摘要：
To investigate crack propagation and the coalescence mechanism of a rock bridge under unloading condition induced by intensive excavation of rock mass, the direct shear test with unloading normal stress and corresponding particle flow code (PFC) simulation were conducted on the sandstone specimen containing a parallel fissure pair considering different fissure inclinations (varied from 0 degrees to 90 degrees) and initial shear stresses (varied from 4 to 7 MPa). Three failure patterns (i.e., shear failure, tensile failure, and tensile-shear mixed failure) are identified as experimental and numerical results. The failure pattern transforms in the order of a shear, tensile, and tensile-shear mixed failure pattern as the fissure inclination increases. Three displacement field types are summarized and correspond to different failure patterns. Comparing the shear strength, cracking process, and microscopic displacement field in the direct shear test with unloading normal stress and the conventional direct shear test, normal unloading weakens the shear strength of the specimen under the selected stress conditions (initial normal stress is 20 MPa, initial shear stress ranges from 4 to 7 MPa). Rebound deformation in the process of unloading promotes the high proportion of tensile cracks for the tested fissure inclinations.
摘要：
In the practical operation of traditional landfills, compaction clay often experiences cracking, while the HDPE geomembrane may tear and bulge, resulting in a compromised performance of the landfill covering system. To address this issue, a capillary retarding covering material for landfill sites is proposed by utilizing municipal sludge and construction waste particles as substrates and incorporating a small quantity of calcium bentonite. The mechanical characteristics of the covering material were investigated using a standard consolidation test and a triaxial compression test. A permeability test and a soil water characteristic curve (SWCC) test were conducted to examine the permeability and capillary retarding effect of the covering material. Microscopic tests including SEM scanning, laser particle size analysis, and T2 NMR analysis were performed to investigate the connection mode, particle size composition, and pore structure characteristics of the covered particles. Based on the aforementioned research, the following conclusions can be drawn: The cohesion of the covering material ranged from 50 to 150 kPa, while the internal friction angle ranged from 24.23 degrees to 31 degrees. The cohesion was directly proportional to the content of construction waste, whereas the internal friction angle was inversely proportional to calcium bentonite content. The permeability coefficient ranged from 5.04 x 10-6 cm/s to 7.34 x 10-5 cm/s, indicating a certain level of impermeability. Both the sludge and the calcium bentonite contents jointly influenced the final permeability coefficient in a negative correlation manner, with a notable hydraulic hysteresis phenomenon observed. A higher content of construction waste leads to a more pronounced supporting force exerted by the formed skeleton structures within a load pressure range between 0 and 1600 kPa. When considering a mass ratio of municipal sludge: construction waste: calcium bentonite as 30:60:7, respectively, only a decrease in the pore ratio by approximately 13.20% was observed. This study provides valuable data support for designing and applying capillary retarding cover barrier systems in landfills.
摘要：
This study proposed a new curing agent consisting of slag and desulfurization gypsum industrial waste to solidify Cr(VI)-contaminated soils and prevent its migration and bioaccumulation in the ecosphere. The curing agent dosage of 10-30% resulted in a Cr(VI) toxic leaching concentration, compressive strength, and hydraulic conductivity range of 0.118-5.824 mg/L, 2.70-10.22 MPa, and 1.70 x 10-9-1.37 x 10-6 cm/s, respectively. Following four dry and wet cycles, the dosage of the curing agent was found to be 20-30% to achieve minimum environmental safety requirements. Cr(VI) in the cured specimens mainly existed as CrO42-, or acid salt, in which a portion was changed to Cr(III) during precipitation or directly was encased in the silica-alumina mesh structure. The adsorption capacity of hexavalent chrome on the outer of the hydration product groups was insignificant owing to the electronegativity. Hence, the Cr(VI) was solidified by hydrides such as C-S(A)-H and calcium alumina inclusions. Calcite, quartz, and several zeolite-like substances were also found to be colloidal in the pores to block Cr(VI).
期刊：
Journal of Hazardous Materials,2024年465:133198 ISSN：0304-3894
通讯作者：
Lan, JR
作者机构：
[Pan, Cong; Lan, Jirong; Hou, Haobo] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China.;[Lan, Jirong; Sun, Yan; Kai, Ming-Feng] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.;[Dong, Yiqie] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.
通讯机构：
[Lan, JR ] W;Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China.
