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This study synthesized polydimethylsiloxane (PDMS)‐modified polyaspartate polyurea (PPPU) with different ratios, considering the practical performance requirements of underground water supply pipeline spray repair materials. The successful synthesis of PPPU was confirmed using Fourier transform infrared spectrometer (FTIR) spectroscopy. The influence of the ratio of the two components and the content of α,ω‐aminopropyl terminated polydimethylsiloxane (APT‐PDMS) on the drying time and tensile performance of PPPU coatings was evaluated. Based on this evaluation, a superior ratio for PPPU coatings was proposed. Subsequently, the bonding performance, hydrophobicity, and corrosion resistance of PPPU coatings at the superior ratio were tested. The results indicate that as the mass ratio of polyaspartic acid ester to hexamethylene diisocyanate trimer increases, both the drying time and tensile strength of the coating decrease. The addition of APT‐PDMS results in a decrease in the tensile strength of PPPU, but an increase in its elongation at break. The peak value of elongation at break is achieved when the APT‐PDMS content is 5%, making the PPPU2‐1‐5 coating the superior ratio for spray application on water supply pipelines. Through experiments, it was determined that the bonding strength of the PPPU2‐1‐5 coating with cement mortar under dry and humid conditions, static water contact angle (93.4°), and corrosion resistance performance are superior to those of the unmodified polyurea coating, demonstrating its application advantages. The conclusions drawn in this study provide a theoretical foundation for the practical engineering application of PPPU. [ABSTRACT FROM AUTHOR]

The mode and magnitude of the blast load are the main cause of damage to the structure. Most current studies have simplified the blast load into a bilinear form that differs greatly from the actual time history curve and is applied directly to the structure, avoiding the fluid–solid coupling interaction between the water fluid and the structure. The simplified blast load for near‐explosion or internal explosion will bring a big error to the calculation results. To quickly determine the load on the structure surface under the action of underwater near the explosion, this study studies the interaction between water hammer wave and structure through the verified full coupling model, and puts forward the explosion load distribution function on the square plate surface under the action of underwater explosion, and establishes a simplified prediction formula for the explosion load parameters (peak pressure and positive reflection impulse) at the center of the plate surface, using these formulas, a general method for constructing the explosion load at any point on the structural surface is proposed, which lays a foundation for subsequent structural damage and failure analysis. [ABSTRACT FROM AUTHOR]

Global warming has intensified the intensity of compound drought‐hot extremes (CDHEs), posing more severe impacts on human societies and ecosystems than individual extremes. The vulnerability of global terrestrial ecosystems under CDHEs, along with its key influencing factors, remains poorly understood. Based on multiple remote sensing data, we construct a Vine Copula model to appraise vegetation vulnerability under CDHEs, and attribute it to climatic and biotic factors for five different vegetation types. High vulnerability is detected in central and southern regions of North America, eastern and southern regions of South America, Southern Africa, northern and western Europe, and northern and eastern Australia. The drier the climate, the higher will be the vulnerability. Furthermore, biodiversity and biomass are key biotic factors influencing the vulnerability of various vegetation types, such that ecosystems with richer biodiversity and higher biomass have lower vulnerability to CDHEs. The findings deepen understanding of terrestrial ecosystem response to CDHEs. Plain Language Summary: Drought and hot‐related extremes often coincide or follow one another, known as compound drought‐hot extremes (CDHEs), adversely affecting various vegetation processes. Thus, investigating the response relationship between vegetation dynamics and CDHEs is critical for maintaining the sustainable development of ecosystems under the background of climate warming. High ecosystem vulnerability is detected in central and southern regions of North America, eastern and southern regions of South America, Southern Africa, northern and western Europe, and northern and eastern Australia. Climatic factors (precipitation, arid index, temperature, and radiation) dominate the vulnerability of all vegetation types. The drier the climate, the higher will be the vulnerability of vegetation to CDHEs. Furthermore, biodiversity and biomass are key biotic factors influencing the vulnerability. The results provide us with essential insights for managing and adapting terrestrial ecosystems against climate change and are of interest to a wide range of audiences, including but not limited to ecologists, hydrologists, and climatologists. Key Points: A framework is developed to estimate the vegetation vulnerability in response to compound drought‐hot extremes and attribute it to various factorsVegetation vulnerability is higher for grasses and shrubs than for evergreen and deciduous forestsVegetation vulnerability is both affected by climate and biotic factors, but climate factors are more dominant [ABSTRACT FROM AUTHOR]

