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Performance and environmental impacts of deep foundation excavation in soft soils:A field and modeling-based case study in Nanjing,China

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Underground Space 2024年第5期18卷 218-238页

作者： Chenhe Ge Meng Yang Pengfei Li Mingju Zhang Zhonghao Zhang Key Laboratory of urban Security and Disaster engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China China construction Second engineering Bureau Ltd. Beijing 100070China The Third construction engineering Company Ltd.of China construction Second engineering Bureau Beijing 100070China

This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical *** tests were conducted to determine the soil parameters used in the modified Cam–Clay(MCC)*** field monitoring means were adopted and a three-dimensional model was *** and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft *** characteristics of the enclosure structure and the surrounding environment throughout the excavation process are *** behaviors of diaphragm walls,columns,the maximum wall deflection rate,ground surface settlement,and utility pipelines were focused on and investigated during the whole excavation ***,the axial forces of the internal supports are *** on the measured and simulated data,the following main conclusions were obtained:the numerical simulation results are in good agreement with the measured values,which proves the accuracy of the model parameters;the wall and the ground surface showed the maximum displacement increment at stage 9,which was a coupled product of the"creep effect"of the soft soil in Nanjing,China and the"depth effect"of the excavation;as the excavation progressed,the ground settlement changed from a"rising"to a"spoon-shaped"trend,dvm was measured betweenδ_(vm)=0.0686%H andδ_(vm)=0.1488%H;the rebound deformation curve of the pit bottom was corrugated,and the depth of disturbance of the pit bottom after the completion of soil unloading was 2–3 times the excavation depth;the closer the pipeline is to the corner of the pit,the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur;the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.

关键词： Deep excavation Modified Cam-Clay Deformation characteristics Creep effect Corner effect

Single-atom catalysis for advanced oxidation and reduction systems in water decontamination

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Rare Metals 2024年第8期43卷 3576-3606页

作者： Jie Teng Jin-Hui Xu Wen-Xin Sun Xue-Feng Liu Xia Xu Guo-Shuai Liu School of urban construction Changzhou UniversityChangzhou 213164China School of Environmental and Civil engineering Jiangnan UniversityWuxi 214122China

Water scarcity is an escalating global crisis,posing a severe threat to populations ***,exploring various materials to remove emerging contaminants from freshwater sources has garnered significant *** this regard,single-atom catalysis(SACs) has emerged as a catalyst of scientific progress in water purification and treatment methodologies during recent *** exhibit exceptional catalytic activity,selectivity and stability,due to their near-perfect atom utilization,highly unsaturated coordination environment and uniform reaction ***,a comprehensive and critical review encompassing the successful integration of SACs into water purification processes needs to be *** review aims to accentuate recent trends by presenting the synthesis,structure,and environment and energy application-relevant properties of *** results show that a comprehensive and multi-perspective summary of the advantages of SACs in environmental remediation can have significant benefits,such as fast kinetics,costeffectiveness,*** oxidation and reduction processes of SACs and functional SACs materials in water purification were ***,the last section is devoted to the current research gaps and further perspectives on the application of SACs in water treatment,which are summarized and analyzed.

关键词： Single-atom catalysis Water treatment Oxidation Reduction

Influence of crystal-transforming agent on the performance and mechanism ofα-high-strength gypsum prepared from FGD gypsum

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Particuology 2024年第4期87卷 37-45页

作者： Zhuoyue Xu Xiao Wang Biao Jin Dawang Zhang Hui Li College of Materials Science and engineering Xi'an University of Architecture and TechnologyXi'an710055China Schoolof Materials and Chemical engineering Henan University of Urban ConstructionPingdingshan46736China

This paper investigates the impact of flue gas desulfurization(FGD)gypsum's crystal modifier on the characteristics and microcosmic mechanism ofα-high strength *** results demonstrate that all three crystal modifiers can convert FGD gypsum toα-high-strength *** acid(CA)has the most significant influence onα-high-strength gypsum,and the preparedα-high-strength gypsum is short columnar,with an aspect ratio in the range of 1-3,and has a faster setting time,a larger specific surface area,and a smaller standard consistency,higher compressive strength,greater surface hardness,and smaller crystal particle *** initial setting time of theα-high-strength gypsum manufactured with CA crystal modifier was decreased by 36%compared to the blank sample,the final setting time was lowered by 37.5%,and the water consumption of the standard consistency was reduced by 8%.The maximum strength is 32 MPa after 2 h,the absolute dry compressive strength is up to 38 MPa,and the surface hardness is improved by 24.43%.

