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.;[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：
bond performance;bridge engineering;corrosion fracture;numerical simulation;secondary anchorage
摘要：
In order to explore the secondary bond anchorage performance between prestressed tendons and concrete after the fracture of steel strands in post-tensioned, prestressed concrete (PPC) beams, a total of seven post-tensioned, prestressed concrete specimens with a size of 3 × 7ϕ15.2 mm were constructed firstly, and the steel strands at the anchorage end were subjected to corrosion fracture. Then, the pull-out test of the specimens was conducted to explore the secondary anchorage bond mechanism of the residual stress of prestressed tendons experiencing local fracture. Moreover, the influences of factors such as the embedded length, release-tensioning speed, concrete strength, and stirrup configuration on anchorage bond performance were analyzed. Finally, the test results were further verified via finite element analysis. The results show that the failure of pull-out specimens under different parameters can be divided into two types: bond anchorage failure induced by the entire pull-out of steel strands and material failure triggered by the rupture of steel strands. The bond anchorage failure mechanism between steel strands and the concrete was revealed by combining the failure characteristics and pull-out load-slippage relation curves. The bond strength between prestressed steel strands and concrete can be enhanced by increasing the embedded length of steel strands, elevating the concrete strength grade, and enlarging the diameter of stirrups so that the specimens are turned from bond anchorage failure into material failure.
作者机构：
[Zhou, Shuming; Yan, Donghuang] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;[Zhou, Shuming] Hunan City Univ, Sch Civil Engn, Yiyang, Peoples R China.
通讯机构：
[Shuming Zhou] S;School of Civil Engineering, Hunan City University, Yiyang 413000, China<&wdkj&>School of Civil Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
bridge engineering;reinforced-concrete beam;cracking;bearing capacity;finite element method
摘要：
Cracking is one of the main diseases of small- and medium-span reinforced concrete (RC) bridges. It is a key problem to determine the change in mechanical properties of RC beams after cracking in bridge-performance evaluation. The present study performs static loading tests on seven simply supported T-beams with different crack damage conditions. The influences of crack location, crack depth and steel-bar diameter at a prefabricated crack on the stress, deflection and crack distribution pattern of pre-cracked test beams are investigated. The failure mode and mechanism of pre-cracked beams are revealed. Based on the experimental results, a finite element model of a pre-cracked beam is developed and validated. Following this, a theoretical prediction method is proposed to calculate the ultimate load of pre-cracked RC beams. The results indicate that the direct damage to mid-span section size can significantly affect the stiffness of the RC beam. The local damage of the tensile steel section has insignificant influence on the overall stiffness of the beam. The stiffness degradation of the pre-cracked beam at the quarter span is smaller than that of the pre-cracked beam at mid-span. The strain of the T-beam section in the pre-cracked test conformed to the assumption of the flat section. The experimental observations are in good agreement with the theoretical predictions, which can provide a theoretical basis for the performance evaluation of existing RC beams.
通讯机构：
[Yang, YM ] H;Hunan City Univ, Coll Civil Engn, 158 Yinbindong Rd, Yiyang 413049, Peoples R China.
关键词：
Prestressed concrete structures;Bonding behavior;Corrosion of steel strands;Pull -out experiment;Empirical formula
摘要：
Degradation of bonding behavior due to chloride-induced corrosion of steel strands is critical for serviceability of prestressed concrete structures. In this paper, total thirty-one central and eccentric pull-out specimens were tested to study the effects of strand corrosion, combined with stirrups or position of steel strand on global force-slip response, bond strength and failure pattern. Experimental results show that the bond strength of the eccentric pull-out specimen without corrosion or slight corrosion is greater than that of the centrally loading ones, and the opposite is true once the corrosion rate reaches 6%. Stirrups in bonding specimens can effectively restrain the transverse deformation of concrete, and significantly improve the bond strength between corroded strand and concrete. As the corrosion rate of steel strand increases, the bond-slip curves of specimens with stirrups tend to be similar to those without stirrups. Compared with the corroded deformed bar, the degradation of bond behavior caused by deformed bar corrosion is more serious than that of steel strand corrosion. By considering the combined effects of steel strand corrosion, stirrups and position of steel strand, an empirical model is proposed to predict the bond strength between corroded steel strand and concrete with reasonable accuracy.
