期刊：
Science of The Total Environment,2024年912:169016 ISSN：0048-9697
通讯作者：
Sun, XH
作者机构：
[Sun, Xiaohao; Sun, XH; Wang, Yong] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hung Hom, Kowloon, Hong Kong, Peoples R China.;[Miao, Linchang; Wang, Hengxing] Southeast Univ, Inst Geotech Engn, Nanjing 210096, Jiangsu, Peoples R China.;[Wu, Linyu] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Hubei, Peoples R China.;[Shi, Wenbo] Xuchang Univ, Sch Intelligent Transportat, Xuchang 461000, Peoples R China.;[Kawasaki, Satoru] Hokkaido Univ, Fac Engn, Sapporo, Hokkaido 0608628, Japan.
通讯机构：
[Sun, XH ] H;Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hung Hom, Kowloon, Hong Kong, Peoples R China.
关键词：
EICP;Factors to improve resistance;MICP;Prospective applications;Soil erosion
摘要：
In recent years, the application of microbially induced calcite precipitation (MICP) and enzyme-induced carbonate precipitation (EICP) techniques have been extensively studied to mitigate soil erosion, yielding substantial achievements in this regard. This paper presents a comprehensive review of the recent progress in erosion control by MICP and EICP techniques. To further discuss the effectiveness of erosion mitigation in-depth, the estimation methods and characterization of erosion resistance were initially compiled. Moreover, factors affecting the erosion resistance of MICP/EICP-treated soil were expounded, spanning from soil properties to treatment protocols and environmental conditions. The development of optimization and upscaling in erosion mitigation via MICP/EICP was also included in this review. In addition, this review discussed the limitations and correspondingly proposed prospective applications of erosion control via the MICP/EICP approach. The current review presents up-to-date information on the research activities for improving erosion resistance by MICP/EICP, aiming at providing insights for interdisciplinary researchers and guidance for promoting this method to further applications in erosion mitigation.
摘要：
Numerical seismic wave field simulation is essential for studying the dynamic responses in semi-infinite space, and the absorbing boundary setting is critical for simulation accuracy. This study addresses spherical waves incident from the free boundary by applying dynamic equations and Rayleigh damping. A new multi-directional viscous damping absorbing boundary (MVDB) method is proposed based on regional attenuation. An approximate formula for the damping value is established, which can achieve absorbing the boundary setting by only solving the mass damping coefficients without increasing the absorbing region grid cells or depending on the spatial and temporal walking distance. The validity and stability of the proposed method are proven through numerical calculations with seismic sources incident from different angles. Meanwhile, the key parameters affecting the absorption of the MVDB are analyzed, and the best implementation scheme is provided. In order to meet the requirements of mediums with different elastic parameters for boundary absorption and ensure the high efficiency of numerical calculations, the damping amplitude control coefficients k can be set between 1.02 and 1.12, the thickness of the absorbing region L is set to 2-3 times of the wavelength of the incident transverse wave, and the thickness of the single absorbing layer is set to the size of the discrete mesh of the model Delta l.
摘要：
Polyaniline (PANI) particles were synthesized using aniline (AN), dodecyl benzene sulfonic acid (DBSA), and ammonium persulfate (APS). The particles were analyzed using scanning electron microscope (SEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). A PANI/waterborne polyurethane composite material (PANI-WPU) was obtained by combining it with polyethylene glycol (PEG600), diphenylmethane diisocyanate (MDI), dimethylol propionic acid (DMPA), N-methyl pyrrolidone (NMP), and dibutyltin lauric acid (DBTDL). The structure was characterized by the FTIR spectrum. The mechanical characteristics of the coating film were evaluated with respect to the PANI content, as well as its water absorption, glossiness, electrochemical corrosion resistance, and acid and alkali resistance. The PANI/waterborne polyurethane film has a maximum tensile strength of 23 +/- 1$$ \pm 1 $$ MPa, an elongation of 1012%, a pencil hardness of 5H, a flexibility of 2 mm, an impact resistance of 50 cm, the water absorption of 14.66%, and the glossiness of 99.9 +/- 0.1$$ \pm 0.1 $$ at 60 degrees. When the PANI content is 0.7%, the mechanical characteristics, glossiness, and anti-corrosion performance of the composite film improve. The corrosion inhibition efficiency of the aqueous polyurethane coating film with PANI can reach 99.74%, as shown by the examination of electrochemical polarization curves and impedance spectra. The tinplate is coated with a 0.7% PANI-WPU composite material and edge sealing. This coating provides excellent protection against acid and alkali resistance, as demonstrated by its ability to withstand immersion in 10% H2SO4 and 10% NaOH solution for 90 days without any paint peeling off.
