作者机构：
[Cai, Yong; Chen, Haijun; Fan, Xiaoyue] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;[Lv, XY; Lv, Xiaoyong] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
通讯机构：
[Lv, XY ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
摘要：
This paper proposes a solution for analyzing the flexural-torsional response of a thin-walled beam with an open mono-symmetric cross section and under moving loads induced by a moving mass. The additional torsional moment induced by the variation of the shear center location, lateral forces and rotary inertia are taken into consideration in the governing differential equations of motion. According to the Fourier finite integral transformation, the Laplace-Carson transformations and their inverse transformations, the analytical solutions are acquired for vibrational behaviors of beams. The reliability and advancement of the proposed analytical solutions are confirmed by comparing the analytical results originated from the proposed solution with those calculated by previous solutions in the relative literature. Based on the proposed solutions, an extensive parametric study is conducted to investigate the effect of the influential parameters on dynamic response of thin-walled beams, involving the additional torsional moment, lateral forces, velocities, eccentricities and mass of the moving object. The findings reveal that the additional torsional moment plays an important role in lateral displacements of thin-walled beams, especially for the beams subjected to excitation induced by a heavy mass moving at high velocities. Besides, lateral displacements increase with the rise of the additional torsional moment. It is also suggested that the rise of velocities of a moving mass, lateral forces, or eccentricities result in the growth of lateral displacements of beams.
作者机构：
[Yin, Qiang] Cent South Univ Forestry & Technol, Sch Mat Sci & Engn, Dept Forestry Engn, Changsha, Peoples R China.;[Wang, HQ; Zhao, Jinping; Wang, Hanqing; Li, Chengjun] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha, Peoples R China.;[Wang, HQ; Wang, Hanqing; Yin, Qiang] Cent South Univ Forestry & Technol, Hunan Engn Res Ctr Full Life Cycle Energy Efficien, Changsha, Hunan, Peoples R China.;[Mao, Yu] Univ Auckland, Sch Chem Sci, Auckland 1010, New Zealand.
通讯机构：
[Wang, HQ ] C;[Mao, Y ] U;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha, Peoples R China.;Cent South Univ Forestry & Technol, Hunan Engn Res Ctr Full Life Cycle Energy Efficien, Changsha, Hunan, Peoples R China.;Univ Auckland, Sch Chem Sci, Auckland 1010, New Zealand.
摘要：
The Fe-based Fischer-Tropsch synthesis (FTS) catalyst shows a rich phase chemistry under pre-treatment and FTS conditions. The exact structural composition of the active site, whether iron or iron carbide (FeCx), is still controversial. Aiming to obtain an insight into the active sites and their role in affecting FTS activity, the swarm intelligence algorithm is implemented to search for the most stable Fe(100), Fe(110), Fe(210) surfaces with different carbon ratios. Then, ab initio atomistic thermodynamics and Wulffman construction were employed to evaluate the stability of these surfaces at different chemical potentials of carbon. Their FTS reactivity and selectivity were later assessed by semi-quantitative micro-kinetic equations. The results show that stability, reactivity, and selectivity of the iron are all affected by the carbonization process when the carbon ratio increases. Formation of the carbide, a rather natural process under experimental conditions, would moderately increase the turnover frequency (TOF), but both iron and iron carbide are active to the reaction. The Fe-based Fischer-Tropsch synthesis (FTS) catalyst shows a rich phase chemistry under pre-treatment and FTS conditions.
作者机构：
[Jia, Haipeng] Tianjin Univ, Sch Civil Engn, Tianjin 300072, Peoples R China.;[Jia, Haipeng] Shenzhen Geotech Invest & Surveying Inst Grp Co Lt, Shenzhen 518028, Peoples R China.;[Wang, Ning] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Guan, Lingxiao; Wang, Ning; Ding, Haibin] East China Jiaotong Univ, State Key Lab Performance Monitoring & Guarantee R, Nanchang 330013, Peoples R China.
通讯机构：
[Wang, N ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;East China Jiaotong Univ, State Key Lab Performance Monitoring & Guarantee R, Nanchang 330013, Peoples R China.
关键词：
tunnel–soil–pile interaction;Kerr foundation model;lateral soil displacements;shielding effect;group piles
摘要：
The Kerr foundation model simulates the interaction between piles and soil. Considering the impact of lateral soil displacement on adjacent piles, the lateral displacement and bending moment of the adjacent piles caused by shield tunnel excavation are calculated in detail. Additionally, the reactions of groups of piles are obtained by focusing on the shielding effect of the piles on the soil displacement caused by shield tunnel excavation. The validity of the solutions is verified by comparing the calculated results with the boundary element program GEPAN. Additionally, adjacent pile lateral displacement and bending moment are compared, with and without considering lateral soil effects. Furthermore, this study investigates the influence of various factors, such as soil spring stiffness, pile-tunnel distance, ground loss ratio, and pile diameter on the pile group's lateral displacement and bending moment. The research findings indicate that increasing the soil spring stiffness or the horizontal distance between the pile and tunnel can reduce the lateral displacement and the bending moment of the pile. On the other hand, as the ground loss ratio gradually increases, the pile lateral displacement and bending moment will also increase. However, when the diameter of the pile grows, the lateral displacement reduces, while the bending moment increases.