关键词：
Amorphous structure;CSWR/PMS system;Carbamazepine;Copper tailing;High value application
摘要：
It is a green and sustainable path to establish cheap solid waste-based catalyst to establish peroxymonosulfate (PMS) catalytic system for the degradation of carbamazepine (CBZ) in water. In this study, durable copper tailing waste residue-based catalyst (CSWR) was prepared, and efficient CSWR/PMS system was constructed for catalytic degradation of CBZ for first time. The morphology and structure of CSWR changed from clumps to porous and loose amorphous by alkali leaching and medium temperature calcination. The reconstructed surface of the CSWR exposes more active sites promotes the catalytic reaction and increases the degradation rate of CBZ by more than 39.8 times. And the CSWR/PMS achieved a CBZ removal of nearly 99.99 % in 20min. In particular, perovskite-type iron-calcium compounds were formed, which stimulated the production of more HO(•) and SO(4)(•-) in the system. DFT calculation shows that CSWR has stronger adsorption energy and electron transfer ability to PMS molecules, which improved the degradation efficiency of the system. In general, this study proposed a means of high-value waste utilization, which provided a new idea for the preparation of solid waste based environmental functional materials and is expected to be widely used in practical wastewater treatment.
摘要：
A green and sustainable approach was employed to synthesize N, O-codoped porous carbon nanorods with two-end-open characteristics. In this method, a crab shell was utilized as a template and activator, while egg white served as a carbon precursor. The resulting carbon nanorods sintered at 700 degrees C (CNRs-700), exhibited cross-linked pore channels, a high surface area, and abundant defects and active sites. These features imparted superior energy storage properties to the material, enabling its application as both an anode for lithium-ion batteries and a supercapacitor. The CNRs-700 demonstrated an exceptional lithium storage capacity of 530.6 mAh g(-1) at 2 A g(-1), corresponding to 90.1% of the capacity achieved at 100 mA g(-1), which is ascribed to the pseudocapacitive contribution. Furthermore, in an evaluation combining a three-electrode configuration in KOH electrolyte at a high current density of 50 A g(-1), the CNRs-700 retained a specific capacitance of 140 F g(-1). For symmetrical supercapacitors based on CNRs-700 in 1 M Na2SO4 electrolyte, the energy density reached 27.1 Wh kg(-1) at a 375 W kg(-1) power density, demonstrating remarkable cyclability over 10,000 consecutive cycles. The superior rate performance and cycling stability would accentuate the suitability of the biomass-derived carbon materials for such systems.
通讯机构：
[Huang, D ] C;Changan Univ, Coll Geol Engn & Geomat, Xian 710054, Peoples R China.
关键词：
Discontinuity;Shear behavior;Failure pattern;Unloading normal stress;Shear strength criteria
摘要：
The shear mechanical behavior of discontinuities under unloading conditions induced by intensive rock mass excavation differs from that under loading conditions. Therefore, the mechanical parameters obtained from the conventional direct shear test cannot effectively be used to assess the stability of excavated rock masses. To solve this problem, we conducted a series of experiments on saw-toothed discontinuities with different undulating angles and initial shear stresses under unloading normal stress with constant shear stress. The test results showed that the shear pattern transformed from climbing to climbing-gnawing and then to gnawing patterns as the undulating angle and initial shear stress increased. The shear stress remained stable with increasing shear displacement after instability in the climbing pattern, decreased with fluctuations in the climbing-gnawing pattern, and dropped steeply in the gnawing pattern. A negative linear correlation exists between the unloading magnitude and the initial shear stress. Unloading normal stress promoted deformation rebound and sawtooth damage, reducing the mobilizing shear strength. Modified Patton and Barton shear strength criteria considering the undulating angle, initial stress, and failure pattern under unloading normal stress were proposed. The shear mechanical behavior of saw-toothed discontinuities with different undulating angles and initial shear stresses under unloading normal stress with constant shear stress are investigated.The failure pattern changes from the climbing pattern to the climbing-gnawing pattern and then to the gnawing pattern as the undulating angle and the initial shear stress increase.Unloading promotes the increase in rebound deformation and the area of the damage zone, leading to the decrease in shear strength of saw-toothed discontinuities.The modified Patton criterion and the Barton criterion are proposed for unloading normal stress considering the undulating angle, initial stress state, and failure pattern.
摘要：
Wet sewage sludge (WSS) self-moisture gasification is a promising route for H2-rich syngas production. This research investigated the co-gasification of WSS and corn stalks (CS), focusing on the effects of self-moisture content. Thermogravimetric analysis of the pyrolysis of the mixture (WSS:CS = 40:60 wt%) revealed that the reactions followed a three-parallel-reaction model. The co-gasification process was performed to compare the effects of self-moisture and external steam used as gasification agents, respectively. The results showed that the self-moisture gasification led to higher H2 yields (0.057–0.11 L/g), gas yields (0.19–0.21 L/g), and specific gas energy (2.62–2.72 MJ/kg) than those in external steam gasification (0.055–0.090 L/g, 0.16–0.18 L/g and 2.32–2.52 MJ/kg, respectively). Additionally, self-moisture gasification also resulted in lighter tar with primarily light organic acids (28.0%), and char with weaker aromatic structure features, attributed to longer reaction time during diffusion of pyrolysis products. Overall, this study provided theoretical foundations for the high-value exploitation of WSS.