Using pipe lines to rehabilitate concrete drainage pipes is a popular trenchless technique. In this paper, the concrete pipe and liner are equivalent to a symmetrical structural mechanics problem, and the mechanical solution of the composite structure is obtained using the force method. Subsequently, the analytical solutions are compared with the test and finite element results. The distribution law of axial force, bending moment, and shear force of the composite structure are obtained, and the circumferential strain law of the inner and outer surfaces of the host pipe is analyzed. Lastly, the influence of pipe diameter and liner thickness on the bearing capacity of the host pipe is examined. The results indicate that the axial and shear force distribution of the composite structure remains the same for different pipe diameters, as the distribution diagrams of shear and axial force along the circumferential direction coincide. While the elastic modulus and thickness of the liner have no effect on the internal force distribution of the composite structure, they do directly affect the stress state of the host pipe. Additionally, the bottom support causes abrupt changes in the bending moments and strains of the host pipe. [ABSTRACT FROM AUTHOR]

Regular detection of defects in drainage pipelines is crucial. However, some problems associated with pipeline defect detection, such as data scarcity and defect counting difficulty, need to be addressed. Therefore, a Transformer‐optimized generation, detection, and counting method for drainage‐pipeline defects was established in this paper. First, a generation network called Trans‐GAN‐Cla was developed for data augmentation. A classification network was trained to improve the quality of the generated images. Second, a detection and tracking model called Trans‐Det‐Tra was developed to track and count the number of defects. Third, the feature extraction capability of the proposed method was improved by leveraging Transformers. Compared with some well‐known convolutional neural network‐based methods, the proposed network achieved the best classification and detection accuracies of 87.2% and 87.57%, respectively. Furthermore, the F1 scores were 87.7% and 91.9%. Finally, two pieces of onsite videos were detected and tracked, and the numbers of misalignments and obstacles were accurately counted. The results indicate that the established Transformer‐optimized method can generate high‐quality images and realize the high‐accuracy detection and counting of drainage pipeline defects. [ABSTRACT FROM AUTHOR]

To better understand the changes in the atmospheric evaporative demand (AED) in the context of global warming, the anomaly contribution analysis is presented to estimate mid‐long term contributions of meteorological factors to the AED. The Pearson correlation coefficient (RP) between the total contribution (ψ) of meteorological factors and the relative variation (ϕ) of the AED, and the Sen's trend slope (βS) of (ϕ, ψ) scatters are used to evaluate the applicability of the method. The smaller the values of |1 − RP| and |1 − βS|, the more applicable the method is. To validate the method, the reference crop evapotranspiration is employed as a proxy for the AED. The multi‐year contribution analysis is used as a comparison approach, which can only investigate the dominant meteorological factors of the AED in long term. Moreover, the Huaihe River basin of China is taken as a case study. Results show that (a) the values of |1 − RP| and |1 − βS| in mid‐long term are less than 0.1 in most cases when applying the anomaly contribution analysis, and the mid‐long term contribution processes of meteorological factors to the AED are clearly demonstrated; and (b) the wind speed and sunshine hours are the two most dominant factors (the total absolute contribution exceeds 60%) in long term, but they are not always the dominant factors in mid‐long term (e.g., wind speed in summer, and sunshine hours in winter). Therefore, the anomaly contribution analysis is a reasonable and effective method, which can help to gain insights into the changes in the AED. Key Points: Anomaly contribution analysis can identify the dominant meteorological factorsAnomaly contribution analysis is better than multi‐year contribution analysisDominant meteorological factors may not be consistent across time scales [ABSTRACT FROM AUTHOR]