摘要：
An orthogonal test of the component design of aerated concrete was carried out to solve the problems of low strength, easy cracking, and high water absorption of aerated concrete. The influences of cement content, water-binder ratio, foaming agent content, and polypropylene fiber content on the performances of aerated concrete including dry density, compressive strength, and thermal conductivity were investigated. Furthermore, the optimal composition of aerated concrete was determined. The test results showed that the dry density, compressive strength, thermal conductivity, and water absorption of aerated concrete were greatly influenced by the dosage of the foaming agent. Additionally, the water-binder ratio was found to significantly influence the apparent porosity of aerated concrete. Based on the experiment, the optimal combination of components for aerated concrete was 65 wt.% cement and 35% wt.% mineral admixture with a fly ash to slag ratio of 3:1. Meanwhile, the content of water-binder ratio, foaming agent, and polypropylene fibers were 0.4, 4 wt.%, and 0.4 wt.% of the total cementitious material, respectively. Among the mix proportions in this study, aerated concrete prepared by using the above mix proportion had the best performances. Subsequently, the influence of ceramsite content on the strength, dry density, and thermal conductivity of aerated concrete was analyzed. The results showed that the dry density and thermal conductivity of ceramsite aerated concrete increased with the increase of ceramsite content, but the change law of the water absorption was the opposite. Moreover, the compressive strength increased first and then decreased with the increase of ceramsite content, while the apparent porosity was the opposite. The optimal ceramsite content in ceramsite aerated concrete was 20 wt.%.& 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/).
通讯机构：
[Wu, H ] C;[Zhu, P ] T;Cent South Univ, Sch Civil Engn, Changsha 410075, Hunan, Peoples R China.;Tongji Univ, Coll Civil Engn, Shanghai 200092, Peoples R China.;Tongji Univ, Key Lab Performance Evolut & Control Engn Struct, Minist Educ, Shanghai 200092, Peoples R China.
关键词：
Introduction;Materials and Methods;Results;Discussion;Conclusion;Abstract;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interests;Authors’ Contributions;Funding Statement;Acknowledgements;Acknowledgments;Supplementary Materials;Reference;Dataset Description;Dataset Files;Abstract;Introduction;Introduction and Materials;Introduction and Methods;Materials;Materials and Methods;Methods;Results;Discussion;Results and Discussion;Discussion and Conclusion;Results and Conclusion;Conclusion;Conclusions;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interest;Authors’ Contributions;Funding Statement;Acknowledgements;Supplementary Materials;References;Appendix;Abbreviations;Preliminaries;Introduction and Preliminaries;Notation;Proof of Theorem;Proofs;Analysis of Results;Examples;Numerical Example;Applications;Numerical Simulation;Model;Model Formulation;Systematic Palaeontology;Nomenclatural Acts;Taxonomic Implications;Experimental;Synthesis;Overview;Characterization;Background;Experimental;Theories;Calculations;Model Verification;Model Implementation;Geographic location;Study Area;Geological setting;Data Collection;Field Testing;Data and Sampling;Dataset;Literature Review;Related Works;Related Work;System Model;Methods and Data;Experimental Results;Results and Analysis;Evaluation;Implementation;Case Presentation;Case Report;Search Terms;Case Description;Case Series;Background;Limitations;Additional Points;Case;Case 1;Case 2 etc.;Concern Details;Retraction Details;Copyright;Related Articles
摘要：
Permeable pavement materials are attracting great attention due to the superior benefits in fast drainage, driving safety, and noise reduction effectiveness. This study investigated the sound absorption behaviors of permeable pavement materials, including permeable cement concrete (PCC) and open-graded friction course asphalt mixture (OGFC). The sound absorption coefficients (SACs) of dense-graded cement concrete and dense-graded asphalt mixture were also measured for comparison. The sound absorption test was conducted by the impedance tube method according to ASTM E1050-19. Computed tomography (CT) scanning tests were conducted to obtain the pore characteristics of PCC and OGFC, including porosity distribution, pore size, and coordination number (CN). The porosity distribution, pore size distribution, and CN distribution presented a symmetrical trend of decreasing, then increasing, and then decreasing with the increase of specimen height. When OGFC and PCC showed similar porosities, the pore number of PCC was significantly larger than that of OGFC. Comparisons of the peak SAC and the average SAC were made between PCC and OGFC. Correlations were made between the SAC and the pore characteristics. Results indicated that with increasing porosity, the peak SAC and the average SAC both increased significantly for PCC and OGFC. The characteristic pore size, pore number, and CN distribution together affected the SAC. At the same porosity, OGFC mixtures presented larger average SAC compared to PCC, which was ascribed to the fact that more pores with larger size and a better pore connectivity existed in OGFC mixtures.
