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Acoustic emission characteristics of damage evolution of multi-scale fiber reinforced rubberized concrete under uniaxial compression and tension after being subjected to high temperatures

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Frontiers of Structural and Civil Engineering 2024年第8期18卷 1237-1266页

作者： Shaoqi ZHANG Yao ZHANG Qianru LEI Yumeng YANG Yichao WANG Fei XU Zhiguo YAN Hehua ZHU Laboratory of Fire Safety School of Safety Engineering and Emergency ManagementShijiazhuang Tiedao UniversityShijiazhuang 050043China Structural Health Monitoring and Control Key Laboratory of Hebei Province Shijiazhuang Tiedao UniversityShijiazhuang 050043China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

Recently developed multi-scale fiber(i.e.,CaCO3 whisker,polyvinyl alcohol(PVA)fiber,and steel fiber)reinforced rubberized concrete exhibits excellent mechanical properties and spalling resistance at high *** of macro properties such as strength and Young’s modulus cannot reveal and characterize damage mechanisms,particularly those relating to the multi-scale fiber strengthening *** this study,acoustic emission(AE)technology is applied to investigate the impact of multi-scale fiber on the damage evolution of rubberized concrete exposed to high temperatures,under the uniaxial compression and tension loading *** mechanical properties,AE event location,peak frequency,b-value,the ratio of rise time to amplitude(RA),average frequency(AF)values,and AE energy of specimens are *** results show that the number of events observed using AE gradually increases as the loading *** crumb rubber and fibers inhibit the generation and development of the *** is concluded that both the peak frequency and b-value reflect the extension process of *** the cracks develop from the micro scale to the macro scale,the peak frequency tends to be distributed in a lower frequency range,and the b-value decreases *** the peak stress point,the AE energy increases rapidly and the b-value *** specimens without multi-scale fibers exhibit brittle failure,while the specimens with fibers exhibit ductile *** addition,adding multi-scale fibers and crumb rubber increases the peak frequency in the medium and high frequency ranges,indicating a positive effect on inhibiting crack *** being subjected to high temperatures,the maximum and minimum b-values decrease,reflecting an increase in the number of initial cracks due to thermal ***,the RA and AF values are used to classify tensile and shear *** specimens fracture with more shear cracks under compression,and there are more tensile

关键词： multi-scale fibers acoustic emission fracture damage evolution rubberized concrete

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Temporal variation of PM_(2.5)-associated health effects in Shijiazhuang,hebei

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Frontiers of Environmental Science & Engineering 2021年第5期15卷 75-83页

作者： Aifang Gao Junyi Wang Jianfei Luo Aiguo Li Kaiyu Chen Pengfei Wang Yiyi Wang Jingyi Li Jianlin Hu Hongliang Zhang School of Water Resources and Environment Hebei GEO UniversityShijiazhuang050031China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologyNanjing University of Information Science&TechnologyNanjing210044China Hebei Province Collaborative Innovation Center for Sustainable Utilization of Water Resources and Optimization of Industrial Structure Hebei Province Key Laboratory of Sustained Utilization and Development of Water ResourcesShijiazhuang050031China Department of Civil and Environmental Engineering Louisiana State UniversityBaton RougeLA70803USA Department of Environmental Science and Engineering Fudan UniversityShanghai200438China

Shijiazhuang is one of the cities in the North China *** recent decades,this city has experienced high levels of fine particulate matter(PM_(2.5)),which have potentially significant effects on human *** this study,the health effects of PM_(2.5)exposure in Shijiazhuang were estimated by applying an integrated exposure-response *** mortality,years of life lost(YLL),and the mortality benefits linked to reduced levels of PM_(2.5)were quantified for the period 2015–*** 2015,2016,and 2017,cerebrovascular diseases caused the highest premature mortality(2432,2449,and 2483,respectively),followed by ischemic heart diseases(1391,1479,and 1493,respectively),lung cancer(639,660,and 639,respectively),and chronic obstructive pulmonary diseases(533,519,and 473,respectively).Notably,the total number of premature deaths caused by PM_(2.5)exposure in Shijiazhuang in 2015,2016,and 2017 were 4994,5107,and 5088,***,the YLL in the same years were 47001,47880 and 47381,***,the YLL per 1000 females was lower than that per 1000 ***,we noted that premature mortality and YLL decreased by 84.2%and 84.6%when the PM_(2.5)levels diminished to 10µg/m^(3).Overall,the results of this study improve our understanding of how high PM_(2.5)concentrations affect human health and suggest the application of more stringent measures in Shijiazhuang to alleviate the associated health risks.

