bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal-hydro coupling model of methane hydrate reformation in porous media
Authors: Li Lili , Zhang Pengwei , Yang Ming , Liu Baoguo
Published: May 2024

Methane hydrates are crystalline compounds found in marine sediments and permafrost regions. Methane hydrates remain stable under both low-temperature and high-pressure conditions. When a methane hydrate reservoir is heated or depressurized, methane hydrates become unstable and decompose into water and methane gases. The heat absorption process during the decomposition of methane hydrates influences the temperature field. Methane hydrate reformation occurs during the extraction process, significantly reducing the hydraulic conductivity of the reservoir and hindering the long-term stable extraction of methane hydrates. In this paper, a numerical model is established by coupling seepage and heat processes. The temperature variation owing to the heat absorption process of methane hydrate decomposition is quantified based on the proposed model. The effect of spatial lithology on methane hydrate conversion is also analyzed, and the results for hydrate, water, gas, and permeability in the model are summarized. The numerical model also reflects the heterogeneity of marine sediments. Finally, the sensitivities of different physical parameters (permeability and porosity) and pressure gradients to the reformation rate of methane hydrate reforming are discussed. The results of this study provide scientific data supporting the influence of secondary hydrate formation on long-term extraction efficiency in the actual engineering hydrate extraction process.
Simulation of controlled modulus column installation using a large deformation finite element analysis
Authors: Amarathunga T , Liyanapathirana D S , Fuentes W , Leo C J , Hu P
Published: May 2024

Controlled modulus columns (CMC) are widely used in ground improvement techniques where grout columns are constructed by penetrating an auger into the ground using the displacement approach. Numerical simulation of this problem is challenging owing to the large soil deformations associated with installation. Small strain-based finite element analysis procedures available in commercial finite element modeling software are unsuitable for simulating this problem because they cannot simulate large soil deformations around the auger during column installation. Hence, this study presents a numerical approach based on the finite element method to simulate the installation of CMCs. The numerical modeling technique adopted in this study considers large soil deformations around columns during penetration, and the proposed approach is based on remeshing and interpolation techniques. This method was developed using the Python development environment (PDE) within the ABAQUS/standard finite element program. It can penetrate columns below the ground surface without causing large mesh distortions. In this study, silty sand-type soil was considered; hence, the constitutive behavior was simulated using the Mohr–Coulomb criteria. The load-carrying capacity of a controlled modulus column was predicted and compared with an empirical equation based on the cone penetration resistance. The influence zone and failure mechanism of the soil during installation were determined by considering the stress distribution and soil flow pattern around the column.
Load-bearing response of deep content mixing soft soil composite foundation based on the geotechnical centrifugal model test
Authors: Lin Y , Tang G , Ma X , Ma C Y , Wang Z
Published: May 2024

Deep cement mixing (DCM) is an effective method of treating soft underwater soil foundations. Currently, the real-time failure development of a composite foundation cannot be obtained by most model tests of DCM pile foundation reinforcement. In this study, a circuit device for identifying pile failure and that can reflect the real-time working state of piles arranged at different positions in a soft soil composite foundation was developed. By applying this device to a geotechnical centrifugal model test, the load-bearing response process of a bank slope reinforced with a soft-soil composite foundation and DCM piles was studied. The failure development law of the DCM piles, ultimate surcharge of the bank slope, failure mode of the foundation, and the pile-soil stress ratio were determined from the test results. The law obtained in this study provides a reference for the application of DCM piles in underwater soft soil foundation engineering.
Semi-analytical solution for one-dimensional coupling consolidation of original soil and electro-osmotic layer using horizontal electrodes
Authors: Li Jian-Ping , Luo Wen-Dong , Chen Zhang-Long
Published: May 2024

