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Effect of activator on rheological properties of alkali-activated slag-fly ash pastes

Journal of Central South University 2022年第1期29卷 282-295页

作者： YUAN Qiang HUANG Yan-ling HUANG Ting-jie YAO Hao WU Qi-hong School of Civil Engineering Central South UniversityChangsha 410075China National Engineering Research Center of of High Speed Railway Construction Technology Changsha 410075China School of Architecture and Civil Engineering Chengdu UniversityChengdu 610106China

The time-dependent rheological behaviors of alkali-activated cement(AAC)are expected to be precisely controlled,in order to meet the requirements of modern engineering *** this paper,the effects of activator,including the Na_(2)O concentration and SiO_(2)/Na_(2)O(S/N)molar ratio,on the rheological behavior of alkali-activated slag fly ash pastes were *** small amplitude oscillatory shear(SAOS)and shear test were used to evaluate the structural build-up and flowability of ***,zeta potential measurement,calorimetric test and thermogravimetric analysis(TGA)were carried out to reveal the physico-chemical mechanisms behind the rheological evolution of fresh *** was found that high Na_(2)O concentration and low S/N molar ratio improved the flowability and structural build-up rate of ***,the structural build-up of alkali-activated slag-fly ash pastes consists of two stages,which is controlled by the dissolution of solid reactants and formation of C-(A)-S-H gels,respectively.

关键词： alkali-activated slag-fly ash activator zeta potential rheology structural build-up

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Horizontal Response of Existing Pile Induced by Adjacent Shield Tunnelling with Large Longitudinal Slope

SSRN

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SSRN 2024年

作者： Liu, Weizheng Wang, Mingye Luo, Guijun Lu, Weihua Xiao, Hongbo School of Civil Engineering Central South University Changsha410075 China China Construction Fifth Engineering Division Civil Engineering Co. Ltd. Changsha410075 China School of Civil Engineering Nanjing Forestry University Nanjing210037 China National Engineering Research Center of High-Speed Railway Construction Technology Changsha410075 China

The horizontal displacement and bending moment of an existing pile due to adjacent shield tunnelling with a large longitudinal slope were analysed. An analytical calculation method for the horizontal response of adjacent shield tunnelling to an existing pile was presented, considering the included angle between the axis of the tunnel and the horizontal plane, the tunnel-soil-pile interaction, and the shielding effect of the pile group. A new formula for soil horizontal deformation was derived by combining the cutterhead additive thrust force, the frictional force between the shield and the soil, the additional grouting pressure and the soil loss;subsequently, the pile response was calculated as it was subjected to the generated ground displacement. The reliability of the analytical method in this paper was verified by comparing the existing analytical solution, field monitoring data, and finite element model results. The proposed method was employed to reveal the variation law of the horizontal response of the pile during the shield tunnelling process. A parametric analysis of the longitudinal slope angle, shield tunnelling parameters, and soil modulus was also conducted to assess their influences on tunnelling-induced pile deflection and bending moment. The results show that the increase in the longitudinal horizontal response of the pile along the tunnelling direction is more prominent before the shield arrives at the pile side, moreover, the instant peak values of the horizontal response of the pile increase with increasing longitudinal slope angle, and its position moves downwards. The shield arrives at the pile side, the increase in the longitudinal horizontal response of the pile reaches the maximum value, moreover, the influence of changes in the longitudinal slope angle on the horizontal response of the pile foundation is not significant. The transverse horizontal response of the pile changes more after the shield passes through the pile and shows an increas

关键词： Piles

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Thermal and mechanical characteristics of a thermal pile in permafrost regions

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Advances in Climate Change Research 2023年第2期14卷 255-266页

作者： Yun-Hu SHANG Fu-Jun NIU Kun YUAN Tian SUN Li-Bo WU State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Da Xing'anling Observation and Research Station of Frozen-Ground Engineering and Environment Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesJiagedaqi 165000China First Highway Consultants Co. Ltd.China Communications Construction Company LimitedXi'an 710075China Jiangsu Sunpower Technology Co. Ltd.Nanjing 210009China School of Civil Engineering and Hydraulic Engineering Ningxia UniversityYinchuan 750021China