作者机构：
[Jiang, Changbo; Ma, Yuan; Jiang, CB; Li, Shanshan; Li, Chuannan] Changsha Univ Sci & Technol, Sch Hydraul Engn, Changsha 410114, Peoples R China.;[Li, Shanshan] Hunan City Univ, Coll Civil Engn, Yiyang 413002, Peoples R China.;[Jiang, Changbo; Ma, Yuan; Jiang, CB; Li, Chuannan] Key Lab Dongting Lake Aquat Ecoenvironm Control &, Changsha 410114, Peoples R China.
通讯机构：
[Jiang, CB ] C;Changsha Univ Sci & Technol, Sch Hydraul Engn, Changsha 410114, Peoples R China.;Key Lab Dongting Lake Aquat Ecoenvironm Control &, Changsha 410114, Peoples R China.
关键词：
spatiotemporal trend;hydroclimatic variables;the Dongting Lake basin
摘要：
The Dongting Lake basin, located in the middle Yangtze River region, has long been under the threat of climate change. However, there has been a lack of comprehensive analysis and research on the long-term trends and interactions among hydrometeorological factors within the region. To address this gap, this study collected data from 31 meteorological stations in the region and employed statistical analysis methods, including the non-parametric Mann-Kendall test, Sen's slope test, and cross-wavelet analysis. The results revealed significant increases in temperatures, especially in the spring season, while summer, winter, and annual rainfall also exhibited a significant increase. However, spring and autumn rainfall showed a non-significant decrease, and there was a clear decreasing trend in annual streamflow. Interestingly, evaporation demonstrated a significant increasing trend. The annual average temperature and annual runoff exhibited approximately negative correlations in the 6-10-year resonance period and positive correlations in the 4-6-year resonance period. There are significant positive resonance periods in the relationship between annual precipitation and annual runoff within the range of 0-12 years, indicating that precipitation has a substantial impact and serves as the primary source of runoff. Furthermore, there was a transition between "abundance" and "dry" periods in the annual runoff around 4 a, occurring before and after 1973 and 2005. The change points in annual precipitation and runoff were identified as 1993 and 1983.
摘要：
In the realm of geological and mineral exploration, remote sensing technology has emerged as a pivotal high-tech instrument. However, the effective interpretation of remote sensing images, especially in the context of heterogeneous data processing, noise, and the identification of fine granularity, remains a challenge. In this study, a novel method for the identification of mineral elements within remote sensing imagery was introduced. Firstly, a heterogeneous feature tensor migration technique anchored on the Coupled Heterogeneous Tucker Decomposition (CH-Tucker decomposition) was presented. Through this technique, multi-source remote sensing data were effectively processed and fused. Notably, associated data features from varying resolutions and angles were seamlessly coupled. Subsequently, an optical remote sensing image processing model founded on the RFDNet network was established. This model demonstrated robustness against noise data, thereby enabling the identification of mineral elements with a higher degree of granularity. The proposed methodology exhibited the capacity to extract mineral element information comprehensively and with remarkable accuracy. Thus, this research offers both valuable theoretical insights and practical evidence for furtherance in geological research and mineral element exploration.
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.
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.
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.
期刊：
TRAITEMENT DU SIGNAL,2023年40(3):1195-1202 ISSN：0765-0019
通讯作者：
Ding, XY
作者机构：
[Ding, Xingyu] Hunan City Univ, Sch Civil Engn, Yiyang 413000, Peoples R China.;[Hu, Wenjun] Yunnan Geol Environm Monitoring Inst, Kunming 650216, Peoples R China.