The application of horizontal electro-kinetic geosynthetics for electro-osmotic consolidation is becoming increasingly widespread. Such horizontal electrodes are typically arranged at intervals, allowing pore water in original soil to pass through the intervals and penetrate into the electro-osmotic layer. In this study, a one-dimensional semi-analytical solution for a double-layered electro-osmotic system incorporating the original soil was presented and verified. The effects of the soil properties on the consolidation process were investigated. Results revealed that original soil can achieve a significant consolidation effect, even better than electro-osmotic dredged soil. A smaller permeability coefficient of original soil significantly prolongs the consolidation time, while a thicker original soil can improve the average consolidation effect of the two layers. The proposed model provides new electrode arrangement ideas and theoretical support for horizontal electro-kinetic geosynthetics for electro-osmotic reinforcement.
Research on construction parameters of stone columns for liquefaction mitigation in coral reef sand areas
Authors: Liwen Hu , Xiaocong Liang , Mingxing Zhu , Meng Chen , Xiong Xu
Published: May 2024

For loose coral reef sand with high fines content located in strong earthquake zones, it is necessary to choose stone columns as a liquefaction mitigation ground improvement method that can consider both drainage and densification functions. Taking the Tibar Bay Port project in East Timor as an example, the bottom-feed technology of vibrating stone columns was developed, and typical coral reef sand sites with different fines contents were selected as trial test areas. Experimental research was performed to study the construction parameters for onshore and offshore stone column processes. Tests showed that the vibratory process control parameters, quality acceptance standards, and control procedures proposed through research meet the anti-liquefaction requirements for both drainage and densification effectiveness. The different construction characteristics of onshore and offshore stone columns were also analyzed. Considering the particularity of underwater stone column construction, the research results can be used for stone columns reinforced grounds similar to coral sand onshore and offshore.
Research on bearing capacity of piles with negative skin friction based on field test
Authors: Song-tao WEI , Bo LI , Jian-fei YU , Jun LIU
Published: May 2024

There are extensive deep soft soil layers in the coastal areas of China, and the drainage consolidation method is widely adopted for foundation pretreatment in these areas. However, there are still dozens of centimeters of post construction settlement, which may produce negative skin friction on the pile foundation. To accurately estimate the magnitude of negative skin friction, two prestressed high strength concrete pipe piles with different pile end holding layers were used to conduct field tests. The development law of negative skin friction of pile foundation with soil consolidation is studied by simulating different pre-load height conditions of soil around pile. The monitoring results of field tests indicate that with the soil settlement around the pile, the dragload increases gradually and the neutral point moves downward. When the relative displacement between the pile and soil is 87 cm, the neutral point position of the end bearing pile is approximately 44.6-m deep, and the dragload is about 3640 kN, while the friction pile is 30 m and 2160 kN. The analysis shows that if the pile foundation construction is carried out during the foundation pretreatment, the dragload is considerably large, and this may lead to excessive settlement and damage of the pile.
A modified Prandtl upper-bound solution of basal stability for narrow-deep excavations in undrained clay
Authors: Qiao Yaqing , Huang Maosong , Shi Zhenhao , Zhang Zhongjie , Wang Haoran
Published: May 2024

In recent years, the construction of narrow-deep excavations has been steadily developing. Narrow-deep excavations exhibit a clear size effect in the basal heave stability analysis. However, the classical Prandtl mechanism ignores the size effect and influence of the inserted depth of wall penetration. Based on this, a modified Prandtl failure mechanism that considers the above factors was proposed in this study. Subsequently, a practical equation was derived to simplify the analysis process and obtain the safety factor against basal heave. The upper-bound solution provides a convenient and concise method for basal heave stability analysis of narrow excavations in undrained clay, and its feasibility was verified by comparing it with the results obtained by finite element limit analysis. The results showed that the proposed failure mechanism can provide a better upper-bound solution for the safety factor of the basal stability of narrow excavations than the classical Prandtl failure mechanism.
Responses of metro shield tunnels to an adjacent deep excavation in Shanghai soft ground
Authors: Fang Yingang , Jia Jian , Xie Xiaolin
Published: May 2024