Cast-in-place pile foundations are widely used in permafrost regions to support *** stability of cast-in-place pile foundations is highly sensitive to permafrost thermal regime *** degradation caused by climate change is increasing the disaster risk of castin-place pile ***,proactive cooling methods for cast-in-place pile foundations are seldom *** cold energy produced by two-phase closed thermosyphons(TPCTs)can efficiently prevent the permafrost thermal regime from being disturbed by engineering activities and climate *** were installed in a concrete pile forming a thermal ***,a model experiment was conducted to explore the thermal regime,influence scope,dissipation process of cold energy,and freezing strength of the thermal *** results indicated that the thermal pile may significantly cool the foundation *** of cold energy produced by the thermal pile dissipated during the warm period,and the cooling scope of the thermal pile can cover the area within a 40 cm(twice the pile diameter)radius around the ***,the TPCTs can significantly improve freezing strength between the thermal pile and frozen *** lesson learned from this study can provide a new approach to control the thermal regime of cast-in-place pile foundation in permafrost,which was of valuable to the construction of pile foundations in cold regions.

关键词： Pile foundation Cold energy Two-phase closed thermosyphon Freezing strength Permafrost regions

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Study on the structure of offshore wind and solar hybrid power generation device under the background of green energy

Study on the structure of offshore wind and solar hybrid pow...

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作者： Hansheng Wang Yanbin Yang Shujun Zhang Department of Construction Management Xi'an University of Architecture and Technology Department of Civil Engineering Tianjin University Department of Civil Engineering Chang'an University

There are sufficient solar and wind energy in the sea,which can be used as a good power generation energy and obtain great energy ***,the development of offshore green energy has become the mainstream *** paper mainly focuses on the study of offshore wind solar energy generation *** paper first introduces the principle of wind power generation and photovoltaic power generation and the existence of a large amount of energy offshore,and then leads to the basic structure of wind-solar hybrid power generation *** it further studies the power generation,wind load,wave load,initial stability and economic ***,the advantages and future environmental benefits of the structure are summarized,and the structure is reformed *** results show that the structure has good stability,load bearing capacity and economy,and the construction difficulty of the improved structure has been reduced.

关键词： clean energy structure of wind and solar energy offshore

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Numerical analysis of SCF of Tubular T-joints strengthened with prestressed CFRP

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Procedia Structural Integrity 2024年 64卷 1865-1872页

作者： Yuan Xu Qian-Qian Yu Guo-Wen Xu Tongji University Shanghai 200092 China China Construction Eighth Engineering Division Co. Ltd. Shanghai 200122 China Shanghai Engineering Research Center of CFRP Application Technology in Civil Engineering Shanghai 200122 China

Fatigue failure is one of the main concerns of welded tubular joints owing to inevitable welding defects and severe stress concentration along the intersection. In addition, the complex geometry of the joint makes it inconvenient to reinforce by traditional repair methods. Carbon fiber-reinforced polymer (CFRP) composite has been widely used for structural strengthening due to superior strength-to-weight ratio, good fatigue and corrosion resistance, as well as ease of installation. Although tubular joints strengthened by using non-prestressed CFRP sheets have been investigated in references, application of prestressed CFRP has not been reported. This study proposed a form of prestressed CFRP sheets for the fatigue strengthening of tubular T-joints. Three-dimensional finite element models were developed for both CFRP-strengthened and unstrengthened tubular T-joints to calculate the hot spot stress distribution, which was verified using experimental test data and Lloyd’s Register (LR) equations. A parametric study was then carried out to explore effects of CFRP strengthening parameters on the SCF reduction coefficient ψ , including the prestressing level ( p ), CFRP width ( w ), and CFRP layers ( n ). It was found that prestressing CFRP changed the stress distribution and values along the weld toe. With the increase of prestress, the position of the maximum stress gradually moved from the saddle point to the crown point. Besides, the strengthening parameters had significant effects on reduction of the hot spot stress along the weld toe.

