期刊：
Construction and Building Materials,2023年397:132364 ISSN：0950-0618
通讯作者：
Xu, F
作者机构：
[Xu, Fang; Dong, Junli; Yang, Qi; Leng, Wuming; Zhang, Qishu] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;[Yang, Qi; Leng, Wuming; Xu, Fang] Cent South Univ, MOE Key Lab Engn Struct Heavy Haul Railway, Changsha 410075, Peoples R China.;[Zhang, Qishu] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Li, Yafeng] Anhui Univ Sci & Technol, Sch Civil Engn & Architecture, Huainan 232001, Peoples R China.;[Wu, Shuangshuang] Hohai Univ, Sch Earth Sci & Engn, Nanjing 211100, Peoples R China.
通讯机构：
[Xu, F ] C;Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.
关键词：
Fine breccia soil subgrade;Prestressed reinforcement structure;Scale model test;Dynamic response;Numerical simulation
摘要：
Train cyclic loading generally results in significant dynamic responses of the breccia soil subgrade, resulting in a series of subgrade problems. A new prestressed reinforcement structure (PRS) is proposed to reinforce subgrade structures. However, characteristics of the prestressed subgrade under dynamic loading have not been investigated. This study investigates the vibration characteristics of a new prestressed subgrade structure under train cyclic loading. The acceleration responses of the subgrade surface under different train axle loads and prestress levels are measured and discussed by developing a 1:5 scale dynamic model test on a prestressed fine breccia soil subgrade structure. Subsequently, a three-dimensional dynamic finite element model of the prestressed subgrade is constructed for an in-depth analysis of the internal acceleration of the prestressed subgrade. The results showed that a periodic acceleration response of the subgrade should be observed, and its mean crest and mean trough are used to characterize the long-term vibration degree of the subgrade. The peak vertical acceleration of the subgrade is significantly affected by the prestress level, and the dynamic response of the subgrade around the lateral pressure plate (LPP) is reduced more obviously by the prestress than that of the subgrade's inner region. The peak vertical acceleration at the subgrade shoulder presents linear increase and exponential attenuation with the rise in the train axle load and prestress level, respectively. In addition, an empirical model describing the relationships among the peak acceleration, train axle load, and prestress is proposed. The vertical dynamic displacement and dynamic stress decrease with the increase of the prestress. The average elastic deformation and peak dynamic stress of the subgrade under a prestress level of 100 kPa are found to be 95.8% and 87.22-90.07% of that with the absence of prestress, respectively. The vertical vibration of the prestressed subgrade structure can be reduced by taking measures such as adjusting the prestress magnitude and increasing the subgrade slope ratio, thereby achieving an effective prestress reinforcement effect.
作者：
Liu Menglu;Liu Peng*;Wu Jun;Yu Zhiwu;Chen Ying;...