Deformation in metro shield tunnels is a consequence of conducting adjacent deep excavations. Accordingly, this research examines the response of existing metro shield tunnels in Shanghai’s soft ground to nearby deep excavations, focusing on how tunnel deformation correlates with the distance to the excavation. Utilizing actual measurement data from metro shield tunnels located 12-45 m from an 11.5-24.1-m-deep excavation, the study initiates with a project overview before analyzing the deformation data of the metro tunnels. This analysis includes the settlement and transverse convergence of both upward and downward lines. Furthermore, by integrating the settlement history curve and settlement increment ratio statistics, the study explores the deformation of the metro tunnels across different construction stages of the adjacent excavation. Additionally, the effect of the distance to the excavation on metro tunnel deformation is discussed, considering identical excavation depths, supporting stiffness, construction levels, and soil conditions. This investigation aims to provide insights applicable to similar cases and inform future research.
Inrushing failure characteristics of deep shaft structures in soft soils based on material point method simulation
Authors: Wang Yu-Mo , Qiao Yong-Kang , Peng Fang-Le
Published: May 2024

In areas with soft soil, inrushing may occur during the construction of deep shaft structures under high water pressures, causing destructive accidents. Most studies on inrushing have used the finite element method. However, it is difficult to achieve a large deformation simulation because of mesh limitations. The material point method is not constrained by the mesh, and the material properties and motion information of the material are stored at the material points. Therefore, it can be used to effectively simulate large soil deformations. In this study, a numerical model for a deep shaft structure in Shanghai was formulated using the material point method to simulate the evolution of inrushing failure. The likelihood of inrushing damage at different excavation depths was analyzed. Soil heave at the bottom of the pit in the absence of inrushing was examined. The structural and environmental factors affecting the inrushing process are discussed. Strategies have been proposed from different perspectives, such as structure, environment, and construction methods, to reduce the damage caused by inrushing, thereby providing a reference for the safer construction of deep shaft structures.
Field test on application of tip grouting in enlarged head cast-in-place bored pile
Authors: Zhang Jiaqi , Zhao Chunfeng , Zhao Cheng , Wu Yue
Published: May 2024

Pile tip grouting is an important technique for improving the bearing capacity of cast-in-place bored piles. This paper presents a field experimental study on the effects of tip post-grouting in an enlarged head cast-in-place bored pile. The bearing data of the pile before and after the grouting were obtained through two load tests. The settling rod method was used to monitor the settlement at three critical sections, including the pile bottom during loading, while the method of rebar stress gauge was employed to monitor the strain of the pile shaft. The study results indicate that post-grouting at the pile tip significantly enhanced the bearing capacity of the pile and helped control the settlement at the pile top. A comparison between the measured and calculated settlement values at critical sections demonstrates the applicability of the settlement rod method and strain gauge method. Post-grouting at the pile toe effectively improved the side friction of the pile, resulting in smaller axial forces in the lower part of the grouted pile under equivalent loads.
Boundary effect of foamed cement paste under the influence of air-coupled impact-echo
Authors: Wan X , Zhang Z , Ye G , Zhang Y , Liu H
Published: May 2024

The air-coupled impact-echo method has been increasingly utilized for the detection of cement-based materials. In this study, an air-coupled impact-echo system is developed. This system evaluates the response of cast-in-place foamed cement paste blocks subjected to air-coupled impact-echo. The shape factor is calculated based on the acquired impact-echo spectrograms to analyze the boundary effects of the blocks. The results show that the values of the shape factor vary with the impact location, as the impact location from the edges of the blocks affects the air-coupled impact-echo response. Accordingly, a dimensionless factor is proposed to evaluate the boundary effect of block-like foamed cement paste. This study contributes to the application of the air-coupled impact-echo method for the detection of foam cement paste.
Analysis of the shear wave velocity structure of a soft-hard interlayered rock slope based on surface wave and microtremor survey
Authors: Peng M , Liang Y Y , Liu L , Shen J , He L K , Xue J F , Qin X Z
Published: May 2024