关键词： PM_(2.5) health effects Integrated exposure-response model Shijiazhuang

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Full-Scale Cutting Experiments of Different Granite Integrity Using Tunnel Boring Machine Disc Cutter

SSRN

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SSRN 2022年

作者： Sun, Hao-Kai Gao, Yang Chen, Yong Geotechnical and Structural Engineering Research Center Shandong University Jinan250061 China Key Laboratory for Structure Health Monitoring and Control in Hebei Province Shijiazhuang Tiedao University Shijiazhuang050043 China

The complex geological conditions of tunnels with tunnel boring machine make geological exploration very difficult. To explore the method of predicting the rock mass integrity based on the cutterhead vibration signal, the mapping relationship between the rock mass integrity, cutter forces, and cutterhead vibration was studied by the full-scale rotary cutting machine. Our finding is that the mean amplitude, the single peak value of the normal force, and the RMS values of the cutterhead vibration all increase with ascending rock mass integrity. The average amplitude and single peak value decrease, and the RMS value increase with the increase of the rotation speed. The average amplitude increases, the single peak value decreases, and the RMS value increases as the advance speed increase. We demonstrated that there is an obvious corresponding relationship between the normal force and the vibration, and rock mass and operating parameters have significant effects on the vibration characteristics. © 2022, The Authors. All rights reserved.

关键词： Boring machines (machine tools)

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A long-term vertical displacement prediction method of concrete bridges based on meteorological shared data and optimized GRU model

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Measurement: Journal of the International Measurement Confederation 2025年 253卷

作者： Wang, Xu Xie, Guilin Liu, Wentao Kong, Hu Gao, Yang State Key Laboratory of Mountain Bridge and Tunnel Engineering Chongqing Jiaotong University Chongqing400074 China School of Civil Engineering Chongqing Jiaotong University Chongqing400074 China China Merchants Chongqing Road Engineering Inspection Center Co. Ltd Chongqing400067 China Department of Civil and Transportation Engineering Hohai University Nanjing210098 China Key Laboratory for Structure Health Monitoring and Control in Hebei Province Shijiazhuang Tiedao University Shijiazhuang050043 China

Based on data from the meteorological shared data platform, this study proposes a method for predicting the long-term vertical displacement (VD) of concrete bridges by integrating the Northern Goshawk Optimization (NGO) algorithm with the Gated Recurrent Unit (GRU) network. This method can be employed to safely assess concrete bridges and recover missing VD data. Specifically, it uses historical meteorological information and time information provided by the meteorological shared data platform (European Centre for Medium-Range Weather Forecasts) to generate the input parameters of the GRU model. It then employs the long-term VD data from the concrete bridge structural health monitoring system to produce the output parameters of the GRU model. Moreover, the hyperparameters for the GRU model training are optimized using the NGO algorithm. Four NGO-GRU models with different input conditions are proposed, taking the long-term VD prediction of a prestressed concrete bridge as a case study and considering the correlation between different meteorological factors and VD and the long-term time-dependent effects on concrete structures. Through a comparative analysis of the model's prediction performance of multiple sensors under different conditions, it is found that the NGO-GRU model achieved the best prediction performance when using a combination of air temperature, time information, air pressure, solar radiation intensity, and wind speed as inputs, with a prediction error of less than 6.00%. Furthermore, compared with the benchmark models, the NGO-GRU model demonstrated the highest accuracy in VD prediction. Under the optimal input conditions, the prediction performance of the NGO-GRU model improved by 16.46% to 46.17% compared with the other models, validating the robustness and effectiveness of the proposed method. © 2025 Elsevier Ltd

关键词： Concrete bridges Long-term monitoring Meteorological shared data Northern goshawk optimization-based GRU Structural health monitoring Vertical displacement

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Hpp-Based Evaluation of 17 Thermal Conductivity Models for Frozen Soil

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SSRN 2023年

作者： Zheng, Shuang-Fei Wang, Meng Li, Xu Tai, Bo-Wen Li, Guo-Yu Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong University Beijing100044 China Key Laboratory of Structural Health Monitoring and Control Shijiazhuang Tiedao University Hebei province Shijiazhuang050043 China State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and Resources Chinese Academy Sciences Lanzhou730000 China