Polyurethane grouting materials are increasingly used in the non‐excavation rehabilitation of roadbeds. The compressive strength of roadbed rehabilitation polyurethane (RHPU) grouting materials is the key to achieving the desirable repair effect, whereas the constitutive model of RHPU grouting materials is not yet understood. Here, the mechanical properties of RHPU grouting materials under compression were experimentally investigated, followed by establishing the hyperfoam constitutive model. The variation laws of the critical parameters in the model with density were function fitted, and then the constitutive model was simplified as an equation of density as the single independent variable. The comparisons between the theoretical and experimental mechanical behavior of RHPU grouting materials were discussed to illustrate the applicability of the hyperfoam constitutive model. Results show that with the increasing density, both the yield strength (σ1), elastic modulus (E1), and secant modulus (Es) increases exponentially, and the Poisson's ratio (v) increases logarithmically. The maximum increase in σ1, E1, Es, and v are about 750%, 720%, 940%, and 50%, respectively. Compared to the effects of density on the mechanical properties, the effect of loading rate is much smaller, and the side length has no effect. For RHPU samples with a density not exceeding 0.35 g/cm3, the hyperfoam model can well describe the uniaxial compression mechanical behavior, but for those whose density exceeds 0.35 g/cm3, the model can only describe the mechanical behavior before yielding. The theoretical yield strength of the RHPU samples obtained from the model is close to the experimental value (with differences of about 0.1%–14.4%). This study provides a base to evaluate the compressive strength of the practically used RHPU grouting materials based on the density. [ABSTRACT FROM AUTHOR]

Under the coupling effect of the defects inside and around pipes, the shear displacement of the joints of old concrete pipes fallen into disrepair usually shows an accelerated deterioration trend, and its excessive value can lead to structural damage or fluid leakage. Therefore, developing a prediction model for the maximum shear displacement of concrete drainage pipe joints with preexisting defects is of crucial significance. To this end, this work selects internal corrosion and erosion voids as the typical defects inside and around old pipes, establishes 300 sets of three‐dimensional fine finite element (FE) models of the concrete drainage pipes with corrosion and void, and verifies the reliability of the developed FE model by the full‐scale tests. Based on the verified FE data, a prediction model is successfully proposed for the assessment of the maximum shear displacement of the concrete drainage pipe joints with corrosion and void defects. Moreover, parameter sensitivity analysis is carried out to reveal their relative contribution to the maximum shear displacement of pipe joints. The results show that the model proposed herein has the ability to accurately predict the maximum shear displacement of the pipe joints. The maximum and minimum relative error between the value predicted by the proposed model and the one computed by the FE model is also 12.4% and 4.8% respectively. Moreover, the traffic load with a contribution of 28.7% has the greatest impact on the maximum shear displacement of pipe joints. [ABSTRACT FROM AUTHOR]

The cover image is based on the Research Article Mechanical response of concrete pipe rehabilitated by liner under external load: Analytical solution by Kejie Zhai et al., https://doi.org/10.1002/nag.3664..By Kejie Zhai; Hongyuan Fang; Niannian Wang; Bin Li; Jiaxiu Dong and Binghan XueReported by Author; Author; Author; Author; Author; Author [Extracted from the article]

Prestressed concrete cylinder pipe (PCCP) is widely used in hydraulic engineering. The bell‐and‐spigot joint is a weak point along a PCCP pipeline, since damage of joint can affect the operation of the whole pipeline. In this paper, a three‐dimensional numerical model of buried PCCP, considering the simulation of rubber gasket in bell‐and‐spigot joint is established. The fluid–structure coupling of PCCP is accomplished using the Mesh‐based parallel Code Coupling Interface (MpCCI), where the pipe and the surrounding soil are characterized in the software ABAQUS, and the pressurized water is modeled in the software FLUENT. The force and rotation angle at joints of PCCP under different conditions, including surcharge load, loading location, cover depth, and internal pressure, are analyzed. It is shown that the rotation angle of joint exceeds the allowable value, when the surcharge load is greater than 180 kPa. Compared with the effect of surcharge load, the offset distance (i.e., distance between the loading position and the pipe axis) has a greater influence on the development of horizontal displacement and rotation angle. As the offset distance increases, both the horizontal displacement and rotation angle at joints increase first, and they decrease after the peak. [ABSTRACT FROM AUTHOR]