The information regarding the layered structure is pivotal to the stability analysis of soft-hard interlayered rock slopes. The variation in the shear wave velocity offers insights into the characteristics of the strata structure within a rock slope. In this study, a joint analysis method that combines the multichannel analysis of surface waves (MASW) and the microtremor surface method (MSM) was used to identify the layered structure of a soft-hard interlayered rock slope located in the Shandong Province, China. The survey lines were positioned on slope crests. For the MASW, the receivers were placed in line with an active seismic source. The MSM method uses a concentric circular array comprising seven receivers. Fundamental-mode dispersion data were extracted from the active and passive microtremor sources. The 1D velocity models were then inverted from the combined dispersion curves using a surrogate optimization algorithm. A 2D velocity profile of the investigated slope was constructed through linear interpolation, and it exhibited distinct characteristics of high- and low-velocity interlayers, consistent with the borehole data. Our results demonstrate that the joint analysis method provides a complementary approach to image velocity profiling of slopes, thus contributing to enhanced investigation depth and resolution in shallow layers owing to the wider frequency range of the dispersion curves.
Spatiotemporal Prediction of Rainfall-induced Landslides Using Machine Learning Techniques
Authors: Xiong Jun , Pei Te , Qiu Tong
Published: May 2024

Landslides cause significant damage to infrastructure and loss of life. Landslide susceptibility map (LSM), as an important reference for landslide hazard assessment, indicates prone areas of landslides. However, conventional LSM only predicts the spatial distribution of potential landslides, which cannot fully explain the occurrence of landslides at different times. In the present study, a spatiotemporal LSM is conducted to predict landslides both in space and time. A landslide database containing 223 recorded landslide events in southwestern Pennsylvania is used. Fourteen topographic spatial factors and eight rainfall temporal factors are used for machine learning (ML). Four ML models are applied in the study, including Logistic regression (LR), Support vector machine (SVM), Random forest (RF), and Gradient boosting machine (GBM). The results show that through cross-validation, RF outperforms the other algorithms with a value 0.86 of the area under the receiver operating characteristic curve (AUC score). The optimal model is used to generate spatiotemporal LSMs. It is concluded that by introducing spatial and temporal information simultaneously, ML models have the capability of learning the pattern of landslide occurrence both in space and time, providing an effective assessment tool to reduce catastrophic loss of landslide hazards.
Shield tunnel leakage detection using distributed optical fiber
Authors: Liu Pengfei , Ma Minglei , Wang Jianxiu , Long Yanxia , Cao Ansheng , Li Huboqiang
Published: May 2024

Leakage in operating tunnels is a serious problem during operating stage. In order to realize non-destructive detection of leakage in an operating shield tunnel, an optical fiber temperature measurement method based on Raman scattering and infrared thermal imaging technology is developed. The working principle of leakage monitoring with Distributed Fiber Optic Temperature Sensor (DTS) combined with time domain reflectometry (OTDR) technology are introduced. The distributed measurement of temperature field is realized in a typical tunnel. Infrared thermal imager is used to perform thermal imaging on the leakage area, and the temperature difference between the leakage area and the non-leakage area is 3.6 °C, which can meet the requirements of distributed optical fiber side leakage temperature accuracy. This illustrates the feasibility of quantitative monitoring of leaks in distributed optical fiber temperature sensing systems. The reasonable arrangement of leakage monitoring fiber in distributed fiber temperature sensing system is discussed in practical engineering.
Assessment of load test program for reliability-based design of piles
Authors: Ma Xiangyu , Hu Jinzheng , Li Xueshan , Zhang Jie
Published: May 2024