Thermal conductivity is a key parameter for coupled thermal-hydro-mechanical calculations, significantly influencing the determination of the water and heat migration in frozen soil. However, during the measurement of thermal conductivity for frozen soil, the accuracy can be affected by the interference of ice and water caused by phase transitions with temperature elevation. Consequently, the experimental data on thermal conductivity for frozen soil is insufficient. In this study, the heat-pulse-probe (HPP) method was adopted to conduct measurements of thermal conductivity in silty clay, sand and sand loam, with the temperature perturbation of less than 0.3°C. Additionally, nuclear magnetic resonance (NMR) experiments were implemented to measure the unfrozen water content, enabling further calculation of the ice content. Furthermore, a literature review was conducted to categorize 17 commonly used thermal conductivity calculation models as normalized and hybrid models. The models were evaluated using the λ-θi-θw experimental data, leading to the following conclusions: Among the seven hybrid models, Zhang model shows the best predictive performance and requires no undetermined parameters, making it easy to apply. Sass model is suitable for soils insensitive to deformation of the frozen volume, such as the sand and sand loam studied in this research. Tian model requires the determination of soil-specific parameters, and when the parameters are appropriate, it demonstrates good predictive performance, as observed for the silty clay. Among the 10 normalized models, Joh, Cot, and Luo models are the three with the smallest errors. The establishment of the Ke function needs to consider variations in ice content during phase transitions and changes in the air volume fraction caused by deformation of the frozen volume. These research findings can provide references for future studies on thermal conductivity. © 2023, The Authors. All rights reserved.

关键词： Thermal conductivity

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Evolution Law of Frost-Heaving Pressure of Frozen Circles in Surrounding Rock around Water-Rich Tunnels in Cold Regions

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Zhongguo Gonglu Xuebao/China Journal of Highway and Transport 2022年第9期35卷 340-351页

作者： Zheng, Xin-Yu Xu, Fei Sun, Hao-Kai Gao, Yang Wei, Li-Yuan Geotechnical and Structural Engineering Research Center Shandong University Shandong Jinan250061 China Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China State Key Laboratory for Geomechanics & Deep Underground Engineering China University of Mining and Technology Jiangsu Xuzhou221116 China School of Civil Engineering Southwest Jiaotong University Sichuan Chengdu610031 China

The frost-heaving evolution mechanism of frozen circles in surrounding rock around water-rich tunnel is a key scientific problem that affects the operation safety in cold regions. To explore the evolution law of frost-heaving pressure in frozen circles in such surrounding rock, scaled three-dimensional geomechanical model tests were carried out. In these tests, freezing of a water-bearing surrounding rock at low temperature was considered. The temperature field distribution characteristics of surrounding rock at the tunnel portal section was simulated by introducing ambient air into the tunnel for cooling. Micro-pressure sensors were employed to dynamically monitor the frost-heaving pressure in real time. The spatial and temporal evolution curves of the frost-heaving pressure were obtained for various water content and thickness in surrounding rock. The fitting formulas for parameters such as the frost-heaving rate of surrounding rock, thickness of the frozen circles, and water content were established utilizing multiple regression analysis. Based on this, a theoretical solution for the frost-heaving pressure of the frozen circles in surrounding rock under plain strain state was derived considering the influence of water content and proportion index of surrounding rock. The thermal stress method was used to simulate the evolution characteristics of frost-heaving pressure. Combined with numerical simulations, the test method and theoretical solution were further verified by comparing the predicted frost-heaving pressure with the theoretical and test values. The results indicate that the temperature field of surrounding rock undergoes changes in three stages. This is similar to a regular spoon with a handle-like evolution process;the temperature field of the water-bearing surrounding rock exhibits a non-linear distribution in the descending stage;the temperature field of surrounding rock shows a lagging characteristic relative to the environmental temperature. The sha

关键词： Temperature

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Comprehensive Verification and Analysis of Multi-Scale Remote Sensing Products for Surface Freezing- Thawing Status on the Qinghai-Tibet Plateau

Comprehensive Verification and Analysis of Multi-Scale Remot...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Xiaokang Kou Zhaoyang Jia Shuang Yan Mengjie Jin Yuzhi Zhang Tianliang Wang Key Laboratory of Roads and Railway Engineering Safety Control (Shijiazhuang Tiedao University) Ministry of Education Shijiazhuang Hebei China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang Hebei China Institute of Geographical Sciences Hebei Academy of Sciences Hebei Engineering Research Center for Geographic Information Application Shijiazhuang Hebei China Key Laboratory for Health Monitoring and Control of Large Structures in Hebei Province Shijiazhuang Tiedao University Shijiazhuang Hebei China

