期刊：
Mechanics Based Design of Structures and Machines,2023年51(6):3004-3025 ISSN：1539-7734
通讯作者：
Xian-Fang Li
作者机构：
[Zhang, Xue-Yang; Peng, Yi; Li, Xian-Fang] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.;[Peng, Yi] Hunan City Univ, Sch Civil Engn, Yiyang, Peoples R China.
通讯机构：
[Xian-Fang Li] S;School of Civil Engineering, Central South University, Changsha, PR China
关键词：
Heat-moisture coupling;convective boundary;non-Fourier effect;hygrothermal stresses;phase lag
摘要：
In this article, by considering the Dufour effect and Soret effect, a hygrothermal coupling model based on phase delay of heat and moisture fluxes is established for convective surfaces. The convective surfaces are described by Robin boundary conditions. The Dirichlet boundary conditions (prescribed temperature and moisture on the surfaces) and Neumann boundary conditions (prescribed heat and moisture fluxes) are two extreme cases of the Robin conditions. Using Laplace transform, the effects of different relaxation times and moist-heat coupling on the temperature, moisture, and stress of the hollow cylinder are analyzed from two aspects of time and space. For convective boundary, the dependence of temperature, moisture, and stress on the phase lag of heat and moisture fluxes is examined. The results show that the temperature and moisture distributions along with the hygrothermal stress fields exhibit different behaviors, depending on the coefficient of Robin condition.
作者机构：
[Zhang, Yinghui; Zhang, Jinfan; Wang, Da; Chen, Yun] Changsha Univ Sci & Technol, Dept Transportat Engn, Changsha 410114, Peoples R China.;[Zhang, Jinfan] Hunan City Univ, Dept Civil Engn, Yiyang 413000, Peoples R China.
通讯机构：
[Jinfan Zhang] D;Department of Civil Engineering, Hunan City University, Yiyang 413000, China<&wdkj&>Department of Transportation Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
construction megaproject team;multiteam system;team learning
摘要：
The construction megaproject team (CMPT) emphasises integration as a megaproject multiteam system (MTS) to facilitate knowledge learning. This paper synthesises the CMPT structure characteristics and team learning processes into a conceptual framework named the CMPT-MTS learning framework to advance future CMPT learning research. The constructs included are identified from published research. A case example is the island and tunnel project of the Hong Kong–Zhuhai–Macao Bridge, which provides practical grounding for framework refinement. The conceptual framework deemed to follow a cyclical pattern identifies the CMPT-MTS structure variables and team learning processes affecting learning outcomes and contextual variables hypothesised to influence the intra- and inter-team interaction. We discuss how the conceptual framework might identify the CMPT learning research gaps for future research. The framework’s contribution to the body of knowledge expands our lens to understand team learning practices in the complex CMPT by considering CMPT as an MTS.
摘要：
Reasonable assessment of corrosion initiation probability in existing reinforced concrete structures is an important premise for ensuring the safety and durability of such structures. In this paper, a simplified dual time-dependent chloride diffusion model considering the load effect is established and verified by comparing its results with the experimental data. Then, a modelling method of imprecise random fields is developed. In addition, a novel probabilistic analysis method of corrosion initiation in existing RC structures with imprecise random fields is proposed. The case analysis results show that the corrosion resistance of existing structures will be overestimated without considering the effect of imprecise random fields. In comparison, the upper bound of cumulative probability of corrosion initiation is 2.29 times of that using the existing deterministic method in this case. Parametric analyses show that the imprecise random field of concrete cover (Cd) has the greatest effect on the cumulative probability of corrosion initiation, followed by initial surface chloride concentration (Cs) and chloride diffusion coefficient (Da). Compared with the interval coefficient of variation and correlation length, the cumulative probability of corrosion initiation is more sensitive to the interval mean, especially the interval mean of Cd. Additionally, the effect of interval correlation length of Cs is sequentially greater than that of Cd and Da.
作者机构：
[Chen, Yi; Xue, Yanghao; Zhao, Changjie; Liu, Chang] Guizhou Univ, Sch Civil Engn, Guiyang 550025, Guizhou, Peoples R China.;[Rao, Junying; Rao, JY] Guizhou Univ, Res Ctr Space Struct, Guiyang 550025, Guizhou, Peoples R China.;[Chen, Yi; Xue, Yanghao; Zhao, Changjie; Liu, Chang] Guizhou Prov Key Lab Rock & Soil Mech & Engn Safe, Guiyang 550025, Guizhou, Peoples R China.;[Yin, Quan] Hunan City Univ, Sch Civil Engn, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Rao, JY ] G;Guizhou Univ, Res Ctr Space Struct, Guiyang 550025, Guizhou, Peoples R China.