Quantifying the uncertainty of the bearing capacity of piles is crucial in the context of reliability-based design (RBD) for pile foundations. The utilization of site-specific load test data plays a pivotal role in reducing the uncertainty associated with bearing capacity, thereby enhancing the overall design of pile foundations. However, prior to initiating a load test program, there exists uncertainty both in the outcomes of the program and the potential benefits it may yield. This research endeavors to develop a method that allows for assessing the effectiveness of a load test program before its execution. The structure of this paper is as follows: firstly, it introduces a framework for evaluating the utility of the pile load test (PLT) program. Subsequently, it constructs a pre-posterior analysis to examine the anticipated benefits derived from the load test program. Finally, the proposed methodology is elaborated upon through a detailed example. This paper is valuable for enhancing decision-making in optimizing pile load test programs.
Three-dimensional stochastic model for stratigraphic uncertainty quantification using Bayesian machine learning
Authors: Wang Hui , Wei Xingxing
Published: May 2024

Data-driven geotechnics is an emerging research field that contributes to the digitalization of geotechnical engineering. Among the numerous applications of digital techniques in geotechnical engineering, interpreting and simulating stratigraphic conditions with quantified uncertainty is an essential task and an open question in geotechnical practice. However, developing an uncertainty-aware integration of subjective engineering judgments (i.e., geological knowledge) and sparse objective site exploration results (i.e., borehole observations) is challenging. This investigation develops an effective three-dimensional stochastic geological modeling framework based on Markov random field (MRF) theory and Bayesian machine learning to characterize stratigraphic uncertainty. The proposed model considers both stratigraphic uncertainty (inherent) and model uncertainty (imperfect knowledge). A stratigraphic modeling example was studied to demonstrate the effectiveness of the proposed approach. We envision that this approach could be further generalized to industrial practices to improve risk control in geotechnical engineering.
Multi-sample joint localization method for intrusion sources around underground pipelines based on cross-correlation convolutional neural networks
Authors: Chai Fu , Zhou Biao , Xie Xiongyao , Zhang Zixin , Han Jianyong
Published: May 2024

Improving the safety monitoring of underground pipelines is crucial for maintaining the structural integrity of critical infrastructure systems. This study introduces an innovative multi-sample joint localization method (MSJLM) based on cross-correlation convolutional neural networks (CC-CNNs) to identify intrusion sources in the vicinity of underground pipelines. Traditional approaches to detecting and locating pipeline intrusions often rely on a solitary sensor monitoring point, making them susceptible to errors and limitations. Presently, widely used distributed optical fiber testing methods tend to yield imprecise localization. In contrast, the MSJLM proposed in this study harnesses data from multiple samples effectively and combines them via correlation analyses to enhance precision and reliability. The CC-CNN framework used to process the collected data is demonstrated to be highly effective in extracting spatial features and recognizing patterns.
Monitoring the hardening process of cemented soil with polymer optical fibre
Authors: Zhibin Z H L , Zhonghao W , Xianfeng MA
Published: May 2024

Cement-soil can effectively improve the mechanical characteristics of soft soil and reduce the deformation of foundations through the physical and chemical processes of cement hydration. After mixing cement with soft soil, the hydration reaction of cement consumes a certain amount of water, which leads to a decrease in the water content. The early strength of cement-soil refers to the undrained shear strength within a few hours of mixing. The initial setting time of cement-soil can reflect its early strength development. In this study, polymer optical fibre (POF) sensors are used to visually monitor the early strength of cement-soil with different cement contents; the monitoring results show that the POF sensor can effectively visualize the hydration process of cemented soil. The cement-soil hydration process is divided into three stages: the initial setting time of the cement-soil is 13-15 h, and the final is 33-41 h. Furthermore, the cement content significantly influences the initial and final setting times of cement-reinforced soil. As the cement content increases, the initial and final setting times of the cement–soil decrease. This study proposes a new method for monitoring the strength of cement-reinforced soils.
Real-time railroad track components inspection framework based on YOLO-NAS and edge computing
Authors: Tang Youzhi , Wang Yi , Qian Yu
Published: May 2024