通讯机构：
[Ding, XY ] H;Hunan City Univ, Sch Civil Engn, Yiyang 413000, Peoples R China.
关键词：
machine vision deep learning geological;geological disaster monitoring geological disaster;geological disaster early warning;deep learning
摘要：
Geological disasters, characterized by their destructive nature, pose significant threats to both human life and ecological environments. The advent of remote sensing technology has rendered hyperspectral remote sensing images an integral data source in monitoring and predicting these phenomena. However, it is noted that minor variations and detailed nuances within the images are often overlooked by traditional computer vision and deep learning techniques. Furthermore, data imbalances during the training of deep learning models have been identified as a potential hindrance to optimal performance. Recognizing these issues and the inherent unpredictability of geological disasters, an innovative approach has been developed. This approach encapsulates an optical flow-based method for enhancing the edges of geological remote sensing images, an improved geological disaster monitoring model leveraging the Isolation Forest algorithm, and an efficient implementation strategy. The suggested methods present numerous advantages, including the acceleration of computations to augment real-time monitoring of geological disasters, an enhanced capacity for handling extensive data, an improved system stability and fault tolerance, and the preservation of fundamental strengths such as linear computational complexity, unsupervised learning, and non-parametric methodologies. By synthesizing these methodological improvements and advantages, a swift, efficient, and flexible strategy for enhancing the Isolation Forest model is put forth. This research supports the development of geological disaster monitoring and early warning systems grounded in computer vision and deep learning, presenting substantial technical aid for related tasks.
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.
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%.
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
关键词：
Ground-penetrating radar;Time-energy density analysis of wavelet transform method;Biorthogonal wavelet basis construction;Dielectric permittivity;Inhomogeneous media
摘要：
In the field of nondestructive inspection, ground-penetrating radar (GPR) is a widely used investigation tool, usually to evaluate quality and safety in structural engineering. However, its development has been limited due to differences in the dielectric constant in inhomogeneous media. In this study, a time-energy density analysis of wavelet transform (TEDAWT) method for GPR signal singularity recognition was proposed. In addition, a biorthogonal wavelet basis with high similarity to GPR signal waveform was innovatively constructed and added into the wavelet toolbox. A model experiment was conducted to validate the feasibility of inverse calculation of the permittivity of wet clay by the TEDAWT method. Results showed that this method offered the advantages of signal denoising, resolution improvement, singularity recognition in GPR signal processing. Subsequently, a basic flow chart was established, which could be used to inversely calculate the permittivity of inhomogeneous media, and be applied to the quantitative identification of the thickness of the reinforcement protective layer in an expressway tunnel. The calculation results showed that the inverse calculation value of reinforcement protection layer thickness was 3.74% lower than the average relative theoretical error value. That improved detection accuracy provided a new method to quantitatively identify inhomogeneous media by GPR.
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.
摘要：
Real-time monitoring is an effective approach of early warning for landslide problems of mine slope. Analysis and evaluation were generally carried out from the aspects of soil moisture, groundwater level and slope deformation in the recent years. The volumetric water content under different rainfall intensities has always been the hot topic of geotechnical research. A large number of studies have shown that the occurrence of landslide often after reaching the overall saturation state. In current research, the seepage deformation of mine slope based on quasisaturated volumetric water content was studied by cylinder experiment and model test. The collapse time of the rainfall-induced landslide will also be forecasted to give early warning. In addition, different rainfall intensities and unsaturated permeability coefficient will also be summarized in this study. The initial quasi-saturated volumetric water content determined in this paper varies with rainfall intensity and physical characteristics of the sample. For these relations, it is necessary to understand the appearance of initial quasi-saturated volume water content as a permeability problem in unsaturated soils. The results shown that when considering soil deformation, the relationship between initial quasi-saturation and deformation is not always the same trend. The results of this research can provide a certain reference for the seepage of unsaturated soil.
