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Current research has shown a nonlinear trend in the failure of soil, and the single tangent method is commonly adopted when coping with nonlinear problems of soil failure. However, the method equates a nonlinear criterion to an optimizable linear criterion, which may differ from the actual situation, resulting in conservative results. In this paper, two types of piece-wise log-spiral failure mechanisms for bearing capacity estimations, including symmetrical and unilateral mechanisms were proposed with the nonlinear Mohr-Coulomb criterion. The static bearing capacity of foundations was evaluated using the symmetric failure mechanism, while the seismic bearing capacity of foundations was evaluated adopting a modified pseudo-dynamic method based on the unilateral failure mechanism. The result shows that the bearing capacity calculated in the paper is smaller compared to the result using the linear Mohr-Coulomb criterion. For London clay, the static bearing capacity is reduced by about 45% at a foundation width equal to 1m. From the comparisons, it is found that the proposed approach of piece-wise log-spiral failure mechanism for bearing capacity estimation is effective. In addition, parametric studies show that the nonlinear parameters, the initial factor of seismic acceleration, the normalized frequency, and the damping ratio all have obvious effects on the seismic bearing capacity. A significant reduction in the seismic bearing capacity of the foundation occurs when the normalized frequency ωsH/Vs is equal to (0.5 + n)π (n = 0, 1, 2, ...). Considering that the approach proposed provides a strict upper bound to the bearing capacity, the result imparts confidence in the approach of analysis presented. [ABSTRACT FROM AUTHOR]

The complex three-dimensional (3D) finite element analysis of prefabricated vertical drains (PVDs) still has some problems, such as intricate modeling and expensive computational efforts. This paper aims to propose a modeling method to solve these problems. The traditional drainage substructural method without modification is relatively low in computational accuracy when used for 3D finite element analysis of PVDs. This paper proposes a modified substructure method suitable for 3D finite element analysis of PVDs under vacuum pressure. This method corrects the horizontal permeability coefficient of the soil in the smeared area and proposes a specific correction formula. The modified substructure method is verified from the unit cell 3D finite element model (FEM) and the multi-well 3D FEM. The results of the unit cell 3D FEM are compared with the axisymmetric analytical solution. The settlement results of multi-drain 3D FEM are validated with the field data of Tianjin Port case. The modified substructure with rectangular equipotential line can reduce the number of nodes of 3D FEM to 1/3 − 2/3 under relatively high calculation accuracy; the modeling process is relatively simple; reflect the actual situation of PVDs better. A new modeling choice is presented to conduct the complex 3D finite element analysis of PVDs. [ABSTRACT FROM AUTHOR]

The defect detection in the urban underground utility tunnel faces the challenges of low illuminance and large shadow region. The images collected have problems such as noise and uneven illumination, posing higher requirements for the image feature extraction ability of the network model. A residual feature pyramid attention network based on dense connections (RFPADNet) is proposed in the defect detection of the urban underground comprehensive pipe in this paper. The proposed network consists of three dense blocks, and each dense block uses four residual feature pyramid attention models (RFPAM) as the main feature extractors. Its focus is to utilize residual learning to obtain the fused multi-scale feature information. Soft mask branches are added to the multi-scale channels to enhance the network model's ability to extract positive features. The experimental results show that the network model proposed in this paper has a training accuracy of 97.50%. Compared with the existing network models, it could achieve better results in various test sets, which has good feasibility and practicality. [ABSTRACT FROM AUTHOR]

This paper aims to provide further elaboration on the main subject discussed in the recently published article titled "Experimental Study on Unconfined Compressive Strength of Rubberized Cemented Soil" in the KSCE Journal of Civil Engineering, authored by He et al. (2023). The intention here is to enhance the overall cohesion of the paper and render it more conducive to meaningful discussion. [ABSTRACT FROM AUTHOR]

This paper aims to establish an automatic and accurate pore identification method for pervious concrete. The residual module and mixed loss functions were introduced to the original UNet network to obtain the improved UNet. CT scanning was conducted on the six groups of pervious concrete samples with different aggregate sizes to obtain the initial dataset. The initial dataset was marked and enhanced, and then the pore recognition model was trained. The influence of image brightness and contrast on pore identification was analyzed. The fusion algorithm was used to improve the robustness of the model. The results show that during model training, R-UNet began to converge 20 epochs earlier than UNet and the loss value was smaller. Moreover, the maximum increase of mIoU and mDice was 10.3% and 11.7% respectively, and the maximum decrease of mHD was 14.1%. The fusion algorithm could improve the segmentation accuracy of pores in brightness anomaly images. Compared with threshold segmentation method, the method proposed in this paper could improve the accuracy of pore edge segmentation and the "fine pores" identification, and reduced the pore identification defects. The value of mHD was decreased by 48.7%–72.4%, and the efficiency of pore identification was greatly improved. [ABSTRACT FROM AUTHOR]