期刊：
Construction and Building Materials,2023年400:132842 ISSN：0950-0618
通讯作者：
Liu Peng
作者机构：
National Engineering Research Center for High Speed Railway Construction, Changsha 410075, China;China Railway Group Ltd., 69 Fuxing Road, Beijing 100039, China;School of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, China;School of Civil Engineering, Central South University of Forestry and Technology, 498 Shaoshan Road, Changsha 410004, China;[Liu Menglu; Liu Peng; Yu Zhiwu; Cheng Xiang] National Engineering Research Center for High Speed Railway Construction, Changsha 410075, China<&wdkj&>China Railway Group Ltd., 69 Fuxing Road, Beijing 100039, China<&wdkj&>School of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, China
通讯机构：
[Liu Peng] N;National Engineering Research Center for High Speed Railway Construction, Changsha 410075, China<&wdkj&>China Railway Group Ltd., 69 Fuxing Road, Beijing 100039, China<&wdkj&>School of Civil Engineering, Central South University, 22 Shaoshan Road, Changsha 410075, China
摘要：
The silicone waterproof material and waterbased capillary inorganic waterproofer possess the advantages of rapid film formation and significant hydrophobic effect. In this study, the material composition and mixing ratio of the silicone waterproofing material and waterbased capillary inorganic waterproofing were investigated by multiple performance tests. The results indicated that a white coating was formed on the surface when the mixing ratio of isobutyl-triethoxy-silane and isooctyl-triethoxy-silane was more than 69 %. When the content of sodium and potassium methyl silicate exceeded 0.5 %, respectively, there was an upward trend of contact angle while the reduction in water absorption gradually decreased. Meanwhile, the contact angle and water absorption height of silicone waterproof material were tested. The results showed that the coating performance and hydrophobicity were the best when the mixing ratio of isobutyl-triethoxy-silane, isooctyl-triethoxy-silane, sodium methyl silicate, and potassium methyl silicate was 1.5:0.2:1:0.5. When the matrix mortar specimen was made of Cementitious Capillary Crystalline Waterproofing Materials (CCCW), the lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose were 316.7 % and 39%, respectively. The lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, nano-silica, and sodium hydroxyethyl cellulose were 215.4 % and 28 %, respectively. The results showed that CCCW combined with the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose had better waterproofing effect.
摘要：
Cylinders as a common form of bridge piers are widely used in engineering practices, yet the hydrodynamic forces and local scouring of the cylinder due to the fluid flow cause significant concern about the functionality of circular bridge piers. In this paper, two novel auxiliary structural types are proposed for passive control of flow around bridge piers, and their optimal structural parameters are determined efficiently using a surrogate model -based hydrodynamic shape optimization framework. Specifically, a Kriging-based active learning algorithm is proposed for hydrodynamic shape optimization of auxiliary structures, which are placed at the rear and both the front and rear of a cylinder. The hydrodynamic performance of the circular bridge pier with the optimized auxiliary structures (F3 and F6) is investigated through 2D and 3D numerical simulations. The effectiveness of the optimized auxiliary structures in mitigating the adverse effect of local scouring around a cylinder is also revealed through a case study. Results indicate that the optimized auxiliary structures F3 and F6 can dramatically reduce the drag coefficient compared with the bare cylinder, i.e., with a reduction rate of 69.8% and 77.2%, respectively; and the reduction rate is more pronounced for the lift coefficient, i.e., with a reduction rate higher than 90% for both F3 and F6. The reduction of drag and lift coefficients is mainly attributed to the positive effects of the optimized auxiliary structures for adjusting the pressure distribution around the cylinder, elongating the free shear layer, improving the wake stability etc. Interestingly, the auxiliary structure F6 also exhibits a high potential to mitigate the scouring effect of fluid flow around a cylinder by decreasing the flow velocity and bed shear stress around the cylinder. However, it should be noted that placing the auxiliary structure at the rear of a cylinder (such as the auxiliary structure type F3) could introduce an adverse effect on reducing local scouring. This study provides valuable guidance for designing effective auxiliary structures for passive control of fluid flow around cylinders.
摘要：
This paper presents analytical solutions for the dynamic response of thin-walled curved beams induced by moving vehicles. The solutions encompass vertical, torsional, radial, and axial motions. A comprehensive set of governing equations for the dynamic response of thin-walled curved beams is established by considering the mass inertia of moving vehicles, rotary inertia, and warping resistance. The solutions are obtained for the four-directional response of curved beams, involving vertical, torsional, radial, and axial motions, based on the Fourier finite integral transformation, the Laplace–Carson transformation, their inverse transformations, and the Galerkin approach. A comparison of the results calculated by the analytical solutions in this study are compared with those calculated by the moving-force solutions using the Galerkin approach reported in a related literature, demonstrates the reliability and superiority of the analytical solutions. Hence, an extensive parametric study is carried out to investigate the effect of the mass inertia of moving vehicles, velocities, higher-order modes of vibrations, and radii of curvature on the dynamic responses of beams. As per the results, the mass and velocity of the moving vehicles play important roles in the dynamic response of curved beams. Furthermore, the dynamic response for thin-walled curved beams increases significantly with heavier vehicles and higher velocities, confirming that it is necessary to consider the mass inertia effect to study the dynamic response of curved beams.
作者：
Xue-feng Ou Ph.D.;Xue-min Zhang Ph.D.;Han Feng Ph.D.*;Cong Zhang Ph.D.;Shu-ying Wang Ph.D.;...
期刊：
International Journal of Geomechanics,2023年23(7):05023004 ISSN：1532-3641
通讯作者：
Han Feng Ph.D.
作者机构：
[Xue-min Zhang Ph.D.; Shu-ying Wang Ph.D.] Professor, School of Civil Engineering, Central South Univ., Changsha 410018, Hunan, China;[Cong Zhang Ph.D.] Associate Professor, School of Civil Engineering, Central South Univ. of Forestry and Technology, Changsha 410004, Hunan, China;[Xue-feng Ou Ph.D.] Lecturer, National Engineering Laboratory of Highway Maintenance Technology, Changsha Univ. of Science & Technology, Changsha 410114, Hunan, China;[Han Feng Ph.D.] Lecturer, School of Safety Engineering and Emergency Management, Shijiazhuang Tiedao Univ., Shijiazhuang 050048, Hebei, China (corresponding author);[Xian-shun Zhou Ph.D.] Doctoral Candidate, School of Civil Engineering, Central South Univ., Changsha 410018, Hunan, China
通讯机构：
[Han Feng Ph.D.] L;Lecturer, School of Safety Engineering and Emergency Management, Shijiazhuang Tiedao Univ., Shijiazhuang 050048, Hebei, China (corresponding author)
摘要：
The field measurements and numerical simulations were conducted to evaluate the response of the nearby metro tunnels to the construction of diaphragm walls in Shenzhen, China. Results showed that the diaphragm wall construction significantly affects the metro tunnels’ horizontal deformation. The diaphragm wall construction was numerically modeled to perform a parametric study. The results showed that the concreting stage could reduce the differential deformation of the tunnel structure, thus effectively reducing the internal force of the tunnel structure. The synchronous interval construction of the diaphragm wall was more conducive to controlling deformation than the single-wall constructs in sequence. Further, the horizontal displacement of the metro tunnels at different locations on the diaphragm wall was evaluated. Finally, soil strengthening is discussed as an effective measure for protecting metro tunnels from being affected by diaphragm wall construction. This study helps assess the potential response of metro tunnels to adjacent diaphragm wall construction for new deep excavation projects or future workings.
期刊：
Indian Geotechnical Journal,2023年53(2):283-290 ISSN：0971-9555
通讯作者：
Chang-ping Wen
作者机构：
[Xiang Tang; Chang-ping Wen] Civil Engineering Department, School of Civil Engineering, Central South University of Forestry and Technology, Changsha, People’s Republic of China
通讯机构：
[Chang-ping Wen] C;Civil Engineering Department, School of Civil Engineering, Central South University of Forestry and Technology, Changsha, People’s Republic of China
关键词：
Double yield surfaces constitutive model;Lime-treated weathered red sandstone soil;Road engineering;Stress–strain relation;Test study
摘要：
In this work, a series of triaxial consolidated drained shear tests were used to investigate the stress–strain relationships of weathered red sandstone soil and lime-treated weathered red sandstone soil. Firstly, the triaxial consolidated drained shear test results were used to analyze the relationship between deviatoric stress
$$q$$
, axial strain
$${\varepsilon }_{1}$$
, shear strain
$${\varepsilon }_{\mathrm{s}}$$
, and volume strain
$${\varepsilon }_{\mathrm{v}}$$
. Secondly, the yield surface of the soil was divided into the volume yield surface and shear yield surface, and two yield surfaces were assumed as ellipse and parabola, respectively. The ellipse volume yield surface and the parabola shear yield surface were fitted based on
$${\varepsilon }_{\mathrm{v}}-{\varepsilon }_{1}$$
,
$$q-{\varepsilon }_{\mathrm{s}}$$
test results, respectively. Finally, based on the ellipse-parabola constitutive model, the elastoplastic constitutive equations with double yield surfaces of weathered red sandstone soil and lime-treated weathered red sandstone soil were constructed. This provides a basis for the numerical analysis of the deformation of red sandstone weathered soil and lime-treated red sandstone weathered soil.
通讯机构：
[Liu, J ] C;Cent South Univ Forestry & Technol, Hunan Prov Key Lab Engn Rheol, Changsha 410004, Peoples R China.;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
摘要：
Research efforts have intensified on developing superhydrophobic surfaces on concrete structures to limit the damage caused by the natural porosity and hydrophilicity of cementitious materials. However, the feasibility idea is impeded by the complex preparation process and weak adhesion/stability performance. Therefore, superhydrophobic coatings were rapidly prepared on mortar surfaces by a straightforward and effective one-step method using zinc oxide (ZnO) modified with stearic acid and epoxy resin. The microstructure, physical/chemical properties, hydrophobic properties, and stability of the coatings were systematically investigated. The experimental results showed that the water contact angle of the samples reached a maximum value of 164.2° and a sliding angle of 4.6° when the stearic acid content was 0.5 g. The water absorption of the coated superhydrophobic mortar was reduced by approximately 61% compared to that of ordinary mortar, and neither particulate pollutants nor liquid pollutants could contaminate the superhydrophobic mortar. The coating maintained a superhydrophobic state and exhibited good physical durability after sandpaper abrasion, tape peeling, and high-temperature resistance tests. The water cluster diffusion coefficient on surface of the ordinary coating was 0.1645 × 10(-4) and 0.0328 × 10(-4) cm(2)/s on surface of the modified coating after molecular dynamics simulation.
期刊：
International Journal of Pavement Research and Technology,2023年:1-12 ISSN：1996-6814
通讯作者：
Kefei Liu<&wdkj&>Kang Jiang
作者机构：
[Luyue Wang; Kefei Liu] School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China;Hunan Provincial Engineering Research Center for Construction Solid Wastes Recycling, Changsha, People’s Republic of China;[Kang Jiang] Hunan Communications Research Institute Co. LTD, Changsha, People’s Republic of China;[Quan Li] School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China<&wdkj&>Hunan Provincial Engineering Research Center for Construction Solid Wastes Recycling, Changsha, People’s Republic of China
通讯机构：
[Kefei Liu] S;[Kang Jiang] H;School of Civil Engineering, Central South University of Forestry & Technology, Changsha, People’s Republic of China<&wdkj&>Hunan Communications Research Institute Co. LTD, Changsha, People’s Republic of China
摘要：
To provide theoretical and data support for the fatigue performance test and life prediction of rejuvenated asphalt mixture, and supply parameter support for the design of rejuvenated asphalt pavement, dynamic shear rheometer (DSR) was used to conduct repeated shear tests on original asphalt, wood tar-based rejuvenated asphalt and RA-102 rejuvenated asphalt to evaluate the rationality of three parameters are defined as follows: complex modulus parameter (Nf50), dissipated energy ratio parameter (NP20), ratio of dissipated energy change parameter (Nfm) for evaluating the fatigue performance of rejuvenated asphalt, and the fatigue life prediction equation of wood tar-based rejuvenated asphalt was established considering the influence of temperature. The results show that NP20 has clear definition and accurate calculation of asphalt fatigue life, and takes into account the change of internal energy of asphalt material, which can be used as evaluation parameter of fatigue performance of wood tar-based rejuvenated asphalt. The fatigue performance of wood tar-based rejuvenated asphalt decreases with the increase of the temperature. The fitted prediction equations can accurately predict the fatigue life of wood tar-based rejuvenated asphalt.