ISBN: (数字)9781728163741

ISBN: (纸本)9781728163758

The surface soil freezing and thawing (F/T) status plays important roles in water and energy exchanges, hydrology cycle and terrestrial ecosystem. Passive microwave remote sensing tends to be one of the most effective ways of monitoring global surface F/T status, due to its strong sensitivity to the changes of liquid water and its short revisiting period. Many surface F/T products have been produced based on the observations from different passive microwave sensors. However, due to the differences in spatial scales, satellite data sources, transit times etc., the accuracy and the consistency of different F/T products need to be well considered in front of the comprehensive utilization. In this study, the surface F/T products with resolutions of 36 km, 25 km, 25 km and 6 km derived from SMAP, SSMIS, AMSR-2, AMSR-2 (downscaling) were validated separately based on the in-situ observations in Ngari prefecture and Maqu on the Qinghai-Tibet Plateau. Then a comparison analysis was conducted on the F/T products derived from SMAP and SSMIS to figure out the consistency between F/T products derived from different sensors. The results show that: 1) the verification accuracy in Maqu is higher than that in Ngari prefecture, which reflects the limited capability of passive microwave in identifying the soil surface F/T status in the arid region. 2) The F/T products with resolutions of 6 km and 25 km, which were both derived from AMSR-2 and have the same transit time, showed similar validation accuracies. 3) There is a good agreement between the F/T products derived from SMAP and that from SSMIS. This study will be conducive to the comprehensive application of multi-scale F/T products in the fields of climate change and ecological environment.

关键词： Microwave radiometry Microwave theory and techniques Satellite broadcasting Land surface Spatial resolution Microwave imaging Orbits

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Disease Analysis for 'Single Plate Bearing' in Plate Girder Bridge and Its Strengthening Scheme

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IOP Conference Series: Earth and Environmental Science 2021年第3期719卷

作者： Man Zhao Yiqiang Li School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang Hebei Province China Key Laboratory of Roads and Railway Engineering Safety Control (Shijiazhuang Tiedao University) Ministry of Education Hebei Province China Structure Healthy Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang Hebei Province China

The phenomenon of 'single plate bearing' is one of the diseases in plate girder bridges. In order to study its mechanical characteristics and strengthening schemes, with the help of finite element software ANSYS, 'single plate bearing' of plate girder bridge is simulated numerically in this section. Firstly, models are simulated with beam element, and transversal distribution rule of load is analysed. Then according to the mechanical behavior of plate girder bridge and the reason leading to 'single plate bearing', five strengthening schemes are proposed to delay or avoid 'single plate bearing' and their spatial models are built with solid element Mechanical behaviors such as displacement, stress are contrasted and analysed. Furthermore, transversal stress at hinged joints is analysed in detail, and it is proposed that the adhesive strength between new and old concrete should be applied to test transversal stress at hinged joints. At last according to the merit and demerit of five strengthening schemes, feasible schemes for 'single plate bearing' are given.

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Erratum to: Analytical Solutions of Cracks Emanating from an Elliptic Hole in an Infinite Plate under Tension (Chinese Journal of Mechanical Engineering, (2014), 27, 5, (1057-1063), 10.3901/CJME.2014.0526.300)

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Chinese Journal of Mechanical Engineering (English Edition) 2019年 1-1页

作者： Liu, Shuhong Duan, Shijie Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang050043 China The Key Laboratory for Health Monitoring and Control of Large Structures of Hebei Province Shijiazhuang050043 China Department of Adult Education Shijiazhuang Tiedao University Shijiazhuang050043 China

The original version of this article unfortunately contained a mistake. The presentation of the DOI in printed version was incorrect. The corrected DOI is given below. DOI: 10.3901/CJME.2014.0526.300. © 2014, Chi...

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Effects of the reattachment on dry galloping in the critical Reynolds number range 9

Effects of the reattachment on dry galloping in the critical...

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9th Asia Pacific Conference on Wind Engineering, APCWE 2017

作者： Ma, Wenyong Liu, Qingkuan Liu, Xiaobing Key Laboratory for Health Monitoring and Control of Large Structure Shijiazhuang Tiedao University Hebei province China Department of Wind Science and Engineering Shijiazhuang Tiedao University Shijiazhuang City Hebei Province China

Large amplitude vibrations of circular cylinders in the critical Reynolds number range are reproduced in wind tunnels. Displacements and wind pressure for the cylinders are measured synchronously to reveal the characteristics of aerodynamic force for the vibrating cylinders in a Reynolds number range where flow re-attaches on the rear of the cylinder. Effects of these reattachments on the aerodynamic forces and the vibrations are discussed. The results show that the reattachment can produce unsteady aerodynamic force and excite large amplitude vibration when it forms unstable separation bubble at the early critical Reynolds number range. Once it develops stable separation bubble, the reattachment mitigates the vibrations by creating strong negative aerodynamic damping. © 9th Asia Pacific Conference on Wind Engineering, APCWE 2017. All Rights Reserved.

关键词： Circular cylinders

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