Suspension bridge is a flexible structure. The weight, location and number of traffic on the bridge will affect the geometric alignment of the bridge. Although the finite element software can analyze the geometric nonlinearity of the bridge, the calculation of random load combination in finite element software is huge. In this paper, based on the deformation coordination, static equilibrium and constitutive model of the bridge, the force expression considering the geometric nonlinearity of the bridge is derived. Finite element software is used to simulate the internal force of components of suspension bridge under train load and vehicle load. The accuracy is verified by comparing the finite element results. Considering the random number of traffics, the random location of traffics, and the random weight of traffics, this paper analyzes the stress state of bridge under the random process of train load and vehicle load respectively. The method in this paper can be well used to analyze the actual stress state of the bridge, and provide a theoretical basis for related calculations. [ABSTRACT FROM AUTHOR]

This bibliographic study presents a historical perspective on Korea's construction engineering and management (CEM) research and reports a 27-year analysis of papers written by Korean CEM researchers between 1993 and 2019. Frequency analysis of the collected papers was performed according to three main perspectives: the knowledge area, research topics, and methods. Knowledge area analysis shows that research fields have become more diversified and subdivided. Construction technology, cost management, and planning and schedule management have consistently maintained the top three positions for the past three decades. In addition, quality management, resource management, and risk management were also ranked high in the 2000s. In the 2010s, safety management, environmental management, quality management, and construction industry and business were ranked high. These changes reveal how Korean society's and industry's demands have changed over the years. Furthermore, the findings from keyword frequency analysis revealed that the focus of CEM research was mostly on cost and scheduling in the 1990s and on scheduling, risk, cost, and construction automation in the 2000s. The advent of Building Information Modeling (BIM) in the 2010s was an epochal change. This study found that the research methods frequently used by CEM researchers were simulation, optimization, regression analysis, computer vision and image processing, 3D modeling, case-based reasoning, genetic algorithm, case study, economic analysis, and artificial neural network. [ABSTRACT FROM AUTHOR]

Surrogate models have been proven to be reliable and effective methods for the application of engineering problems. This article presents a comparative study of three common surrogate models Polynomial Response Surface (PRS), Radial Basis Function (RBF) neural network, and Kriging model in terms of optimization. For the optimization of plane 10-bar truss structure and 25 bar space truss, the effectiveness of the surrogate model algorithm is verified by different surrogate models. Finally for a typical complex truss structure such as lattice boom of crawler crane, the Optimal Latin Hypercube Design (OLHD) is used to sample the optimized sample points for fitting and interpolation of three surrogate models and analyzing their errors, in order to get better surrogate effect, PRS is combined with RBF Neural Network, and secondly, the global optimization algorithm (Multi-Island Genetic Algorithm, MIGA) and gradient algorithm (Modified Method of Feasible Directions, MMFD) are used to optimize the fitted four surrogate models. Through the comparison of the optimization results, the optimization of PRS-RBF combined surrogate model using MIGA-MMFD algorithm instead of finite element model optimization has good stability and reliability. The total mass of the optimized model has been reduced by 24.47%. The number of optimization iterations is within 250 generations. The new method proposed in this paper can greatly promote the reduction of the period of analysis and optimization of engineering structures. [ABSTRACT FROM AUTHOR]

Virtual reality (VR) has been widely used in education and training, but few studies have used it in education on construction site planning. Accordingly, this study developed an immersive VR-based education system for construction site planning and evaluated it in classroom-based tests with 114 students. Statistical analyses revealed that the VR system improved students' learning outcomes compared when conventional paper-based learning. Specifically, students with lower pretest subject knowledge achieved similar scores to top-ranked students after undergoing VR education. Moreover, VR education was more effective for learning concepts than it was for memorization. A single-source teaching approach was also more effective in improving learning outcomes than a multisource approach for VR learning. In summary, this study investigated three previously unexplored areas: targeting the ideal recipients for VR education and training, determining the appropriate problem types for VR education and training, and identifying the effectiveness of VR education and training for construction site planning. [ABSTRACT FROM AUTHOR]

Cracks are important indexes to evaluate the health status of concrete structures. To accurately and automatically identify the cracks of concrete structures, and solve the time-consuming and labor-intensive limits of manual detection methods, this paper proposed an image-based concrete cracks identification method based on a lightweight Convolutional Neural Network, which includes three modules: crack classification, semantic segmentation and quantitative calculation of crack geometric size. Firstly, the S_MobileNet was used to classify cracks, exclude irrelevant regions, and reduce the interference of non-crack images; Secondly, the optimized method SM-UNet based on the U-Net network was employed to segment the detected crack image at the pixel level; Finally, based on the results of crack semantic segmentation, image post-processing technology was used to realize the quantitative calculation of crack geometric size parameters, which provides a basis for crack damage assessment of concrete structures. The experimental results show that this study provides a solution for the automatic detection of crack images and high-precision measurement of crack size, which has an important value in scientific research and engineering application. [ABSTRACT FROM AUTHOR]