摘要：
Bolted connections have become the most widely used connection method in steel structures. Over the long-term service of the bolts, loosening damage and other defects will inevitably occur due to various factors. To ensure the stability of bolted connections, an efficient and precise method for identifying loosened bolts in a given structure is proposed based on computer vision technology. The main idea of this method is to combine deep learning with image processing techniques to recognize and label the loosening angle from bolt connection images. A rectangular steel plate was taken as the test research object, and three grade 4.8 ordinary bolts were selected for study. The analysis was conducted under two conditions: manual loosening and simulated loosening. The results showed that the method proposed in this article could accurately locate the position of the bolts and identify the loosening angle, with an error value of about +/- 0.1 degrees, which proves the accuracy and feasibility of this method, meeting the needs of structural health monitoring.
作者机构：
[Wu, Jie; Song, Liang; Dong, Yiqie; Zhang, Rongtang] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Li, Jun; Li, J] Shandong Hydroenvironm Geol Engn Co Ltd, Jinan 250013, Peoples R China.;[Qin, Shipeng] Jinan Rail Transit Grp Construct Investment Co Ltd, Jinan 250101, Peoples R China.
通讯机构：
[Li, J ] S;Shandong Hydroenvironm Geol Engn Co Ltd, Jinan 250013, Peoples R China.
关键词：
modified model;deep bed filtration effect;permeation diffusion
摘要：
The study of the slurry reinforcement mechanism is mainly focused on the interaction between slurry and soil. The seepage effect of the slurry always exists no matter what way the slurry interacts with the soil around the pile. In the process of slurry diffusion, the porosity of the soil, the permeability of the slurry, and the slurry pressure vary due to some cement particles being blocked by the soil particle skeleton. Therefore, the study of the slurry filtration effect is of great significance for predicting the permeation and diffusion law of slurry. In this paper, a macroscopic linear filtration model was introduced and the changes of slurry properties in the permeation diffusion process were considered. Firstly, a spherical (cylindrical) permeation diffusion model, which takes the linear filtration effect and the variation of slurry viscosity into account, was derived based on the conservation of mass. Furthermore, in order to more accurately reflect the influence of the filtration effect on the slurry permeation diffusion model, a polynomial nonlinear filtration model was proposed, and the numerical solution for the permeation diffusion model was derived using finite difference and finite element methods. Finally, the numerically simulated values, the measured values, and the values from the spherical permeation diffusion model that does not consider slurry viscosity variations were compared. The results indicate that the grout pressure is inconsistent with the measured value without considering the effect of the filtration. The initial grouting pressure calculated by the model in this paper is slightly larger, and the required grouting pressure over time is greater than that without considering the filtration effect, regardless of whether the grout diffuses in a spherical or cylindrical manner. The results of this study can contribute to a better understanding of grouting engineering and provide some theoretical guidance for actual grouting.
期刊：
International Journal of Geomechanics,2023年23(3):06023002 ISSN：1532-3641
通讯作者：
Juehao Huang
作者机构：
[Huang, Juehao] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Huang, Juehao; Yan, Xiaoling; Chen, Jian] Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China.;[Chen, Jian; Fu, Xiaodong] Inst Rock & Soil Mech, Chinese Acad Sci, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Chen, Jian] Inst Rock & Soil Mech, Chinese Acad Sci, Hubei Key Lab Geoenvironm Engn, Wuhan 430071, Peoples R China.;[Chen, Jian] Ningbo Univ Technol, Soft Soil Res Ctr, State Key Lab Geomech & Geotech Engn, Ningbo 315211, Peoples R China.
通讯机构：
[Juehao Huang] A;Assistant Professor, State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China;Assistant Professor, School of Engineering Science, Univ. of Chinese Academy of Sciences, Beijing 100049, China
摘要：
The mechanical behaviors of subgrade soils will change after cyclic loading, resulting in a modification of foundation bearing capacity and the development of additional settlement. Recognizing this, cyclic triaxial tests were conducted to remolded laterite clay, and reconsolidation was allowed. During the process, the cyclic loading was applied under undrained and partially drained conditions, respectively. Results show that the variations of both postcyclic undrained strength and elastic modulus versus degree of reconsolidation are different: the postcyclic elastic modulus increases with an increase of the degree of reconsolidation, while the undrained strength decreases a little under the condition of the large degree of reconsolidation. Furthermore, there are specific degrees of reconsolidation, making the postcyclic undrained strength and elastic modulus equal to the corresponding test results of the specimen without reconsolidation. Moreover, the greater the number of cycles, the larger the elastic modulus of the specimens with full reconsolidation, and the lower the elastic modulus of the specimens without reconsolidation. The undrained strengths of the specimens with full reconsolidation are all higher than those of the specimens without cyclic loading, whereas those of the specimens without reconsolidation are all lower. In addition, both postcyclic undrained strength and elastic modulus between cyclic loading under undrained and partially drained conditions are compared: the elastic moduli of the specimens under partially drained conditions are greater than those obtained under undrained conditions, while the undrained strengths obtained under partially drained conditions are equal to that under undrained conditions at a certain number of cycles.
期刊：
Environmental Science and Pollution Research,2023年30(13):39076-39092 ISSN：0944-1344
通讯作者：
Chao Zou
作者机构：
[Zou, Chao; Hu, Zihao] Guangdong Univ Technol, Sch Civil & Transportat Engn, Guangzhou 510006, Peoples R China.;[Tian, Li] Guangzhou Metro Design & Res Inst Co Ltd, Guangzhou 510000, Peoples R China.;[Wu, Jie] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430000, Peoples R China.
通讯机构：
[Zou, Chao] S;School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, 510006, China. chao.
关键词：
Train-induced vibration;Vibration prediction;Attenuation;Vibration transmission;Metro depot;Over-track building
摘要：
The investigation of the influence of soil-structure coupling on the vibration propagation pattern is the key to ensuring the reliability of the prediction of train-induced building vibration. This study selects different metro depots with over-track buildings as the research objects based on the existing engineering examples. It analyzes the general laws of vibration propagation from the ground soil to the building columns. The study provides valuable references for predicting vibration and designing vibration isolation measures for over-track buildings. Additionally, this study proposes a vibration prediction method for over-track buildings above metro depots based on the back propagation (BP) neural network model in machine learning. This model considers the soil-structure coupling loss in a data-driven manner based on the rich data samples, which avoids the problems of complex numerical simulation calculations and parameter uncertainties to some extent. This prediction method has a good balance of efficiency and convenience and also meets the accuracy requirements. It was judged to be a promising prediction method for the preliminary design stage of the over-track buildings above metro depots.
摘要：
Widespread interest has been drawn to the use of solid waste fillers as a partial replacement for natural fillers in high-performance asphalt mixtures in recent years. However, variations in the material properties of solid waste fillers remain a problem for the recycling method. To address this issue, the limestone powder in asphalt mixtures was replaced with three solid waste fillers, including steel slag powder, tailings powder and calcium carbide slag powder in this study. The chemical composition of the fillers was first characterized to assess the homogeneity of the material. Then, a dense-graded asphalt mixture (AC) and a stone matrix asphalt (SMA) mixture were designed, produced and characterized for wet stability. The results show that the asphalt mixtures with solid waste fillers were superior to limestone powder (LP) asphalt mixtures in terms of resistance to water damage, and the steel slag powder showed the best improvement in moisture stability of the asphalt mixtures. The optimum substitution of solid waste filler for limestone filler was 25%. With the addition of anti-stripping agents, the moisture stability of the asphalt mixture with limestone filler was also greatly enhanced. On the contrary, a marginal enhancement was observed in the moisture stability of asphalt mixtures using solid waste fillers. Solid waste fillers can be used in asphalt mixtures and have a similar function as that of anti-stripping agents. In summary, the use of solid waste fillers to replace mineral fillers in asphalt mixtures is a reliable, value-added recycling option.
通讯机构：
[Geng, X ] W;Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430048, Peoples R China.
关键词：
low cycle fatigue;crack growth;cracked plate;experimental study
摘要：
The traditional study on fatigue strength for ship structures usually focuses on high cycle fatigue and ignores low cycle fatigue. However, given the recent trend towards large-scale ship development, the stress and deformation experienced by ship structures are becoming increasingly significant, leading to greater attention being paid to low cycle fatigue damage. Therefore, experimental and numerical studies on crack propagation behavior of cracked plates under low cycle fatigue loads were carried out in this paper, in order to explain the fatigue crack propagation mechanism. The effect of the stress ratio and maximum applied load on the crack propagation behavior was investigated by conducting experimental research on the cracked plate of AH32 steel. The experimental results show that an increasing maximum applied load and decreasing stress ratio will shorten the fatigue life of the cracked plate. Meanwhile, based on the finite element method, the distribution of the stress–strain field at the crack tip and the effect of crack closure were evaluated. The influencing factors such as the stress ratio and crack length were considered in numerical studies, which provided a new way to study the low cycle fatigue crack propagation behavior.
期刊：
Case Studies in Construction Materials,2023年18:e01794 ISSN：2214-5095
通讯作者：
Lu, Haijun(luhaijun111@163.com)
作者机构：
[Liu, Mengyi; Lu, Haijun; Wang, Chaofeng; Liu, Yajun] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Liu, Mengyi; Lu, Haijun; Liu, Yajun] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.
通讯机构：
[Haijun Lu] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan 430023, China<&wdkj&>State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
关键词：
Modified municipal sludge;Liner materials;Landfill leachate;Service performances;Microstructure characteristics
期刊：
International Journal of Geomechanics,2023年23(4):06023003 ISSN：1532-3641
通讯作者：
Huang, JH
作者机构：
[Huang, Juehao; Chen, Jian; Fu, Xiaodong; Zhang, Zhenping] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Huang, Juehao; Chen, Jian; Fu, Xiaodong] Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China.;[Chen, Jian] Chinese Acad Sci, Inst Rock & Soil Mech, Hubei Key Lab Geoenvironm Engn, Wuhan 430071, Peoples R China.;[Chen, Jian] Ningbo Univ Technol, Soft Soil Res Ctr, State Key Lab Geomech & Geotech Engn, Ningbo 315211, Peoples R China.;[Yu, Song] China Railway Major Bridge Reconnaissance & Design, Wuhan 430050, Peoples R China.
通讯机构：
[Huang, JH ] C;Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China.
关键词：
Postcyclic stiffness characteristics;Laterite clay;Cyclic confining pressure;Degree of reconsolidation
摘要：
The changes in mechanical behaviors of soils after cyclic loading will lead to the generation of additional settlements. The postcyclic stiffness characteristics of soils are usually analyzed by using conventional cyclic triaxial tests, in which only cyclic deviator stress is applied under undrained conditions; however, the cyclic variations of both axial stress and horizontal stress under traffic loading were observed. Moreover, the pore water was permitted to drain under cyclic loading. Therefore, cyclic triaxial tests under partially drained conditions were performed to investigate the postcyclic stiffness characteristics of remolded laterite clay. The influences of variables, such as the cyclic deviator stress, number of cycles, cyclic confining pressure, and degree of reconsolidation, were evaluated. The postcyclic elastic modulus increases as the cyclic deviator stress, number of cycles, and degree of reconsolidation increase, while it decreases as the cyclic confining pressure increases. Nevertheless, the ratio of the postcyclic elastic modulus with and without cyclic confining pressure decreases as the cyclic confining pressure increases; the postcyclic elastic modulus ratio of the degree of reconsolidation to without reconsolidation increases linearly with the increasing degree of reconsolidation. Based on the result, an empirical formula for the postcyclic elastic modulus, considering the effects of both cyclic confining pressure and the degree of reconsolidation, was proposed. The predicted results match the measured data well, indicating that the formula is valid for the prediction of the postcyclic elastic modulus of laterite clays after cyclic loading.
作者机构：
[Tan, Li; Li, Mengna] Wuhan Polytech Univ, Key Res Inst Humanities & Social Sci Hubei Prov, Food Safety Res Ctr, Wuhan 430048, Peoples R China.;[Huang, Meng; Cheng, Congxi; Hu, Canwei; Tan, Li; Li, Mengna; Luo, Wei; Zhou, Xiao] Wuhan Polytech Univ, Sch Management, Wuhan 430048, Peoples R China.;[Yang, Bin] China Univ Min & Technol, Sch Publ Policy & Management, Xuzhou 221008, Peoples R China.;[Shuai, Shuang] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.
通讯机构：
[Mengna Li] F;Food Safety Research Center, Wuhan Polytechnic University, Key Research Institute of Humanities and Social Sciences of Hubei Province, Wuhan 430048, China<&wdkj&>School of Management, Wuhan Polytechnic University, Wuhan 430048, China
关键词：
Landscape ecological risk;Land use transformation;Influencing factors;Core water source area
关键词：
autonomous vehicles;last-mile transport;preference heterogeneity;theory of planned behavior;latent class logit model
摘要：
The "last-mile problem" of public transportation is one of the main obstacles affecting travelers who choose to utilize public transport. Although autonomous vehicles (AVs) have made much progress, they have not been officially put into commercial use. This paper adopts stated preference experiments to explore the impact of shared AVs on the last-mile travel behavior of metro users and takes Wuhan as an example for case analysis. First of all, this paper establishes a structural equation model (SEM) based on the theory of planned behavior to explore latent psychological variables, including travelers' attitudes (ATTs), subjective norms (SNs), perceived behavior control (PBC), and behavioral intention of use (BIU) toward AVs. These latent psychological variables are incorporated into the latent class (LC) logit model to establish a hybrid model with which to study the factors and degree of influence on the travel mode choices of travelers for the last mile of their metro trips. The results show that travelers have preference heterogeneity for the travel mode choices for the last mile of metro trips. Through the analysis of LCs, education, career, and income significantly impact the classification of LCs. The latent psychological variables towards AVs have a significant impact on the travel behavior of respondents, but the impacts vary among different segments. Elastic analysis results illustrate that a 1% increase in the travel cost for shared AVs in segment 1 leads to a 7.598% decrease in the choice probability of using a shared AV. Respondents from different segments vary significantly in their willingness to pay for their usage, and the value of travel time for high-income groups is relatively higher.
通讯机构：
[Zhu, SY ] W;[Xing, ML ] C;Wuhan Polytech Univ, Sch Civil Engn & Architecture, 68 Xuefu South Rd, Wuhan 430023, Hubei, Peoples R China.;Changan Univ, Xian Key Lab Modern Transportat Funct Mat, 65 Changan Middle Rd, Xian 710061, Peoples R China.
关键词：
WM OUFC-5;Life cycle assessment;Energy consumption;Carbon emissions;Green maintenance material
摘要：
The warm mix (WM) 4.75 mm nominal maximum aggregate size (NMAS) Open-Graded Ultra-thin Friction Course (WM OUFC-5) represents an innovative green preventive maintenance material boasting commendable road performance. Its potential to address carbon peak and neutrality goals objectives has garnered significant interest. This study aims to quantify the energy-saving and carbon reduction benefits of WM OUFC-5. Three commonly used preventive maintenance materials, including thin overlay (TO), synchronous surface dressing (SSD), and micro-surfacing (MS) in Hubei province, China, were selected as a control group. Employing the process-based life cycle assessment (PLCA), an evaluation framework and computational model was devised to gauge the energy and carbon footprints of each maintenance material. A comparative analysis was then conducted to identify the primary energy and emission contributors of WM OUFC-5 across different life-cycle phases. The results indicate that WM OUFC-5 is a highly sustainable material with low energy consumption and carbon emissions, with its energy consumption being merely 47.2% of TO and 50.7% of MS. And its carbon emissions are 64.3% lower than TO, 26.9% lower than MS, and 49.8% lower than SSD. Throughout the maintenance life cycle, the raw materials production and processing phase and the mixture production phase emerged as the predominant contributors to energy consumption and carbon emissions. The study also provided actionable recommendations to curtail energy and carbon footprints across all phases of the asphalt pavement maintenance life cycle. This study provides support for the low-carbon development of asphalt pavement maintenance in China.
摘要：
Hydrated salts phase change materials (PCMs) have a great potential for use in floor radiant heating considering outstanding cost competitiveness and remarkable energy storage density. However, their inappropriate phase change temperatures and the limited methods for temperature adjustment have hindered their widespread applications. Herein, using the formation of noneutectic mixture to realize phase change temperature adjustment, a novel composite PCM used in the floor radiant heating was developed based on sodium acetate trihydrate (SAT) as main PCM, glycine as temperature modifier and Na2HPO4.12H2O as nucleating agent. The temperature regulation mechanism was discussed and properties of the composite PCM were investigated. The results showed that glycine could regulate melting temperature of SAT from 48.34 to 58.38 degrees C, ascribing to the formation of hydrogen bond between them. Thereinto, the mixture containing 12% glycine melted at 48.62 degrees C with enthalpy of 258.5 J g-1, making it applicable to the floor radiant heating. With the addition of 0.5% Na2HPO4.12H2O, the crystallization behavior of the composite PCM was promoted with a low supercooling degree (3.62 degrees C). The composite PCM presented a melting temperature of 47.55 degrees C with enthalpy of 256.5 J g-1, good thermal stability and reliability, indicating that the material can be promisingly engineered into the floor radiant heating.
摘要：
A 1 at% carbon non-equiatomic doped Co19Cr5Fe38Ni19Mn19 high-entropy alloy was synthesized by vacuum arc-melting in a high-purity argon atmosphere, followed by homogenization, cold rolling, and annealing under various conditions. The evolutions of microstructure and mechanical properties during annealing were systematically studied and compared with the carbon free alloy. Results showed that nano-sized fibrous deformation grains were formed in the 90% cold rolled alloys, resulting in high strength but low plasticity. Recovery sub-structures and recrystallized grains gradually formed with increasing annealing temperature, leading to a significant decrease in defect density, thereby softening the materials and increasing their plasticity. The early stage of recovery was mainly related to the migration of vacancy and interstitial carbon atoms, while dislocation climb became the main recovery mechanism in the late recovery stage. The carbon-doped alloy exhibited a higher recovery activation energy compared with the carbon free alloy. Therefore, 1 at% interstitial carbon effectively increased the recovery and recrystallization resistance of the Co19Cr5Fe38Ni19Mn19 alloy.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
摘要：
Blockage of leachate drainage facilities is a common engineering problem in landfill operation. The key factors that cause blockage of drainage facilities in landfill leachate are the deposition of suspended solids (SS) with colloids and the precipitation of inorganic salts. To determine the combined sedimentation law of SS, colloids and inorganic salts, a combined sedimentation test of suspended solids, colloids and inorganic salts was conducted. To further clarify the resulting clogging characteristics of the water-conducting sand layers, a sand column blocking test were conducted, and mineral composition and grain characteristics of sediments were determined. The experimental results shown that the colloids (silver iodide) and inorganic salts (calcium chloride or aluminum sulfate) increased the sedimentation rate of SS by 8 to18 times. Among them, the effect of AgI colloid was the most significant, followed by effect of calcium chloride, while effect of aluminum sulfate was the weakest. Compared with sand column clogging caused by SS, this combined migration shortened the sand column clogging time by more than half and reduced hydraulic conductivity by nearly two to three orders of magnitude. This study contributes to the accurate assessment of the service performance of landfill leachate drainage systems.