关键词： Prestressed CFRP CFRP strengthening Circular hollow section T-joints Finite element analysis SCF reduction coefficient

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Mechanical Properties of Steel Fiber Reinforced Concrete Tunnel Secondary Lining Structure and Optimization of Support Parameters

SSRN

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SSRN 2025年

作者： Wang, Zijian Wang, Yunchuan Wang, Xiaorong Rong, Baosheng Zhang, Bin Wu, Liming Jia, Chaolin Huang, Zihang School of Civil and Hydraulic Engineering Chongqing University of Science and Technology 401331 China School of Urban Construction Engineering Chongqing Technology and Business Institute 400052 China Chongqing Chuanjiu Construction Co. Ltd. 401120 China

To improve the economic and safety aspects of tunnel structure design, this paper studies the mechanical properties of steel fiber reinforced concrete (SFRC) secondary lining structures and optimizes support parameters based on optimized SFRC mix proportions. The research involves scaled model experiments and finite element analysis to study the cracking process, deformation characteristics, and stress distribution of SFRC tunnel secondary linings under different loading *** ABAQUS software, simulations were conducted on SFRC linings with thicknesses of 350mm, 400mm, 450mm, 500mm, 550mm, and 600mm, and reinforcement ratios of 0%, 0.04%, 0.08%, 0.12%, 0.16%, 0.20%, 0.24%, and 0.28%. The results indicated that the 450mm thick SFRC lining had comparable overall mechanical performance to a 600mm thick ordinary reinforced concrete lining. The incorporation of steel fibers significantly improved the deformation resistance and crack resistance of the lining. Specifically, when the circumferential reinforcement ratio of SFRC lining is 0.20%, its overall mechanical performance is equivalent to that of a conventional concrete lining with a reinforcement ratio of 0.28%. © 2025, The Authors. All rights reserved.

关键词： Cracks

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Long Term Seasonal Rainfall Forecasting using Artificial Neural Network: Case Study of Northern Territory, Australia 40

Long Term Seasonal Rainfall Forecasting using Artificial Neu...

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40th Hydrology and Water Resources Symposium, HWRS 2022

作者： Rashid, Farooq Fatemeh, Mekanik Monzur, Imteaz Department of Civil and Construction Engineering Swinburne University of Technology Melbourne VIC 3122 Australia Melbourne Australia Department of Civil Engineering International Islamic University Islamabad 44000 Pakistan Islamabad Pakistan Bureau of Meteorology Australia Australia

ISBN: (纸本)9781925627640

El Nino southern Oscillation (ENSO), Madden Julien Oscillation (MJO) and Indian Ocean Dipole (IOD) have enormous effects on the precipitations around the world. Australian rainfall is also affected by these key modes of complex climate variables. Many studies have tried to establish the relationships of these large-scale climate indices with the rainfalls of different parts of Australia. Unlike the other regions, no clear relationship can be found between each individual large-scale climate mode and rainfall around Northern Territory (NT). This study investigates the lagged-time relationships of these modes on NT's wet period rainfall i.e., from October to April. On the other hand, few attempts have been made to establish the combined effect of these indices on rainfall to develop a better understanding and forecasting system. Since rainfall is a complicated atmospheric phenomenon, linear techniques might not be sufficient to capture its characteristics. This research attempts to find a nonlinear relationship between the NT rainfall and the lagged indices affecting the region using Artificial Neural Networks (ANN). It was discovered that ANN modelling can provide higher correlations using the lagged indices in forecasting wet period rainfall in compared to linear methods. Using these indices in an ANN model increased the model correlation up to 91%, and 90% for the two case study stations of Darwin and East Arnham in NT, respectively. Moreover, Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Pearson correlation coefficient (r) skill scores are used to evaluate the performance of the proposed models. It is found that MJO and IOD indices have higher effects on the centre and west of NT more than the ENSO, while ENSO seems to have a stronger effect on the eastern side. © Hydrology and Water Resources Symposium, HWRS 2022. All rights reserved.

关键词： Rain

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Recent Progress in Net-Zero-Energy Buildings in Tropical Climates: A Review of the Challenges and Opportunities 1st

Recent Progress in Net-Zero-Energy Buildings in Tropical Cli...

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1st International Conference on Net-Zero Built Environment: Innovations in Materials, Structures, and Management Practices, NTZR 2024

作者： Mengaw, Mengesha Asefie Mengesha, Wubishet Jekale Madessa, Habtamu Bayera Addis Ababa Science and Technology University Department of Civil Engineering Addis Ababa Ethiopia Addis Ababa University Ethiopian Institute of Architecture Building Construction and City Development Addis Ababa Ethiopia Oslo Metropolitan University Department of Built Environment Oslo Norway