As the main structural bodies of underground facilities such as subway stations, frame tunnel structures play an important role in urban development and construction. In recent years, with the frequent occurrence of explosions after vehicle impacts in tunnels, which have caused severe damage to frame tunnels, the lack of relevant papers makes it necessary to develop a dynamic response analysis of frame tunnels. In this paper, by optimizing the design of an original frame tunnel structure, a dynamic response numerical model of the frame tunnel considering the impact effect of a 3D solidified vehicle and the joint effect is investigated. The deformation trend and damage evolution of the frame tunnel are analysed under different collision masses (1.4, 2.4, 6 and 15 t), collision angles (5, 10, 15 and 75°), collision speeds (60, 80 and 100 km/h), blast delay times (10, 20 and 30 ms) and blast equivalents (50, 100 and 200 kg TNT). This paper improves the active and passive robustness of frame tunnels using both improved operational management and the optimal design of the tunnel structure as a way to ensure the structural safety and functional resilience of frame tunnels. [ABSTRACT FROM AUTHOR]

Korea implemented a truck safety fare system for a trial period from January 1, 2020 to December 31, 2022, to improve the safety of truck drivers through fare regulations. However, if changes in freight transport volume due to the introduction of the system can be identified from changes in rail transport performance, it is possible to estimate the elasticity of substitution between road transport and rail transport. This paper presents a double-difference model to analyze how the difference in transport performance by train between freight types has changed before and after the implementation of the system. The analysis results indicate that the system had indeed the effect of converting freight transport volume from road to rail. [ABSTRACT FROM AUTHOR]

RC structures are usually large, and it is arduous to use test methods to accurately analyse the redistribution of internal forces and development of plastic hinges during fires. This paper proposes a method for judging the formation and development of plastic hinges in the cross-sections of reinforced concrete structures under thermo-mechanical coupling effects. Using this method, the damage patterns of reinforced concrete structures under high temperatures are preliminarily studied. For reinforced concrete structures, the most severely damaged components during a fire may not necessarily be those on the floors exposed to the fire. For structural components on other floors, even if they remain at ambient temperature during the fire, the internal forces within them may undergo drastic changes due to the redistribution of internal forces throughout the structure. This can lead to reaching the yield limit or even the ultimate limit state, severely impacting the overall structural safety. [ABSTRACT FROM AUTHOR]

In order for the progression band to be effective, the convoy must travel at the fixed green band speed. However, due to the objective influence of uncertain factors, it's difficult for vehicles to drive at the green band speed, especially on the arterials, which have multiple important path flows in different directions. Due to the entanglement of path flows in different directions in the arterial segment, the operational interference between vehicles will increase. As a result, the speed of vehicles will inevitably fluctuate, which greatly weakens the control effect of arterial coordinated signal control methods. In order to improve the green bandwidth utilization efficiency, this paper proposes a multi-path arterial signal coordination control method that considers the speed uncertainty. The results of extensive simulation studies show that the proposed model outperforms other methods in terms of overall arterial performance, intersection performance and path performance. And the signal timing generated by the proposed model shows promise in reducing travel delays and stopping times, which indicates that it can achieve better multipath progression effect. [ABSTRACT FROM AUTHOR]

The slime mould algorithm (SMA), a revolutionary metaheuristic algorithm with streamlined operations and processes, is frequently utilized to solve optimization issues in various fields. This paper proposed a modified slime mold method (HKTSMA) based on multiple adaptive strategies to ameliorate the convergence speed and capacity to escape local optima. In HKTSMA, the scrambled Halton sequence was utilized to increase population uniformity. By Adjusting the oscillation factor, HKTSMA performs better in controlling the step length and convergence. A novel learning mechanism was proposed based on the k-nearest neighbor clustering method that significantly improved the convergence speed, accuracy, and stability. Then, to increase the probability of escaping the local optima, an enhanced adaptive t-distribution mutation strategy was applied. Simulation experiments were conducted with 32 test functions chosen from 23 commonly used benchmark functions, CEC2019 and CEC2021 test suite and 3 real-world optimization problems. The results demonstrated the effectiveness of each strategy, the superior optimization performance among different optimization algorithms in solving high-dimensional problems and application potential in real-world optimization problems. [ABSTRACT FROM AUTHOR]