The demand for efficient track inspection systems in the rapidly evolving rail transportation field is more pronounced than ever. Hence, this study combines deep learning and edge computing for railroad track component inspection, focusing on the YOLO-NAS architecture. Our objective was twofold: to harness the advantages of YOLO-NAS for accurate and high-speed detection while addressing the computational constraints of edge devices. Consequently, YOLO-NAS-S-PTQ model achieved a remarkable balance, with 74.77% mAP and 92.20 FPS, on the NVIDIA Jetson Orin platform. By deploying this model on an edge device and utilizing a multiprocessor pipeline, we observed an inference speed of 60.468 FPS, which was nearly double the rate of its single-threaded counterpart. Field tests further confirmed the efficiency of the model, demonstrating a recall rate of 80.77% and an accuracy of 96.64%. These findings underscore the potential of YOLO-NAS in transforming traditional rail component inspection methods, significantly reducing human interventions and potential errors.
Hyperspectral imaging features for structural stress state assessment: An experimental study
Authors: Wang C , Huang H , Zhou M
Published: May 2024

To explore the feasibility of hyperspectral machine vision for detecting stress states of underground structures, this study utilized a hyperspectral camera to acquire spectral datasets from the surfaces of concrete and sandstone specimens under different stress conditions. Machine learning models were established to predict stress states based on raw spectral data and data pre-processed using the Savitzky-Golay (S-G) method. The results indicated that satisfactory outcomes were obtained with no pre-processing and S-G pre-processing. In addition, the hyperspectral response characteristics of concrete and sandstone under different stress states were investigated. The hyperspectral dataset of sandstone was observed to yield higher predictive accuracy than that of concrete. Finally, a comprehensive analysis of the performances of the principal component regression, partial least squares regression, and least-squares support vector machine models was performed over various datasets in terms of computed model evaluation metrics.
Crack monitoring for municipal sewer pipes using DFOST
Authors: Yuan Xun , Liu Yuepeng , Lin Peiyuan
Published: May 2024

The distributed fiber optic sensing technique (DFOST) provides an effective solution for long-term deformation monitoring of sewer pipelines under operation conditions due to occurrence of cracks. However, optical fibers attached on the pipeline wall might fail to capture all cracks as they are usually highly spatially scattered, resulting in misjudgment of pipe structural conditions. To address this challenge, this paper presents a novel deployment approach of distributed fiber optic monitoring system for pipeline cracks. First, the working principle of optical frequency domain reflectometry (OFDR) is explained. Second, the production of concrete pipe specimens with different optical fiber sensors deployment schemes is shown in detail. Finally, a comprehensive analyse of the results of visual inspection and fibre optic monitoring is completed. To evaluate the performance of this approach, experimental data from various cases were considered. The conclusion of this paper provides theoretical and empirical support for the application of distributed fiber optic sensors for pipeline cracks monitoring.
Tunnel indirect damage identification algorithm based on service train dynamic response time series
Authors: Li Qi , Zeng Kun , Xie Xiongyao
Published: May 2024

In this study, a tunnel indirect damage identification algorithm based on a service train dynamic response time series was proposed. First, the principles and processes of the proposed algorithm are introduced. The instantaneous frequency and spectral entropy of the trend and seasonal terms of the train dynamic response decomposed by Seasonal and Trend decomposition using Loess are calculated, respectively, to further extract the time-frequency features of the signal. The calculated sequence is input into the Bi-directional Long Short-Term Memory network, and the type of damage case is the output. Second, the feasibility of the algorithm is verified using a model test. Finally, the key links in the algorithm are discussed. The results indicate that the proposed algorithm can identify damage cases with a small number of training and test sets, and the accuracy of the test set can reach 83.33%. Through time-frequency feature extraction and normalization processing, the length of the network input sequence is reduced, the training speed is increased, and damage identification can be realized without a deep network.
Bayesian Back Analysis of Axially Loaded Pile Response Using Fibre Optic Strain Data
Authors: Wang M , