摘要：
According to the influence law of various factors on the probability of coal spontaneous combustion, the degree of dependence of coal spontaneous combustion on each factor is analyzed and sorted. Abstract Coal spontaneous combustion is determined by a variety of factors. Testing can describe the changes incoal spontaneous combustion with various factors, however, the dependence of spontaneous combustion on various factors is unclear. Therefore, reliability theory was used to deduce the functional relationship of the dependence of coal spontaneous combustion on various factors, and construct a model algorithm for predicting the probability of occurrence of coal spontaneous combustion, which is adopted to evaluate and rank the degree of influence of various factors on coal spontaneous combustion. Effective prevention methods are proposed by strengthening the role of the most important factors. The results show that, by taking the duration of coal heating to 150°C as the measurement standard of coal spontaneous combustion, the duration of the initial stage of coal heating increases linearly with the increase of specific heat capacity, thermal conductivity, and moisture content of coal. With the increase of oxygen concentration, oxidation rate, and initial temperature of the coal, the duration of the initial stage of coal heating decreases exponentially. With the increase of gas flow seepage velocity in the coal body, the duration of the initial heating stage changes in a parabolic manner. At the same time, the probability of spontaneous combustion decreases exponentially with the increase of specific heat capacity and moisture content of the coal. The probability of coal spontaneous combustion increases linearly with the increase of coal thermal conductivity, oxygen concentration, gas seepage velocity, and rate of oxidation. The dependence of coal spontaneous combustion probability on different factors can be expressed as follows: coal temperature > gas seepage velocity > specific heat capacity > oxidation rate > oxygen concentration > moisture content > thermal conductivity.
摘要：
Spatial damage identification is of great significance in mechanical, aerospace, and civil engineering. In this study, a data coupling method based on continuous wavelet transform (CWT) is proposed to identify the spatial damage location of beam-type structures. The singularity of the wavelet coefficient can be used to identify the signal singularity, and data coupling method calculates the spatial location of the damage. Numerical simulations and experimental analyses of different type of beams with transfixion damage are carried out to evaluate the accuracy of the method. The results show that the wavelet based data coupling method (W-DCM) can identify the minimum 4.9% damage severity of fixed beam and continuous beam, and can also identify the damage of non-free end of cantilever beam. However, the 9.7% damage severity of the free end of the cantilever beam cannot be identified. It is also found that the W-DCM can effectively circumvent the problem of wavelet coefficients edge effect. This method and wavelet singularity are used to provide a solution to the problem of structural edge damage identification.
作者机构：
[Yi, Xinxiang; Wang, Guanci] Yueyang Rd & Bridge Grp Co Ltd, Yueyang 414000, Peoples R China.;[Luo, Zhengdong; Yi, Xinxiang; Liu, Yuming; Wang, Guanci; Zhang, Benben] Xiangtan Univ, Coll Civil Engn, Xiangtan 411105, Peoples R China.;[Zhang, Genbao] Hunan City Univ, Coll Civil Engn, Yiyang 413000, Peoples R China.;[Liu, Yuming] Hengyang Highway & Bridge Construct Co Ltd, Hengyang 421001, Peoples R China.
通讯机构：
[Benben Zhang; Genbao Zhang] A;Authors to whom correspondence should be addressed.<&wdkj&>College of Civil Engineering, Hunan City University, Yiyang 413000, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>College of Civil Engineering, Xiangtan University, Xiangtan 411105, China
摘要：
Sulfate attack is one of the non-negligible factors that induces deterioration in the performance and life cycle of soil stabilizers. In this paper, the degradation mechanism of the durability of slag–fly-ash-based geopolymer stabilized soft soil (hitherto referred to as SF-GSSS) under the sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4) attack environment is comparatively investigated, and the slag/fly ash ratios are set to S10F0, S9F1, S8F2, and S7F3. The SF-GSSS was fully immersed in a 2.5% Na2SO4 solution and 2.5% MgSO4 solution, respectively, to characterize the deterioration rules via visual observations, an unconfined compressive strength (UCS) test, and by mass change. The effect of sulfate on the microstructural characteristics of the SF-GSSS were determined by different microanalytical means, such as by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the SF-GSSS immersed in a MgSO4 solution displayed significant physical deterioration, but not when in a Na2SO4 solution. The mass growth of the SF-GSSS when immersed in a Na2SO4 solution was significantly lower than when it was immersed in a MgSO4 solution at the same immersion age. The rate of strength loss was lowest for S9F1 and highest for S7F3 at the end of immersion, regardless of its immersion in Na2SO4 or MgSO4 solutions.
作者机构：
[Yang, Rihua; Wang, Xinzhong; Yang, Yiming] Hunan City Univ, Sch Civil Engn, Yiyang 413000, Peoples R China.;[Yang, Rihua] Hunan City Univ, Hunan Engn Res Ctr Dev & Applicat Ceramsite Concre, Yiyang 413000, Peoples R China.;[Yang, Rihua] Hunan City Univ, Key Lab Green Bldg & Intelligent Construction High, Yiyang 413000, Peoples R China.;[Zhang, Xuhui] Xiangtan Univ, Sch Civil Engn & Mech, Xiangtan 411105, Peoples R China.
通讯机构：
[Yang, YM ] H;Hunan City Univ, Sch Civil Engn, Yiyang 413000, Peoples R China.
关键词：
bridge construction;anchoring failure;residual prestress;secondary transfer;experimental study
摘要：
To understand the secondary transfer performances of residual prestress after the anchoring failure of end-anchored steel wire strands due to corrosion fracture, six steel wire strand components of post-tensioning prestress were designed and fabricated. One-side fast corrosion was applied to the steel wire strand components using the electrochemical method until anchoring failure was reached. The sphere of influence, stress changes, and the retraction and swelling effect of broken beams after failure were investigated. The influences of factors such as concrete strength, stirrup area, and the length of the component on the secondary transfer length of residual prestress were discussed. Based on the deformation relationship between prestressed steel wire strands and concrete in the stress transfer zone, a stress equation was established and solved through a bond constitutive model. A prediction model of the effective stress transfer length of prestressed steel wire strand after failure was proposed. The results demonstrated that residual prestress can have a secondary transfer after the corrosion fracture of end-anchored steel wire strands, but some effective prestress may be lost. Moreover, the loss of prestress is inversely proportional to concrete compressive strength. When the specimens are relatively short, the prestress loss increases significantly. Concrete strength has significant influences on the length of secondary transfer. The proposed simplified calculation method of the secondary transfer length of residual prestress has a relatively high accuracy, with an average error of 2.9% and a maximum error of 5.2%.
摘要：
According to the current standards for prefabricated buildings, the dimensional tolerances of components are usually determined by experience, lacking a theoretical basis. This work demonstrates the mathematical distribution of the dimensional deviations of precast concrete components by measuring their three-dimensional dimensions. Utilizing the Kolmogorov–Smirnov test, the cumulative distribution function of dimension deviations was evaluated. In response to the fact that the tolerance division principle of equal upper and lower tolerance thresholds for prefabricated components in existing standards does not match the distribution of actual measured deviations of the components, this paper proposed a method for determining the tolerance values of prefabricated components based on the process capability index. The association between the process capability index and the qualification rate was utilized to determine the process capability index at a specified guarantee rate, which, in turn, determines the tolerance threshold values for various components. The results indicate that the range of unqualified random variables for the dimensional geometric parameters of the prefabricated components did not show a significant difference, with all values between 0.99 and 1.02. The coefficients of geometric parameter variation were all less than 0.0061, and the component dimensional deviation adhered to the normal distribution. By linking the process capability index with the pass rate, a process capability index of 0.55 at a guarantee rate of 90% was determined, along with the tolerance for various components.
期刊：
International Journal of Critical Infrastructures,2022年18(2):128-147https://doi.org/10.1504/IJCIS.2022.123421 ISSN：1475-3219
通讯作者：
Yin, C.