作者机构：
[Wu, Hao; Sun, Yuxuan; Song, Weimin; Zhan, Yiqun; Wu, Zhezheng] Cent South Univ, Sch Civil Engn, Changsha 410017, Peoples R China.;[Yin, Jian] Cent South Univ Forestry & Technol, Sch Civil Engn & Mech, Changsha 410004, Peoples R China.
通讯机构：
[Hao Wu] S;School of Civil Engineering, Central South University, Changsha 410017, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
The super absorbent polymer (SAP) has been attracting extensive concerns due to its strong capacity in water absorption and retention. The amorphous hydrogels formed by the post-absorbent SAP have the potential of clogging the micro-cracks in asphalt materials and refraining the rainwater from infiltrating. This provides the possibility of applying SAP in asphalt pavements to seal or fill the cracks and relieve the distresses caused by rainwater infiltration in the underlying layers. Before exploring the cracking sealing mechanism of SAPs in asphalt pavements, a series of experiments were performed to evaluate the feasibility and influences of SAPs in asphalt mastics and asphalt mixtures on their mechanical performances and functionalities. Firstly, the basic properties of SAPs were analyzed, and then the rheological properties of the asphalt mastics using SAP replacing mineral powder (10%, 20%, 30%, and 40% by volume) were explored. The water stability and infiltration reduction effect of the asphalt mixtures incorporated with SAP were evaluated by the Marshall stability test, immersion Marshall stability test, freeze-thaw splitting strength test, Cantabro test, and permeability test. The test results indicated that SAPs could be used in the asphalt mixtures to partially substitute mineral powder with desirable mechanical performances. When less than 10% of the mineral powder was replaced by the SAP, the high-temperature performance and fatigue life of the asphalt mastics could be improved to some extent, but both declined after the content of the SAP was larger than 10%. Due to the hydrogels formed by SAPs after water absorption, the water stability of the asphalt mixtures deteriorated with the increased content of SAPs. Moreover, the results from the permeability tests implied that the SAP hydrogels could fill the seepage channels in the material, thus improving the migration and infiltration resistances of the asphalt mixtures. With the increased contents of SAPs, the permeability coefficients of the asphalt mixtures could be reduced up to 55%. Based on the research findings in this study, when an appropriate amount of SAP was added in the asphalt materials, desirable temperature stability, water stability, and fatigue resistance could be achieved regarding actual requirements from applications. At the same time, the addition of SAPs could effectively refrain the infiltration and migration of rainwater in asphalt pavements, thus potentially mitigating the effect of water erosion on the underlying layers.
摘要：
In response to the deformation resistance deficiency and poor toughness characteristics of soil after microbial curing, a combination of fibre reinforcement technology and microbial curing technology was used to conduct microbial curing tests using basalt fibres and denitrifying bacteria. In this paper, the effects of fibre on the strength and toughness of soil consolidation were analysed by unconfined compressive strength test and direct shear test, and the stability of reinforced slope was analysed by numerical simulation. The results show the following. (1) Basalt fibre can effectively improve the characteristics of brittle damage of microbially consolidated soil while increasing the compressive and shear strength. (2) Fibre dosing and fibre length have important effects on the mechanical properties of microbially consolidated soil. (3) The appropriate amount of basalt fibre can promote the generation of calcium carbonate. (4) The plastic strain area of the slope decreases after microbial reinforcement and the maximum equivalent plastic stress decreases by 65 kPa.
期刊：
Bulletin of Engineering Geology and the Environment,2023年82(12):1-16 ISSN：1435-9529
通讯作者：
Wenchen Fan
作者机构：
[Wenchen Fan; Hui Yang] School of Civil Engineering, Central South University of Forestry and Technology, Changsha, China;[Guodong Tang] China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan, China;[Dongya Han] School of Resources and Safety Engineering, Central South University, Changsha, China
通讯机构：
[Wenchen Fan] S;School of Civil Engineering, Central South University of Forestry and Technology, Changsha, China
摘要：
Fractures are commonly found throughout rock masses. The propagation and coalescence of these fractures can significantly weaken the surrounding rock strength during underground excavations. In order to investigate the cracking behavior of pre-existing fractures affected by excavation unloading, this study proposed an innovative laboratory excavation test to simulate excavation unloading in deep rock masses. Corresponding numerical stepped excavation tests were also conducted using RFPA (Realistic Failure Process Analysis). The excavation area in specimen was pre-filled with polylactic acid (PLA), and stepped excavation under constant normal stress was performed using an electric cutter. The results reveal that the stress-strain curves of the specimens during stepped excavation can be categorized into four stages based on deformation behavior and the crack process. There are four different patterns of crack coalescence, ultimately leading to specimen failure. Numerical results indicate that the inhomogeneous deformation caused by stepped excavation is responsible for crack initiation, propagation, and eventual specimen failure. The rock bridges between fissures and excavation areas break in three modes: shear sliding, segregation due to tensile cracks, and the formation of ubiquitous fractures. Furthermore, the inclination of the fissure and the initial normal load applied to the specimens have a significant impact on the crack coalescence modes and initiation. These findings can contribute to a better understanding of crack evolution behaviors, including initiation, propagation, coalescence, and transfixion, during excavation unloading in underground engineering projects.