通讯机构：
[Xiantao Qin; Rong Luo] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, 68 Xuefu South Road, Wuhan, Hubei, 430023, China<&wdkj&>School of Transportation and Logistics Engineering, Wuhan University of Technology, 1178 Heping Avenue, Wuhan, Hubei, 430063, China
关键词：
Phosphogypsum;Resource utilization;Pretreatment method;Retarder;Cementitious materials;Filler and modifier
摘要：
Phosphogypsum (PG), as a by-product of phosphoric acid and a bulk industrial solid waste, has increased sharply due to the development of the phosphorus chemical industry. Because of the increasing serious environmental problems caused by stockpiling of PG, an analysis of its utilization status and development trend in civil engi-neering is important to improve the PG utilization rate. In this review, the chemical compositions of different PG and pretreatment methods were compared and analyzed firstly. And then, the utilization of PG including cement retarder, building materials, cement raw materials, concrete raw materials, cementitious materials, and fillers and modifiers were summarized. Current review concluded that calcination as a pretreatment method has special advantages, and future work should aim to propose advanced calcination incorporating with the addition of effective admixtures, reduction of calcining temperature, and activation of inert minerals. Moreover, studies have confirmed the feasibility of adopting PG as a retarder, cementitious materials, filler and modifier. Future research is recommended to focus on improving the reactivity and long-term stability. Meanwhile, some new PG -based materials are proposed to promote the large-scale, environment-friendly and resourceful utilization of PG.
摘要：
The austenitic strain-induced precipitation behavior of Ti-V-Mo complex microalloyed steel was investigated by using the stress relaxation method. The changes in precipitation phase, microstructure and hardness of the Ti-V-Mo complex microalloyed steel with varying relaxation temperatures were studied by using an optical microscope, a transmission electron microscope and a Vickers hardness tester. The results revealed that the precipitation-time-temperature diagram of Ti-V-Mo complex microalloyed steel exhibited a characteristic "C" shape, with the nose point temperature being close to 1000 degrees C, and the corresponding precipitation start and end times were 4.1 and 472.4 s. The strain-induced precipitation phase is identified as (Ti, V, Mo)C particles and nucleates primarily at dislocations and subgrain boundaries. With the temperature rising from 950 to 1050 degrees C, the average size of precipitation increased from 10.8 to 33.7 nm. Appropriately lowering the austenite strain temperature can refine the austenite precipitation phase, which is conducive to the (Ti, V, Mo)C from ferrite, thus improving the precipitation strengthening effect. Furthermore, the average grain size of prior austenite increased from 60 to 70 mu m with temperature increasing from 920 to 1080 degrees C under holding 2000 s, and the high-density (Ti, V, Mo)C particles of the strain-induced precipitation played a crucial role in preventing significant coarsening of prior austenite grains. The austenitic deformation temperature has almost no effect on the hardness of experimental steels.
通讯机构：
[Haijun Lu; Yong Wan] A;Authors to whom correspondence should be addressed.<&wdkj&>State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan 430023, China<&wdkj&>State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
关键词：
modified sludge;industrial waste;powdered construction waste;mechanical strength;microstructure
摘要：
Each year, China produces a substantial amount of municipal sludge, industrial waste (slag, fly ash, and desulfurized gypsum), and construction waste, while its recycling rate is low. If not disposed in a properly and timely manner, this inequity can have serious environmental impacts. This study aimed to prepare a new type of modified sludge material with high strength, low shrinkage, and low permeability by curing municipal sludge with industrial waste (slag, desulfurized gypsum, and fly ash) and powdered construction waste. At specific maintenance ages, the modified sludge material was examined for shrinkage deformation, water content, compressive strength, and hydraulic conductivity. The modified sludge material was also tested by scanning electron microscopy (SEM + EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) tests. The hydration products, micromorphology, and elemental composition of modified sludge were also analyzed at specific maintenance ages. These analyses revealed the mechanism of solidification of municipal sludge by industrial waste and powdered construction waste and the changes in the microstructure of the sludge. The results showed that the compressive strength of the modified sludge ranged from 3.83 to 8.63 MPa, volumetric shrinkage ranged from 2.12 to 12.68%, and hydraulic conductivity ranged from 1.65 x 10(-8) to 2.21 x 10(-7) cm/s after 28 d of maintenance. The active substances, such as SiO2, Al2O3, and CaO, in the industrial waste, powdered construction waste, and municipal sludge were subjected to a hydration reaction in an alkaline environment to produce dense blocks, agglomerates of C-S-H, ettringite, gismondine, and other hydration products. The compressive strength of the modified sludge increased, and its internal structure was dense.