关键词： Flue gas desulfurization gypsum Crystal modifier Microscopic mechanism α-high-strength gypsum

Effect of the Retarder on Initial Hydration and Mechanical Properties of the"one-step"Alkaliactivated Composite Cementitious Materials

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1199-1213页

作者： DING Rui HE Yue LI Xingchen LI Han TIAN Hao WANG Hongen School of Materials Science and engineering Jilin Jianzhu UniversityChangchun 130118China Ziyang urban construction Investment Group Co. LtdNanchong 637000China Shandong Taihe urban construction Development Co. Ltd.Jining 272000China

This paper studied the effects of different retarders on the performance of the"one-step"alkali-activated composite cementitious material(ACCM)which is composed of ground granulated blast slag(GGBS)and fly ash(FA),and analyzed its mechanical properties,hydration mechanism,and retardation *** effects of retarders on the hydration products,mechanical properties,and hydration kinetics of ACCM were investigated using XRD,SEM,FTIR,EDS,and thermoactive *** results showed that Na_(2)B_(4)O_(7)·10H_(2)O(B)delayed the exotherm during the alkali activation process and could effectively delay the setting time of ACCM,but the mechanical properties were slightly *** setting time of ACCM increased with the increase in SG content,but the mechanical properties of ACCM decreased with the increase in SG content.C1_(2)H_(22)O_(11)(CHO)could effectively delay the hydration reaction of ACCM and weakly enhanced the compressive strength.H_(3)PO_(4)(HP)at a concentration of 0.05 mol/L had a certain effect on ACCM retardation,but HP at a concentration of 0.07 and 0.09 mol/L had an effect of promoting the setting and hardening time of ACCM.

关键词： "one-step"alkali-activated composite cementitious materials solid activator hydration mechanism retarder retarding mechanism

The Application of Solid Waste in Thermal Insulation Materials: A Review

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Journal of Renewable Materials 2024年第2期12卷 329-347页

作者： Ming Liu Pinghua Zhu Xiancui Yan Haichao Li Xintong Chen School of Environmental Science and engineering Changzhou UniversityChangzhou213164China School of urban construction Changzhou UniversityChangzhou213164China

As socioeconomic development continues,the issue of building energy consumption has attracted significant attention,and improving the thermal insulation performance of buildings has become a crucial strategic ***,the application of solid waste in insulation materials has also become a hot *** paper reviews the sources and classifications of solid waste,focusing on research progress in its application as insulation materials in the domains of daily life,agriculture,and *** research shows that incorporating household solid waste materials,such as waste glass,paper,and clothing scraps into cementitious thermal insulation can significantly reduce the thermal conductivity of the materials,leading to excellent thermal insulation *** materials prepared from agricultural solid waste,such as barley straw,corn stalk,chicken feather,and date palm fibers,possess characteristics of lightweight and strong thermal *** solid waste,including waste tires,iron tailings,and coal bottom ash,can also be utilized in the preparation of insulation *** innovative applications not only have positive environmental significance by reducing waste emissions and resource consumption,but also provide efficient and sustainable insulation solutions for the construction ***,to further optimize the mix design and enhance the durability of insulation materials,continuous research is required to investigate the mechanisms through which solid waste impacts the performance of insulation materials.

关键词： Solid waste building energy consumption insulation material sustainability

A theoretical study on gaseous pollutant flushing of natural ventilation driven by buoyancy forces in industrial buildings

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Building Simulation 2024年第4期17卷 575-589页

作者： Jiawei Zhuang Genyang Chen Rumeng Yang Kun Han Dongdong Tian Yongfa Diao Henggen Shen School of urban construction Changzhou UniversityChangzhou213164China School of Petroleum and Natural Gas engineering School of EnergyChangzhou UniversityChangzhou213164China College of Environmental Science and engineering Donghua UniversityShanghai201620China School of Architecture and urban Planning Nanjing UniversityNanjing210093China

The acceleration of industrialization worsening indoor environments of industrial buildings has drawn more attention in recent *** ventilation can improve indoor air quality(IAQ)and reduce carbon *** evaluate gaseous pollutant levels in industrial buildings for the development of buoyancy-driven natural ventilation,two theoretical models of pollutant flushing(Model I and Model II)are developed based on the existing thermal stratification theory in combination with the mixing characteristics of lower *** results show that indoor pollutant flushing is mainly dependent on the pollution source intensity and effective ventilation *** mixing characteristics of lower pollutant has an important effect on pollutant stratification and evolution during ventilation,but it does not change the prediction results at steady *** the dimensionless pollution source intensity is larger than 1,the pollution source should be cleaned up or other ventilation methods should be used instead to improve *** addition,the comparisons between Model I and Model II on instantaneous pollutant concentration are significantly influenced by the pollution source intensity,and the actual pollutant concentration is more likely to be between the predicted values of Model I and Model *** reduce pollutant concentration to a required level,the pollution source intensity should be in a certain *** theoretical models as well as the necessary conditions for ventilation effectiveness obtained can be used for the ventilation optimization design of industrial buildings.