Addressing the challenge of large deformation in soft rock tunnels is an urgent imperative. The conventional support method is mainly passive or low-stress compensation support, which proves inadequate in effectively managing the large deformation disaster of soft rock under complex geological conditions. This paper focuses on three representative soft rock tunnel scenarios characterized by slate, schist, and metamorphic rock lithologies. The primary objective is to conduct a comprehensive comparative analysis of the efficacy of the NPR (negative Poisson's ratio effect) anchor cable high preload support system based on the excavation compensation method. The results indicate that the NPR high preload support method adeptly controls large deformation disasters in soft rock, maintaining tunnel surrounding rock deformation within 300 mm (<3%). To achieve efficient high-stress compensation through high preload, supporting technologies should be designed for different geological conditions, exemplified by the implementation of double-gradient grouting technology in the Tabaiyi tunnel. This paper comprehensively validates the effectiveness of the NPR high preload support method in mitigating large deformations in soft rock and establishes a foundation for future engineering endeavors. [ABSTRACT FROM AUTHOR]

Swift and precise classification of rock masses significantly enhances the prudent and efficient advancement of rock mass engineering. To expeditiously and accurately determine the engineering classification of slope rock masses, this paper introduces a hybrid Data Comprehensive Weight Analysis (DCWA)-Equilibrium Optimizer (EO)-AdaBoost ensemble prediction model. This model is formulated to prognosticate revised Basic Quality value ([BQ]) and the engineering classification of slope rock masses, utilizing the Basic Quality (BQ) classification method. Six elements have been chosen to formulate the prognostic index, and a dataset comprising information on the slope rock mass of 266 groups has been assembled for the purpose of training and evaluating the predictive accuracy of the established model. Two slope sections in DEZIWA open pit mine is chosen to validate the correctness of established DCWA-EO-AdaBoost model in the field through numerical simulation. In comparison to AdaBoost, DCWA-AdaBoost, DCWA-EO-AdaBoost, K-Nearest Neighbor (KNN), Back Propagation (BP), Decision Tree (DT), and Random Forest (RF) models, it is discerned that the DCWA-EO-AdaBoost hybrid model exhibits elevated coefficient of determination (R2, 0.986), variance accounted for (VA, 98.64%), prediction accuracy (A, 92.31%), and kappa coefficient (KC, 88.87%). Conversely, the mean absolute error (E, 5.97%) and root mean square error (ER, 38.37) are diminished, affirming its reliability and superiority. Field validation reveals that, combine the DCWA-EO-AdaBoost model and BQ classification method, mechanical parameters used for slope stability analysis can be obtained accurately, and can obtains slope stability analysis results basically consistent with the engineering practice through numerical simulation, which can prove the correctness of the established prediction model and clarify the use of the established model in the process of slope stability analysis. This attests that the established predictive model holds substantial merit, offering a noteworthy reference for the expeditious and precise acquisition of [BQ] and the classification of slope rock mass based on the BQ method, and can be adopted in the process of slope stability analysis. [ABSTRACT FROM AUTHOR]

Sliding damage of canal slopes due to the degradation of shear and compression properties of expansive soils caused by long-term dry-wet-freeze-thaw cycles is frequently encountered in canal projects in cold and arid regions. To address this issue, this paper developed a new reinforcing technique for expansive soil canal slopes with monolithic structural anti-slide piles. The sliding damage mechanism of the canal and the reinforcement schemes were analyzed based on the numerical simulations with the FLAC 3D software. The results showed that force redistribution of double-row piles occurred under the longitudinal connection. The maximum reduction in pile displacement was 20.66% under the X-type connection, and the distribution of internal force of pile body changed. The pile forces were redistributed again under the full connection mode, and the pile displacement increased by 4.38%, 95.14%, and 82.09% under the transverse and longitudinal connection mode, the front and rear full connection mode, and the frame full connection mode, respectively. The stability of the canal slope returned to a steady state (FS > 1.30) in the full connection mode. The findings in this paper can provide guidance for practical engineering. [ABSTRACT FROM AUTHOR]

Analysing bus travel time is essential for providing valuable information to users for effective journey planning. This study aimed to analyse bus travel time in Klang Valley, Malaysia, which includes the urban centre of Kuala Lumpur as well as the surrounding suburban areas. A two-part study is presented here. The findings on superiority of proposed mixture model, namely the Burr XII mixture model as a new statistical distribution to fit travel time distribution based on day-to-day variability under spatial (number of signalized intersections, link length, route type) and temporal aggregation (15 minutes aggregated, peak/non-peak period) are validated in the previous publication. Based on the results, the study was deepened to analyse the effects of some factors on travel time variability. As an extension, factors and indicators influencing multimodality travel time patterns on all the bus sections are examined in this paper. This research explores the impact of several factors outlining the usage of Burr XII mixture regression model, particularly the quantile regression analysis on three distinct routes, each exhibiting unique characteristics, originating from both suburban and urban areas. The results have demonstrated that the factors vary depending on the time of day and coverage area. By gaining an understanding of and effectively addressing the crucial elements that influence travel time, the overall effectiveness of bus systems can be enhanced. [ABSTRACT FROM AUTHOR]

53.5% of China's territory is seasonally frozen. Along with China's fast social and economic development, more and more infrastructure facilities, e.g., railways, highways and hydraulic engineering projects, are being constructed in frozen soil areas. Since foundations are the underpinnings of these engineered structures, the performance of frozen soil foundations is critical to the safe and stable operation of these infrastructures. Frozen soil exhibits strong heterogeneity, which influences the prediction of the engineering performance of frozen soil foundations; however, previous studies have ignored this effect. In this paper, the coupling effect of thermal and hydraulic behavior and soil parameter heterogeneity of frozen soils is considered. A rectangular foundation is taken as an illustrative example, and COMSOL Multiphysics is applied to predict the coupled thermal and hydraulic behavior of frozen soil. Karhunen-Loève expansion is selected to capture the frozen soil parameters' heterogeneity. Based on the analysis, the proposed framework can successfully calculate the stochastic frozen depth of the foundation. Due to the thermal conductivity's heterogeneity of soil grains, the depth to which the foundation is frozen changes in a range rather than a single value in the deterministic analysis. [ABSTRACT FROM AUTHOR]

Reinforcement treatment for the damaged structure can guarantee the continued safe use of the building. This paper proposes a new prestressed column reinforcement technology for traditional steel structure reinforcement technology by using space profile steel structure instead of angle steel and combining prestressing technology and bolt connection. According to different constraint forms, 4 types of members were designed, and the eccentric compression test and finite element parameter analysis were carried out. The experimental study found that, after being reinforced by prestressed lattice steel, the ultimate load-carrying capacity of the specimen was increased by 49.2%, stiffness by 28%, and deformation capacity by 15%. Compared with the traditional angle steel reinforcement, the reinforcement effect is improved by more than 20% under the same cross-section steel consumption condition. Prestressing can significantly improve the utilization of steel, and steel strain increases by about 30%. At the same time, applying prestressing can improve the stress state of the concrete and steel rebar of the core column. The various parts of the reinforced specimen work together better, and the integrity is enhanced. Based on the test, a parametric analysis was carried out, mainly considering the effects of material strength, eccentricity and steel plate thickness. It was found that increasing the thickness of lattice steel can effectively improve the specimen bearing capacity and ductility, and the strength ratio of reinforcement to lattice steel is about 0.16. However, increasing the strength of steel does not have a significant effect on the bearing capacity. The deformation capacity occurs to be reduced, and using high-strength steel is not recommended. By applying prestressing, stronger restraint can be provided to the reinforced columns, and the reinforcement effect is significantly better than that of angles, which has better engineering application value. [ABSTRACT FROM AUTHOR]

In this paper, self-piercing riveting (SPR) is implemented to thin-walled cold-formed steel and concrete (CFSC) composite structures for the first time. Tensile comparison tests were conducted on 5 groups of composite joints and 1 group of SPR joints. The load-displacement curves, ultimate loads, and failure modes were analyzed according to the experimental results. The parameters of the concrete strength, sheet thickness ratio, and sheet combination type were studied to determine their effects on the tensile performance of the composite joints. Numerical simulations were performed with ABAQUS software to verify and analyze the damage behavior of the composite joints. Based on models of the SPR joint and the force transfer mechanism, a method for determining the tensile capacity of the composite joint was proposed. The results of the tests show that concrete restraints can limit the buckling of the sheet and rivet tilting, significantly increasing the ultimate tensile capacity of the composite joints. The concrete strength, sheet thickness ratio, and sheet combination type were important factors affecting the tensile strength of the composite joints. Moreover, a new method for calculating the tensile strength of composite joints is proposed in this paper. In addition to being accurate, this method can be used to consider the effects of concrete constraints. [ABSTRACT FROM AUTHOR]

This paper presents the hydraulic and structural design of a hydraulic jump stilling basin over a rough bed using three-dimensional, unsteady, detached-eddy simulation (DES). The concept design is related to a stilling basin downstream of a 50 m high dam. The use of a rough bed reduces the stilling basin length and depth, compared to the smooth bed scenario, avoiding the use of baffle blocks or dentated sills as suggested in the literature and guidelines, such as U.S. Bureau of Reclamation (USBR). The aim of this paper is to extend recent theoretical analysis on hydraulic jump over a rough bed to real-life dam cases and compare the result with the classical smooth bed stilling basins. The information related to the application of Computational Fluid Dynamics (CFD) to hydraulic jump stilling basins over rough beds is limited, and this paper provides novel results on the internal characteristics of the hydraulic jump over rough beds as well pressure fluctuations coefficients, spatial correlation function, and coefficient of lift. The CFD results are validated using available experimental and theoretical information. A step-by-step guide is also included demonstrating the structural and hydraulic design of a hydraulic jump stilling basins over a rough bed. [ABSTRACT FROM AUTHOR]

Recycled aggregate concrete is an effective solution for efficiently managing municipal construction waste on a large scale. Shear bearing capacity (SBC) is significant for reinforced concrete structures, and it is essential to develop trustworthy calculation models for structural design. This paper proposes a tree model-based SBC assessment system that considers eight design parameters of reinforced recycled concrete beams (RRCBs). Evaluation results revealed that the extreme gradient boosting model yielded the highest prediction accuracy with an R2 of 0.960 and a mean absolute percentage error of 7.343%. To reduce the risk of black-box models, this study conducted feature importance calculations, sensitivity analyses and reliability validation of the prediction results. The findings demonstrated that increasing the hoop reinforcement ratio and beam width significantly improved the SBC of RRCB. The compressive strength and longitudinal reinforcement ratio had positive effects on the SBC, while longitudinal steel bar yield strength had no effect on the SBC. These analyses can be combined with physical mechanisms to better refine the performance design. Furthermore, a comparative study utilizing two commonly used standard formulas was conducted. The results indicated that the SBCs estimated using the tree model are more accurate than those calculated by the standard formulas. [ABSTRACT FROM AUTHOR]

In this paper, model updating for tall tower structures is discussed, a novel model variable index is proposed, and a selection method of model variables to be updated that can consider the high sensitivity of the displacement residuals and the small influence of the measurement errors is presented based on an artificial neural network (ANN). When the multi-layer perceptron architecture of the ANN obtains the optimal number of hidden layer neurons and the number of iterations, it is verified that the position and degree of the structural model defects can be detected by updating the selected model variables. Additionally, situations in which there is a large order-of-magnitude difference between the model variables are also discussed. It is found that in the proposed model variable index, the displacement residuals are more important than the measurement errors; however, as the measurement errors increase, they become more important in the model variable index. Furthermore, when the large-scale structure is damaged, the dynamic model can be transformed into an equivalent static model. Based on these results and findings, the proposed approach is expected to be used for design and analysis purposes, including structural health monitoring, safety assessment, damage identification, and structural reinforcement. [ABSTRACT FROM AUTHOR]

This discussion article provides commenting on the sections of the review paper by Ahmad et al. (the authors) concerning consistency limits determinations for peats and peaty soils, drawing on the writer's experiences regarding the usefulness of liquid limit (LL) and plastic limit (PL) testing/results for these soils in explaining their geotechnical behaviors/properties. From the writer's experience, despite being regularly specified in geotechnical engineering practice and used in research work, the conventional consistency limits tests generally do not produce physically meaningful results when testing peat soils, especially for more fibrous peats. Hence, the writer does not agree with the authors' recommendations on consistency limits testing of peats; namely, they recommended that an utmost effort is needed to improve the quality and standard of the thread rolling test and the fall-cone test for consistency limits determinations of highly organic soils such as peat. Rather than grappling with various known inherent shortcomings of consistency limits testing for peats and other highly organic soils, a suggested way forward for assessing the likely geoengineering behavior/properties of these materials points to the routine measurement of a more useful suite of index tests; namely, their natural water content, organic content, fiber content, and humification (decomposition) level. In this discussion, the above aspects are explored in detail, including greater elaboration of the writer's earlier research work in this area, which was touched on in the authors' paper. [ABSTRACT FROM AUTHOR]

The complex construction process of the metro shield method often leads to safety accidents. The various construction stages of shield tunnel construction comprise different construction activities and are accompanied by different safety risk factors. However, traditional risk assessment often evaluates the risk factors as a whole before shield tunnel construction and does not evaluate the risk factors dynamically by construction stages and by construction activities. To fill this gap, this paper aims to construct a dynamic Bayesian-based safety risk assessment model for shield tunnel construction from the perspective of changing construction stages and activities. First, safety risk factors were identified using the work breakdown structure-risk breakdown structure (WBS-RBS) method. Then, a three-stage dynamic assessment model of safety risks was constructed to depict the shield launch, shield tunnel, and shield reach. The dynamic Bayesian network (DBN) was improved to address the model with triangular fuzzy numbers and the leaky noisy-or-gate extension model. Finally, a case study was conducted. The model proposed in this paper is able to reveal the dynamic evolution of safety risks triggered by different construction activities. It offers a new simulated model for the prevention of safety accidents in the construction of metro shields. [ABSTRACT FROM AUTHOR]

