2,NH_3, H_2S, NO_2, NO, and CO, are principal air pollutants due to their severe harms to the ecological environment.Zeolites have been considered as good absorbent candidates to capture the six exhaust gases.In this work, we performed grand canonical ensemble Monte Carlo(GCMC) simulations to examine the capability of 95 kinds of all-silica zeolites in the removal of the six toxic gases, and to predict the adsorption isotherms of the six gases on all the zeolites.The simulation results showed that, H_2S, NO, NO_2, CO and NH_3 are well-captured by zeolite structures with accessible surface area of 1600–1800 m^2·g^(-1) and pore diameter of 0.6–0.7 nm, such as AFY and PAU, while SO_2 is well-adsorbed by zeolites containing larger accessible surface area(1700–2700 m^2·g^(-1)) and pore diameter(0.7–1.4 nm) at room temperature and an atmospheric pressure.However, at saturated adsorption, zeolites RWY, IRR, JSR, TSC, and ITT are found to exhibit better abilities to capture these gases.Our study provides useful computational insights in choosing and designing zeolite structures with high performance to remove toxic gases for air purification, thereby facilitating the development and application of exhaust gas-processing technology in green industry.

关键词： All-silica zeolites Toxic gases Adsorption isotherm GCMC simulation

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新发展阶段城市地下空间开发利用发展战略研究

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中国工程科学 2024年第3期26卷 176-185页

作者：彭芳乐乔永康董蕴豪闫治国朱合华同济大学土木工程学院上海200092 同济大学地下空间研究中心上海200092

作为城市建设和国土空间资源的重要组成部分,城市地下空间开发利用在新发展阶段的地位和作用愈显突出。本文通过剖析新发展阶段的新需求和新问题,提出了城市地下空间开发利用的新发展策略。基于国土空间规划新体系,绿色、低碳、韧性新... 详细信息

作为城市建设和国土空间资源的重要组成部分,城市地下空间开发利用在新发展阶段的地位和作用愈显突出。本文通过剖析新发展阶段的新需求和新问题,提出了城市地下空间开发利用的新发展策略。基于国土空间规划新体系,绿色、低碳、韧性新理念以及土地存量更新的新模式等新发展阶段的特征和要求,分析了城市高质量发展对地下空间开发利用的战略需求;提出了新发展阶段城市地下空间开发利用需要解决的一系列新生问题,包括国土空间资源禀赋调查评价不足、承载能力概念不清,城市地下空间的绿色低碳韧性挖潜不充分,城市地下基础设施资源配置不均衡、发展机理机制不明确等。在此基础上,从治理体系建设、资源智慧管理、规划理论方法、数据驱动范式、深层空间利用、存量空间重构、新区一体化开发及地铁域控制等8个方面阐释了新发展阶段城市地下空间开发利用的重点任务和发展建议,以期为实现城市地下空间的立法为本、规划引领、建设有序和智慧管理提供有益借鉴。

关键词：城市地下空间国土空间规划低碳韧性存量更新智能规划

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碳氢曲线下大直径盾构隧道结构热力特性

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隧道与地下工程灾害防治 2024年第2期6卷 25-36页

作者：闫治国王紫锐沈奕刘康同济大学土木工程学院地下建筑与工程系同济大学土木工程防灾减灾全国重点实验室

以济南某大直径隧道为研究对象，研究盾构隧道在火灾作用下温度场分布、结构变形以及内力分布规律，建立盾构隧道的全尺寸数值分析模型，提出盾构隧道衬砌结构的热-力耦合分析方法。研究结果表明：火灾作用下，内表面受火区域的温度明... 详细信息

以济南某大直径隧道为研究对象，研究盾构隧道在火灾作用下温度场分布、结构变形以及内力分布规律，建立盾构隧道的全尺寸数值分析模型，提出盾构隧道衬砌结构的热-力耦合分析方法。研究结果表明：火灾作用下，内表面受火区域的温度明显高于外表面，衬砌在距离内表面300 mm的部分基本不受火灾影响；衬砌结构受热发生膨胀变形，拱顶和拱底的变形逐渐降低，拱腰的水平方向变形不断增加，且部分管片接头明显张开；衬砌逐渐从受火面开始进入屈服状态，混凝土出现了应力重分布现象，连接处螺栓在高温作用下发生局部屈服；衬砌结构整体轴力下降并且弯矩剧烈增大，拱腰位置的弯矩比火灾前增大近一倍。

关键词：盾构隧道数值模拟火灾热力耦合力学特性

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Na^(+),K^(+)//CO_(3)^(2-),SO_(4)^(2-)-H_(2)O四元水盐体系相平衡综合实验设计

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实验室研究与探索 2024年第5期43卷 192-195,229页

作者：杨小俊于雪松龚美玲王雪茹闫志国武汉工程大学化工与制药学院磷资源开发利用教育部工程研究中心武汉430205

针对相平衡理论知识抽象难懂,相律、相图等内容难教难学的问题,设计了四元水盐体系相平衡综合实验。采用等温溶解平衡法研究了353~373 K下交互四元体系Na^(+),K^(+)//CO_(3)^(2-),SO_(4)^(2-)-H_(2)O的固液相平衡,并绘制出等温干基相图... 详细信息

针对相平衡理论知识抽象难懂,相律、相图等内容难教难学的问题,设计了四元水盐体系相平衡综合实验。采用等温溶解平衡法研究了353~373 K下交互四元体系Na^(+),K^(+)//CO_(3)^(2-),SO_(4)^(2-)-H_(2)O的固液相平衡,并绘制出等温干基相图和对应水图,确定硫酸钠相区随着温度的增加而上移。依据相图指导碱灰溶解-蒸发结晶工艺设计,解决了高CO_(3)^(2-)浓度下结晶参数的优化问题,实现Na2SO4在高温下溶解,随后降温结晶析出的循环回收过程。该实验将相平衡数据的测量、相图的绘制、相图的分析融合一体,有利于增强学生用相平衡基本理论解决工程问题的能力,实现对理论知识的融会贯通,激发其科研兴趣和探索精神。

关键词：综合实验相平衡水盐体系结晶

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安徽省永久性测量标志保护成果验收规范研究

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安徽地质 2024年第2期34卷 148-152页

作者：王芳刘磊陆齐严志国安徽省测绘产品质量监督检验站安徽合肥230031 安徽省基础测绘信息中心安徽合肥230031 六安市地理信息和土地整理中心安徽六安237000

本文结合安徽省永久性测量标志保护工作,阐述了当前国内测量标志保护工作的必要性和重要性,介绍了安徽省测量标志保护工作开展中存在缺乏相关的质量管理规程、规范来统一标志保护工作的作业方式、流程和要求的现状。提出检验组织建设原... 详细信息

本文结合安徽省永久性测量标志保护工作,阐述了当前国内测量标志保护工作的必要性和重要性,介绍了安徽省测量标志保护工作开展中存在缺乏相关的质量管理规程、规范来统一标志保护工作的作业方式、流程和要求的现状。提出检验组织建设原则、检验内容和方法,对检验的流程进行了探讨,分析了检验工作中的质量元素及相关的质量评定,以提供给相关工作人员参考和借鉴。旨在有效保障测量标志保护工作实施,优化保护工作流程,提升测量标志保护能力,为实现测量标志的科学规划、动态管理、有效管护、高效服务提供高质量组织保障和技术支撑。

关键词：测量标志质量元素样本批次成果检查验收

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