期刊：
Construction and Building Materials,2024年411:134273 ISSN：0950-0618
通讯作者：
Zheng, ZS;Huang, YJ
作者机构：
[Zeng, Chen] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Liu, Gang; Wang, Xiang; Zheng, ZS; Zheng, Zhi-shan] Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;[Zhang, Hui; Huang, Yu-jie] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
通讯机构：
[Zheng, ZS ] W;[Huang, YJ ] N;Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
关键词：
Non-uniform corrosion of steel;3D mesoscale model;Mass transfer;Electrochemical corrosion;Bi-directional erosion
摘要：
Chloride-induced corrosion of steel in reinforced concrete (RC) exhibits complicated mechanisms such as chlo-ride diffusion, oxygen diffusion, electrochemical polarization, dissolution and deposition of steel. This work investigates the 3D non-uniform corrosion behavior of steel in RC by integrating all the possible mechanisms and mesoscale heterogeneities, for the first time. The anodic Tafel slope is used to describe the depassivation of steel induced by chloride, while the dynamic process of oxygen supply and consumption is considered as well as the inhibition of the cathodic reaction caused by oxygen concentration. The coupling of mass transfer and electro-chemical corrosion in RC is developed and validated. Mesoscale RC models with realistic aggregate, mortar, steel and interface are generated through a physically-based approach similar to casting procedures. The simulation results show that the 3D mesoscale RC model can simultaneously capture the non-uniform corrosion patterns of steel along the circumferential and longitudinal directions, offering significant application value in accurately predicting steel corrosion morphology. The random distribution of aggregates affects the local non-uniform corrosion of steel, but has little influence on the overall cumulative corrosion level. The local non-uniform corrosion of steel gradually weakens with the increase in chloride erosion time. The non-uniform corrosion of side steel is enhanced with the increase of the steel diameter and the decrease of the protective layer thickness. Bi-directional erosion mainly enhances the uniform corrosion of corner steel.
摘要：
Elemental doping has been widely employed to manipulate the electrical and thermal transport properties of thermoelectric materials, without considering the influence to mechanical properties. In skutterudites, electronegative S-dopants have been found to reduce the lattice thermal conductivity. However, the effect of the covalent S-Sb bond on the mechanical properties of CoSb3 skutterudites remains unexplored. Compressive strength, in particular, exhibits a significant reduction in S-doped skutterudites, measuring only 249 MPa, representing a nearly 50% decrease compared to binary skutterudites. Additionally, there is a noticeable drop in the elastic, bulk and shear modulus. With molecular dynamics calculations, the shear strength of S-doped skutterudites also follows a sharp drop at a small ultimate strain. The evolutions of atomic configurations reveal that the lattice strain induced by S-dopants softens the Sb-Sb bond, ultimately leading to structure collapse under low shear stress conditions. These findings underscore the necessity for a comprehensive approach to elemental doping in thermoelectric community.
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：
Chemical Engineering Journal,2024年482 ISSN：1385-8947
通讯作者：
Hou, HB;Lan, JR
作者机构：
[Cai, Yungao; Hou, Haobo; Xiang, Yuwei] Wuhan Univ, Sch Resource & Environm Sci, Wuhan, Peoples R China.;[Lan, Jirong] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.;[Dong, Yiqie] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan, Peoples R China.
通讯机构：
[Lan, JR ] H;[Hou, HB ] W;Wuhan Univ, Sch Resource & Environm Sci, Wuhan, Peoples R China.;Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.
关键词：
Nickel tailings;PMS-AOPs;Active radicals;Crystallographic plane;Density functional theory
摘要：
The use of nickel-cobalt tailings rich in nickel, cobalt, and iron to produce catalytic materials that drive advanced oxidation systems for PMS is a sustainable strategy. This study uses a combination of alkali modification and calcination to prepare a novel waste-based PMS-AOPs catalytic material (NCT-beta), and its catalytic activity against organic pollutants (RB-19, BPA, RhB, SMX, CBZ, and BA) was investigated under the activation of PMS, for first time. The characterization results showed that NCT-beta was modified into a multi-layer honeycomb with irregular surface, which can provide abundant active sites for chemical reactions, and expose metal elements on the surface of the material, promoting the electron transfer efficiency of organic pollutant degradation. The degradation rate of NCT-beta to RB-19 was 98.26 % within 30 min, and the catalytic efficiency was still more than 80 % when repeated use. Free radical pathway dominates the degradation process of organic pollutants, 1O2, & sdot;O2, and & sdot;OH are the main active radicals. Density functional theory (DFT) results indicate that the (020) crystal plane exposed by NCT-beta is the strongest site of action for pollutants and PMS. This study provides a solution for developing green environmental functional materials based on solid waste and treating waste with waste.
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.
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：
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.
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.
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/).
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.
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.
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.