摘要：
To investigate the mechanical properties of fractured dolomite, this study analyzed the fracture characteristics (dip angle, length, position, quantity) using the Pearson coefficient and MIC coefficient. Subsequently, the data pertaining to fracture characteristics is preprocessed using a third-degree polynomial, and a three-classification strategy is implemented to improve the logistic regression algorithm to establish the strength prediction model of fractured dolomite. Furthermore, the significance order of the impact of fracture characteristics on rock strength was determined using the numerical simulation software PFC3D, and the dip angle effect was explained from the perspective of internal fracture propagation within the rock. The results show that: (1) When the regularization coefficient λ = 10,000, the algorithm has the highest prediction accuracy and the strongest model generalization ability. (2) The numerical simulation analysis software PFC3D can accurately invert rock failure process and characteristics, and the order of influence of fracture characteristics on rock strength is dip angle > length > position.
作者机构：
[Peng, Zhigao; Peng, ZG; Deng, Zongwei; Feng, Haoxiong; Xiao, Ming] Hunan City Univ, Coll Civil Engn, Yiyang 413000, Peoples R China.;[Liu, Shenggui] China Univ Min & Technol Beijing, Sch Mech & Civil Engn, Beijing 100083, Peoples R China.;[Peng, Zhigao; Peng, ZG] Hunan City Univ, Hunan Engn Res Ctr Struct Safety & Disaster Preven, Yiyang 413000, Peoples R China.
通讯机构：
[Peng, ZG ] H;Hunan City Univ, Coll Civil Engn, Yiyang 413000, Peoples R China.;Hunan City Univ, Hunan Engn Res Ctr Struct Safety & Disaster Preven, Yiyang 413000, Peoples R China.
摘要：
Under specific conditions, moisture in natural coal seams can be adsorbed in the pores of the coal matrix, reducing the amount of methane adsorption sites and the effective area of the transport channels. This makes the prediction and evaluation of permeability in CBM exploitation more challenging. In this paper, we developed an apparent permeability model of coalbed methane coupling viscous flow, Knudsen diffusion, and surface diffusion which considers the effects of adsorbed gas and moisture in the pores of the coal matrix on the permeability evolution. The predicted data of the present model are compared with those of other models, and the results show good agreement, verifying the accuracy of the model. The model was employed to study the apparent permeability evolution characteristics of coalbed methane under different pressure and pore size distribution conditions. The main findings are as follows: (1) moisture content increases with saturation, with a slower increase for smaller porosities and an accelerated non-linear increase for porosities greater than 0.1. (2) Gas adsorption in pores decreases permeability, further weakened by moisture adsorption under high pressure but negligible at pressures below 1 MPa. (3) Higher water saturation weakens gas transport capacity, especially with pore sizes smaller than 10 nm. (4) The non-Darcy effect weakens with higher initial porosity, and neglecting moisture adsorption may significantly deviate from actual values in modeling methane transport in coal seams. The present permeability model can capture the transport characteristics of CBM in moist coal seams more realistically and is more applicable for predicting and evaluating the gas transport performance under dynamic variations of pressure, pore size, and moisture. The results in this paper can explain the transport behavior of gas in moist, tight, porous media and also provide a foundation for coalbed methane permeability evaluation.
摘要：
In this study, the rectangular pipe-jacking tunnel project of the Liuye Avenue West Extension under the Changzhang Highway is used to study highway pavement settlement and deformation during pipe-jacking construction through on-site monitoring. A three-dimensional numerical simulation method is employed to analyse the factors contributing to the significant settlement and rebound of the pavement. This study identifies the fundamental law governing the development of pavement settlement over time. The findings indicate that settlement increases rapidly when the jacking distance reaches approximately 10 m and then stabilizes at a consistent growth level. Furthermore, completion of the jacking of the left pipe leads to a transition in the surface settlement groove from a "V"-type distribution to a "W"-type distribution. Comparative analysis reveals that horizontal and vertical displacements exhibit similar characteristics, with maximum displacements occurring in the lagging jacking area. On both sides of the axis, the settlement groove curve remains stable within a range of 30-40 m, while the horizontal displacement curve stabilizes within a range of 20-30 m.
摘要：
Corrosion can accelerate the deterioration of the mechanical properties of orthotropic steel bridge decks (OSBDs), seriously affecting the service safety of steel bridges. In this paper, thirty Q345C steel and four OSBD specimens with various corrosion levels are designed to investigate the effect of corrosion on the static behavior of OSBDs. Then, corrosion damage and its influence on mechanical properties are explored by static loading experiments. The constitutive model for Q345C steel is built considering the impact of corrosion. Finally, a numerical analysis considering geometric initial defects is employed to compare the effect of corrosion location on bearing capacity degradation. It is observed from the tested results that the corrosion led to the failure mode of Q345C steel changing from plastic failure to brittle failure. The ultimate bearing capacity of specimens with a local corrosion rate of 7.92%, 12.05%, and 16.24% decreased by 11.08%, 14.45%, and 17.82%, respectively. Corrosion leads to stress concentration in the top plate area, causing local instability of the structure. The degradation degree of the bearing capacity of the top plate is greater than that of the U-rib corrosion corresponding to the same corrosion conditions.
通讯机构：
[Jianxin Peng ] P;Professor, Key Laboratory of Bridge Engineering Safety Control by Department of Education, School of Civil Engineering, Changsha University of Science and Technology, Changsha, Hunan, China
摘要：
A test was carried out to study the interface shear strength between carbonated concrete substrate and self-compacting concrete (SCC) overlay. One hundred and fourteen Z-type specimens were designed and subjected to direct shear tests. The influence of four interface treatment methods, three strengthening schemes and SCC strength on interface shear strength were discussed. Two coefficients considering the influence of interface treatment method and strengthening scheme on interface shear strength between carbonated concrete and SCC were developed. The results show that interface shear strength is affected not only by SCC strength but also by the strengthening scheme for the same interface treatment method, which increases with the increase of overlay strength for the same interface treatment method and strengthening scheme. The position of groove has little influence on interface shear strength for grooved specimens. Implanting steel bar is the most effective way to improve interface shear strength. When the carbonation time is around 60 days, the interface shear strength is increased by about 17%. The theoretical interface shear strength obtained by the developed model agreed well with tested values. The mean ratio of tested interface shear strength to theoretical strength is 0.86.
关键词：
finite difference time domain (FDTD);reverse time migration (RTM);finite difference time domain reverse time migration (FDTD-RTM);wavelet multi-resolution analysis;super-resolution reconstruction method
摘要：
The finite difference time domain (FDTD) method was used to solve the Maxwell's equation to obtain the reverse time migration (RTM) of ground penetrating radar (GPR) signals, namely, the finite difference time domain reverse time migration (FDTD-RTM). In order to ensure that the correct numerical solution of iterative calculation was achieved, it was necessary to obtain high-resolution signals, which greatly limits the applicability of FDTD-RTM in engineering. Based on the characteristics of wavelet multi-resolution analysis, this study proposed a super-resolution signal reconstruction method to improve signal resolution, with the view to completely solving the problem of FDTD-RTM limitation caused by insufficient signal sampling using GPR. The results of electromagnetic simulation showed that the signals reconstructed by the above method were highly similar to the signals sampled with the same resolution. On this basis, reverse time migration electromagnetic simulation and physical model tests were designed. The results of both experiments showed that the under-sampled GPR signals could achieve FDTD-RTM following super-resolution reconstruction, and that the migration imaging results of the target were basically consistent with the design scheme. The signal super-resolution reconstruction method based on the wavelet theory was thus shown to successfully achieve the overall application of FDTD-RTM in GPR signal analysis.
摘要：
In this study, a novel three-dimensional semi-rigid steel joint with a channel steel component is proposed, in which the channel steel component is connected to the column flange through a hybrid connection of bolts and welds along the minor axis. The design of the minor axis connection in this study had no weakening effect on the column web, and it was more convenient and easier to attach the additional channel steel component than the additional plates to the column flanges by welding. In order to investigate the static behaviour and seismic performance of the proposed novel three-dimensional semi-rigid steel joint with a channel steel component and to evaluate the interaction between both axes, numerical analyses were conducted systematically. The finite element (FE) models are firstly calibrated against the experimental results in order to get accurate results, and then the rotating characteristics, joint moment capacity, joint stiffness, ductility and energy dissipation capacity of the proposed novel semi-rigid steel joints were analysed under ten loading cases along the major and minor axes. The results indicate that the proposed novel semi-rigid steel joint has good energy dissipation capacity and deformation performance. Loading in the major-axis direction has almost no influence on the ultimate joint moment capacity but has some influence on the initial stiffness, ductility, stiffness degradation and energy dissipation ability of the proposed novel semi-rigid steel joint along the minor axis. In addition, the modified moment-rotation (M-theta) hysteretic model for the proposed novel semi-rigid steel joint is capable of effectively characterising its hysteretic behaviours, which can provide a reference for practical applications.