作者机构：
1. College of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China;2. College of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China;3. School of Civil Engineering and Architecture, Nanchang University, Nanchang 330031, China;4. Key Laboratory of Earthquake Engineering and Engineering Vibration, China Earthquake Administration, Institute of Engineering Mechanics, Harbin 150080, China;5. Department of Construction Engineering, Dalian University of Technology, Liaoning 116024, China
通讯机构：
College of Civil Engineering, Hunan City University, Hunan, Yiyang, China
作者机构：
[Tang, Huang; Yang, Yiming] Hunan City Univ, Hunan Engn Res Ctr Struct Safety & Disaster Preve, Sch Civil Engn, Yiyang 413000, Peoples R China.;[Peng, Jianxin; Zhang, Jianren] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;[Liu, Peng] Cent South Univ, Sch Civil Engn, Changsha 410114, Peoples R China.
通讯机构：
[Yiming Yang; Peng Liu] A;[Jianxin Peng] S;Authors to whom correspondence should be addressed.<&wdkj&>School of Civil Engineering, Central South University, Changsha 410114, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>Hunan Engineering Research Center of Structural Safety and Disaster Prevention for Urban Underground Infrastucture, School of Civil Engineering, Hunan City University, Yiyang 413000, China<&wdkj&>School of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, China<&wdkj&>Authors to whom correspondence should be addressed.
关键词：
high performance concrete (HPC);chloride ion diffusion;mesoscopic simulation;fly ash;silica fume
通讯机构：
[Wenchao He] C;College of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, China
关键词：
Porous mixed media;Relative dielectric constant;Ground-penetrating radar;Time-energy density analysis of the wavelet;transform method;Quantitative identification
摘要：
Natural materials mostly consist of porous mixed media, the relative dielectric constant (RDC) of which is a variable. The RDC of measured materials is often simply estimated as a constant value for the purposes of ground -penetrating radar (GPR) detection, which is one of the reasons for the significant quantitative identification error of GPR results. Only by accurately measuring the RDC of porous mixed media to calibrate the electromagnetic wave velocity can accurate quantitative GPR identification results be obtained. However, the difficulty is how precisely to identify the feature points of GPR signal of the measured material. In this study, a model test was carried out in a laboratory setting on porous mixed media consisting of dry sand, dry loam, and limestone. A new method was then proposed to accurately measure the RDC of porous mixed media. On this basis, three stages of accurate measurements of GPR were proposed, namely, signal processing, wavelet analysis, and quantitative identification. Experimental results showed that the relative error rate between the measured value (5.555) and the theoretical value (7.250) of porous mixed media was 23.38%, and the relative error rate of the measured value obtained by the new method was reduced from 13.78% to 1.50% in respect of quantitative recognition of GPR. The proposed method offers both unique advantages in improving the detection accuracy of GPR and great market potential, especially for projects requiring the accuracy of non-destructive testing (NDT). In addition, this study also proposed potential methodological feasibility and research ideas for predicting the physical properties of measured materials by establishing sensitive regions within three-dimensional spaces in the future.
通讯机构：
[Zi-Jian Fan] S;School of Civil Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
In order to study the dynamic response characteristics of circular extended foundation of wind turbine in mountainous areas, a 1:10 scaled model test was carried out on the circular extended foundation of 2MW wind turbine, and the deformation characteristics of wind turbine foundation under random wind load were analyzed by ABAQUS numerical calculation. The results show that: (1) The wind turbine foundation has different stress types on the windward side and the leeward side. The components of the windward side foundation are subjected to tensile stress, while the components of the wind turbine leeward side foundation are subjected to compressive stress. (2) The strain of the foundation bolt, the strain of the foundation ring, and the strain of the foundation plate are within the allowable range of material deformation, but the relative deformation of the windward side and the leeward side is quite different. (3) The numerical calculation results of wind turbine foundation under strong wind load are compared with the failure results of scale model experiment, which shows that the overall overturning failure of foundation is a dynamic response mode of wind turbine foundation. In the design and construction, it is necessary to strengthen the research on the windward side and the leeward side and strengthen the anti-overturning design of the wind turbine expansion foundation.
作者机构：
School of Civil Engineering, Hunan City University, Yiyang, 413000, China;School of Civil Engineering, Changsha University of Science and Technology, Changsha, 410114, China;State Gird Yiyang Power Supply Company, Yiyang, 413000, China
通讯机构：
School of Civil Engineering, Changsha University of Science and Technology, Changsha, China
关键词：
Bond stress transfer;Corrosion;Deflection;Flexural strengthening;Reinforced concrete beam