ISBN: (纸本)9783031696251

Buildings account for a significant proportion of the total energy consumption in the global energy sector, with a value of about 40% of the total energy consumption and greenhouse gas emissions, and studying building energy can play a crucial role in shaping sustainable development goals (SDGs). Interest in achieving net-zero and positive-energy buildings has been growing in recent years. Recent research publications to this day exhibit a lack of focus on net-zero-energy buildings (NZEBs);a more comprehensive literature would include the challenges and opportunities of such buildings. For this reason, this chapter aims to provide a comprehensive up-to-date review of the recent progress, challenges, and opportunities in constructing net-zero-energy buildings in tropical climates. The findings show that the opportunities for constructing net-zero-energy buildings in tropical climates include, but are not limited to, the availability of solar energy, government policies and incentives promoting NZEBs, monetary benefits from increasing the demand for energy-efficient buildings, creating employment opportunities in research and development, reducing operational energy costs, and decreasing the carbon emissions of buildings. On the other hand, the challenges to constructing NZEBs in tropical climates are their high initial costs, regulations and policies, technological barriers to developing energy-efficient materials that are both cost-effective and readily available, connecting net-zero-energy buildings to smart grids, environmental and socioeconomic concerns, occupant behavior, and retrofitting existing buildings. © The Author(s) 2025.

关键词： Green buildings

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Heavy metal removal from aqueous solutions by chitosan-based magnetic composite flocculants

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Journal of Environmental Sciences 2021年第10期33卷 22-32页

作者： Xuefeng Xiao Yuanyuan Yu Yongjun Sun Xing Zheng Aowen Chen College of Urban Construction Nanjing Tech UniversityNanjing 211800China Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China

In this study,three magnetic flocculants with different chelating groups,namely,carboxymethyl chitosan-modified Fe_(3)O_(4)flocculant(MC),acrylamide-grafted magnetic carboxymethyl chitosan flocculant(MCM),and 2-acrylamide-2-methylpropanesulfonic acid copolyacrylamide-grafted magnetic carboxymethyl chitosan flocculant(MCAA)were prepared,synthesized,and characterized by photopolymerization *** were applied to the flocculation removal of Cr(Ⅲ),Co(Ⅱ),and Pb(Ⅱ).The effect of flocculation condition on the removal performance of Cr(Ⅲ),Co(Ⅱ),and Pb(Ⅱ)was *** results show that the three magnetic carboxymethyl chitosan-based flocculants have been successfully prepared with good magnetic induction *** results show that the removal rates of MC,MCM,and MCAA on Cr(Ⅲ)are 51.79%,82.33%,and 91.42%,respectively,under the conditions of 80 mg/L flocculant,pH value of 6,reaction time of 1.5 hr,G value of 200 s^(-1),and precipitation magnetic field strength of 120 *** removal rates of Co(Ⅱ)by MC,MCM,and MCAA are 54.33%,84.99%,and 90.49%,*** removal rates of Pb(Ⅱ)by MC,MCM,and MCAA are 61.54%,91.32%,and 95.74%,*** shows good flocculation performance in composite heavy metal-simulated *** magnetic carboxymethyl chitosan-based flocculant shows excellent flocculation performance in removing soluble heavy *** research provides guidance and ideas for the development of efficient and low-cost flocculation technology to remove heavy metals in wastewater.

关键词： Flocculant Carboxymethyl chitosan Magnetic flocculants Heavy metal Flocculation

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Intelligent control of air conditioning in exhibition halls based on edge computing 4

Intelligent control of air conditioning in exhibition halls ...

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4th International Conference on Machine Learning and Computer Application, ICMLCA 2023

作者： Su, Hexuan Yu, Wenhong Zou, Songling Wang, Kuan School of Civil Engineering North China University of Technology Beijing China China Railway Construction Group Co. Ltd Beijing China Carbon Neutral Research Institute of Boao Hainan China

ISBN: (纸本)9798400709449

This paper proposes a new method of achieving air conditioning energy conservation in small and medium-sized exhibition halls by utilizing infrared sensors, pressure sensors, and edge computing control. This paper firstly introduces the special characteristics of small and medium-sized exhibition halls, then it introduces edge computing technology from the aspects of data prediction and data acquisition and realizes the intelligent control of air conditioning to achieve the energy-saving goal by using temperature sensors and pressure sensors for edge computing. Finally, a case study is presented, indicating that implementing an edge control system in the air conditioning of small and medium-sized exhibition halls can reduce overall energy consumption by 15%-20%. © 2023 ACM.

关键词： Air conditioning

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