关键词： industrial buildings buoyancy-driven natural ventilation gaseous pollutants evolution model pollution sources

Effect of local openings on bearing behavior and failure mechanism of shield tunnel segments

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Underground Space 2024年第3期16卷 183-205页

作者： Xiaojing Gao Pengfei Li Mingju Zhang Haifeng Wang Ziqi Jia Wu Feng Key Laboratory of urban Security and Disaster engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China Nantong Railway construction Component Co. LtdNantong 226000China

Local failures(loss of concrete or reinforcement)can severely compromise the bearing capacity of shield segments,damaging the tunnel *** investigate the effects of local openings on the bearing behavior and failure mechanism,four full-scale bending tests were conducted on specimens with different opening positions and diameters;monitoring of load,displacement,and concrete strain was performed during *** test results reveal that both the opening position and diameter significantly influence the bearing characteristics of the *** failure process includes four sequential stages distinguished by three critical loads,namely the cracking,failure,and ultimate ***,the numerical model of the local failure segment was established using the elastoplastic damage constitutive relation of the concrete and verified by inversing the full-scale test *** on the numerical model,parametric analyses were performed to comprehensively investigate the influences of the opening position,concrete loss,and reinforcement loss on the bending ***,an analytical model was proposed,indicating that the opening position is the primary factor decreasing the bearing capacity,followed by the opening diameter and reinforcement *** results of this study can provide a theoretical basis for the safety assessment and remedial design of subway shield tunnels under extreme breakthrough conditions.

关键词： Shield tunnel Local opening segment Bearing behavior Failure mechanism

Numerical manifold method for steady-state nonlinear heat conduction using Kirchhoff transformation

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Science China(Technological Sciences) 2024年第4期67卷 992-1006页

作者： ZHANG LiMei KONG Heng ZHENG Hong Key Laboratory of urban Security and Disaster engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China Beijing Municipal construction Co. Ltd.Beijing 100048China

The numerical manifold method(NMM)introduces the mathematical and physical cover to solve both continuum and discontinuum problems in a unified *** this study,the NMM for solving steady-state nonlinear heat conduction problems is presented,and heat conduction problems consider both convection and radiation boundary ***,the nonlinear governing equation of thermal conductivity,which is dependent on temperature,is transformed into the Laplace equation by introducing the Kirchhoff *** transformation reserves linearity of both the Dirichlet and the Neumann boundary conditions,but the Robin and radiation boundary conditions remain ***,the NMM is employed to solve the Laplace equation using a simple iteration procedure because the nonlinearity focuses on parts of the problem domain ***,the temperature field is retrieved through the inverse Kirchhoff *** examples are analyzed,demonstrating the advantages of the Kirchhoff transformation over the direct solution of nonlinear equations using the NewtonRaphson *** study provides a new method for calculating nonlinear heat conduction.

关键词： numerical manifold method nonlinear heat conduction temperature-dependent thermal conductivity Kirchhoff transformation convection and radiation boundary conditions

Simplified seismic scenario analysis of existing masonry buildings accounting for local site effects

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Frontiers of Structural and Civil engineering 2024年第2期18卷 309-318页

作者： Ayşe E.ÖZSOYÖZBAY Işıl SANRI KARAPINAR Zehra N.KUTLU İsmail E.KILIÇ department of Civil engineering Maltepe UniversityIstanbul 34857Turkey School of engineering and construction Oryx Universal CollegeDoha 12253Qatar

This study discusses the effects of local sites and hazard amplification on the seismic vulnerability assessment of existing masonry *** this context,a rapid seismic evaluation procedure was implemented on an old masonry building stock in the historical center Galata,located inİstanbul,to determine the seismic risk priority of the built *** scenarios were generated for all soil classes,different moment magnitudes,and source-to-site distances to obtain more accurate results for the seismic vulnerability assessment of the studied building ***,damage distributions estimated under nine different scenarios with/without site effects were compared and illustrated in maps to discuss changes in vulnerability owing to amplification *** this study,by re-examining the rapid seismic evaluation procedure by including geo-hazard-based assessment,the importance of site effects on the vulnerability and risk assessment of built heritage was *** proposed framework integrating field data and local site effects is believed to advance the current applications for vulnerability assessment of masonry buildings and provide an improvement in the application of rapid seismic assessment procedures with more reliable results.

关键词： masonry buildings seismic vulnerability assessment cultural heritage local site effect