The stability of the rocky slope is a systematic problem under the combined action of many complex and changeable factors. In this paper, a comprehensive evaluation model based on VIKOR and binary semantics is proposed, and the stability of the rocky slope is predicted and evaluated. Fristly, according to the damage mechanism and the failure process of the slope rock mass, eight influence factors, such as rock cohesion, internal friction angle, and seismic intensity, are selected as the evaluation indexes for the rocky slope stability forecast. The rocky slope stability evaluation index system has been established. Secondly, a stability forecast model of the rocky slope based on VIKOR and the binary semantics method is proposed. The visualization window and the software system of the prediction model are realized by the Python 3.5 software. Finally, the software is applied to the stability evaluation of the rocky slopes, such as Jinping I Hydropower Station and Longtan Hydropower Station. The result shows that: 1) The visual window and the software operating system of the rocky slope stability forecast model, as well as the evaluation index system replacement button are realized, which improve the calculation efficiency of the sample data and the practicability and applicability of the software system. 2) The calculation results of the rocky slope stability prediction model based on VIKOR and the binary semantics method proposed in this paper are more consistent with the actual engineering situation, and more accurate than the prediction results obtained by other evaluation methods. 3) The proposed software system of the rocky slope stability is also suitable for other geotechnical engineering such as tunnels and coal mines, and which has a good prospect of the engineering application. [ABSTRACT FROM AUTHOR]

Instrumentation during tunnel construction can be used as reference data to identify anomalies, find the causes, and develop countermeasures through data trend analysis in terms of the construction, maintenance, and management of tunnels. Therefore, obtaining reliable and accurate data is very important to prevent large accidents and minimize damage. However, measurement sensors used in the field often show abnormal data because of the noise caused by functional and environmental factors. Such data may be misinterpreted as actual data caused by accidents in the analysis process and lead to construction delays due to investigating the situation. Moreover, the accumulation of such data may also have negative effects on analyzing the trend of the entire measurement data. Therefore, this paper proposes data filter-based correction techniques to correct noisy measurement data so that it does not affect the trend of accumulated data. By applying data filters of various sizes through simulations, this paper also presents the appropriate data filter size by examining the performance by filter size and validates the data correction performance by applying the proposed techniques to accumulated actual data measured from a construction site. [ABSTRACT FROM AUTHOR]

It is necessary to study the propagation path of cracks in concrete materials and its influence on the loading capacity of specimens. The phase-field method for fracture offers a distinct benefit in simulating the crack propagation behavior of brittle materials, which is achieved by implementing a phase field that continuously fluctuates to approximate the crack configuration, abolishing the need for mesh reconstruction and tracking the cracks. In this paper, we have implemented a phase field model using ABAQUS, whose reliability is verified through a tensile test. Then, the splitting test of Brazilian disc is simulated and the results are similar to those of the laboratory experiment. Furthermore, the crack configuration of the prefabricated cracked discs with different tilt angles and different initial lengths is explored. The two important parameters of the phase field method, Gc and l0, are discussed in the Discussion section. A larger Gc value means a larger material toughness and a larger failure load, and a larger l0 value means a larger crack smear range as well as a smaller failure load. [ABSTRACT FROM AUTHOR]

The ultimate load capacity of extradosed cable-stayed bridges (ECSB) is the basis for structural design and bridge management. The ECSB is a new combination system of both cable- stayed bridges (CSB) and multi-span continuous bridges. It is difficult to predict the ultimate load capacity of ECSB due to its particular form. In this paper, a novel method is presented to predict the ultimate load capacity of ECSB. The procedure of predicting ultimate load capacity consists of two steps. The first is that the ECSB can be equivalent to a multi-span continuous girder with the analogy method; The second is that structural configuration is developed when the live load can form the plastic hinge (PH) and it can determine the load locations using influence lines (IL). Finally, the proposed method is validated with other analytical solutions and numerical results. The results show that the proposed method agrees with previous research findings and the finite element method (FEM). It demonstrates that the proposed method can predict the ultimate load capacity of ECSB. [ABSTRACT FROM AUTHOR]

This paper proposes a novel approach for structural damage identification using the Salp Swarm Algorithm (SSA) combined with Orthogonal Diagonalization (OD). SSA is an optimization algorithm developed in recent years and has been considered for addressing complex and computationally expensive engineering problems. However, due to the utilization of only the leader salp to search for optimal solutions, there is an imbalance between the exploitation and exploration capabilities of the salp swarm. To address this issue, we suggest the use of OD to enhance the search capability of the leader salp. OD plays a crucial role in reducing the search space and selecting high-quality salp elements in subsequent iterations. From that idea, the algorithm is tested with 12 benchmark functions, and the results demonstrate superior convergence for all of these compared to the algorithm without OD. A comprehensive study with various damage scenarios is also conducted with the Cua Rao bridge. The outcomes indicate that the accuracy, with a deviation rate when using OD, is only 1.412%, whereas it is 2.224% for the SSA in the case of a single damage scenario. As the number of damaged elements increases, the error of SSA rises to 99.667% when identifying damaged elements, while errors using OD remain below 10%. Additionally, the computational speed is significantly enhanced by approximately 40% in both scenarios. [ABSTRACT FROM AUTHOR]

In this paper, factor of safety (FOS) considering three-dimensional (3D) and nonlinear shear strength of geomaterials is formulated based on the modified spatial mobilized plane (MSMP) model. The MSMP model has the desirable features of considering 3D strength and the nonlinear shear behavior of soils, compared with the widely used Mohr-Coulomb (M-C) model. The MSMP model is developed from the spatial mobilized plane model by relating the internal friction angle to the mean effective stress within the framework of critical state soil mechanics. Based on the developed MSMP model and the geometric relationships in the mobilized effective normal-shear stress plane, the nonlinear 3D FOS is defined as the ratio of mobilized shear strength to shear stress. The developed nonlinear 3D FOS is applied to slope parametric and case studies. The parametric studies show significant differences between the nonlinear 3D FOS by the MSMP model and the traditional linear two-dimensional (2D) FOS by the M-C model. The case study shows that the MSMP model and nonlinear 3D FOS can better capture the developed failure slope zone than the M-C model and linear 2D FOS. [ABSTRACT FROM AUTHOR]

A novel model is created in this paper to realize the systematic evaluation of the mechanical properties and construction safety of the pipe roof support system. The pipe roof is split into supported area, unloading area, and stable area based on the load distribution characteristics. Combining a statically indeterminate beam (for the area of unloading) with an elastic foundation beam (supported area and stability area) takes into account the mechanical effect of the pipe roof. The new model can better reflect the load transfer mechanism and the stability of the tunnel face under the pre-support. It is demonstrated that the novel model, when compared to the existing theoretical solution, is more closely related to the measured and simulated results than typical engineering cases and is practical for field application. It can provide a new idea for the design of pipe roof support and the safety evaluation of field construction. [ABSTRACT FROM AUTHOR]

Deep buried tunnel has a complex stress environment and large stress level. At present, it is difficult to dynamic monitoring for such tunnels. In order to make the safety evaluation and prediction of tunnel closer to the engineering practice, this paper deduces the tunnel reliability evaluation algorithm. The time-varying reliability of deep tunnel excavation process is analyzed and predicted. Based on the similarity theory, the actual deep tunnel excavation is simulated by indoor model test, the stress and deformation are monitored. The results show that after the tunnel excavation, the reliability of the structure does not decrease gradually, but increases slowly first and then decreases sharply. With the increase of the buried depth of the tunnel, the structural reliability decreases gradually. When the buried depth reaches a certain depth, the structural reliability will decrease rapidly. The influence of different parameters on the structural reliability has different sensitivity. The sensitivity of friction angle is the highest, and the sensitivity of gravity is the lowest. The sensitivity has little effect with the change of tunnel excavation time and tunnel buried depth. The accuracy of this method is verified by the comparative analysis of model box tests. [ABSTRACT FROM AUTHOR]

The deformation pattern of the stratum caused by constructing a new metro tunnel crossing an existing tunnel is different from the deformation pattern caused by general tunnel construction. However, the prediction results by the ordinary surface settlement prediction model often bring significant errors because the complex influence of existing tunnels on the surface settlement caused by the excavation of new tunnels is always neglected. Based on the equivalent layered method and stochastic medium theory, a prediction model for the surface settlement due to excavating a new tunnel under an existing tunnel in the heterogeneous stratum was established. By equating the bending stiffness of an existing tunnel before and after applying the equivalent layered method, the layer index was determined. The critical parameters of the stochastic medium theory were derived based on the relationship between the critical parameters of both the Peck empirical formula and the stochastic medium theory. The surface settlement of some typical projects was predicted and compared by the prediction model in this paper and the ordinary prediction model. The comparison shows that the proposed prediction model and parameter determination method in this paper had high accuracy and applicability. The results of the prediction model in this paper fit the results of numerical calculation. The research of this paper can provide a new method for the theoretical prediction of surface settlement caused by the excavation of a new tunnel under an existing tunnel in the heterogeneous stratum and the determination of critical parameters of the stochastic medium theory.problem in the construction industry, and helps reducing the material waste and budget cost. [ABSTRACT FROM AUTHOR]

Filter paper technique, humidity control technique and axis translation technique were used to study suction equilibrium time of unsaturated reticulate red clay. Test results show that: (a) suction equilibrium exists in both suction measurement or suction control using any technique in the tests; (b) suction equilibrium time of unsaturated reticulate red clay can be as short as several tens hour or several days for different suction measuring techniques, or long as several days or several tens day for different suction controlling techniques; (c) suction equilibrium time consumed in process of suction measurement is shorter than that of suction control using the same technique; (d) suction equilibrium time in measuring matric suction of unsaturated reticulate red clay using axis translation technique is shorter than that using filter paper technique; and (e) suction equilibrium time of drying process is much longer than that of wetting process, when suction is controlled using humidity control technique. [ABSTRACT FROM AUTHOR]