The study of dynamic soil‐structure interaction is significant to civil engineering applications, such as machine foundation vibration, traffic‐induced vibration, and seismic dynamic response. The scaled boundary finite element method (SBFEM) is a semi‐analytical algorithm, which is used to solve the dynamic response of a three‐dimensional infinite soil. It can automatically satisfy the radiation boundary condition at infinity. Based on the dynamic stiffness matrix equation obtained by the modified SBFEM, a continued fraction algorithm is proposed to solve the dynamic stiffness matrix of layered soil in the frequency‐domain. Then, the SBFEM was coupled with the finite element method (FEM) at the interface to solve the dynamic stiffness matrices of the rigid surface/buried foundation. Finally, the mixed‐variable algorithm was used to solve the three‐dimensional transient dynamic response of the foundation in the time domain. Numerical examples were performed to verify the accuracy of the proposed algorithm in solving the dynamic stiffness matrix of the infinite domain in the frequency domain and the dynamic transient displacement response of the foundation in the time domain. Compared with the previous numerical integration technique, the dynamic stiffness matrix in the frequency domain calculated by using the proposed algorithm has higher accuracy and higher efficiency. [ABSTRACT FROM AUTHOR]

Fluctuations in the groundwater level make the working conditions of concrete pipes below the groundwater level more complex than those of concrete pipes above the groundwater level. This paper describes the application of a three‐dimensional (3‐D) refined finite element (FE) model to the analysis of a buried concrete pipe subjected to the coupled effects of traffic load and groundwater level fluctuations. First, the dynamic responses of the concrete pipes buried in dry soil were investigated with a full‐scale test and an FE model. The results show that the FE model predicted results similar to those observed in field pipes. Then, the dynamic responses based on the numerical results of pipes buried in dry soil under a traffic load and those of pipes buried in saturated soil under the coupled effects of a traffic load and groundwater level fluctuations were compared. Finally, a parametric analysis of the effects of the void ratio, permeability coefficient, and fluctuation period in the groundwater level in relation to the dynamic responses of the pipes was conducted. The results show that the mechanical behaviors of the pipes in dry soil were substantially different from those of pipes in saturated soil. Compared with pipes in dry soil under a traffic load, the stresses at the crown, springline, and invert of the bell under the coupled effects of the traffic load and groundwater level fluctuations were lowered by 44.8%, 52.0%, and 50.3%, respectively, while those of the spigot were lowered by 42.0%, 50.3%, and 49.6%, respectively. The maximum principal stress and the vertical displacement were proportional to the void ratio and the permeability coefficient, while their relationship to the groundwater level fluctuation period was less straightforward. [ABSTRACT FROM AUTHOR]

Existing deep learning‐based defect inspection results on images lack depth information to fully demonstrate the sewer, despite their high accuracy. To address this limitation, a novel attention‐optimized three‐dimensional (3D) segmentation and reconstruction system for sewer pipelines is presented. First, a real‐time sewer segmentation method called AM‐Pipe‐SegNet is developed to inspect defects (i.e., misalignment, obstacle, and fracture) efficiently. Attention mechanisms (AMs) are introduced to improve the performance of segmentation. Second, an attention‐optimized and sparse‐initialized depth estimation network called AM‐Pipe‐DepNet is presented to generate depth maps from multi‐view images. Third, a 2D‐to‐3D mapping algorithm is proposed to remove noise and transform the sewer segmentation results into 3D spaces. Comparison experiments reveal that incorporating AMs into the network significantly enhances pipe segmentation and 3D reconstruction performance. Finally, two digital replicas of real sewer pipes are built based on photos taken by probes, providing valuable insights for sewer maintenance. [ABSTRACT FROM AUTHOR]

Inversion of ground‐penetrating radar signals requires accurate and efficient forward modelling. The symplectic Euler method promises good results when simulating ground‐penetrating radar wave propagation in substructures, but its computational efficiency is limited by the same Courant–Friedrichs–Lewy stability condition as the finite‐difference time‐domain method. A two‐dimensional graphics processor unit–accelerated parallel symplectic Euler algorithm is used to simulate ground‐penetrating radar wave propagation. We compared the reflection waveforms as well as the simulation time of the complex underground structure models simulated by the parallel symplectic Euler method with traditional finite‐difference time‐domain method. Results show that the parallel symplectic Euler algorithm achieves the same level of accuracy as the standard finite‐difference time‐domain method. Moreover, it significantly improves the computational efficiency, as the calculation speed is improved by more than 21 times. We verify the performance of the proposed algorithm through a map of the single‐track radar data for a three‐layered pavement model and a simulation wiggle map for a structural damage pavement model. This provides a theoretical basis for accurately interpreting ground‐penetrating radar detection data and efficient forward modelling for the next step of inversion imaging. [ABSTRACT FROM AUTHOR]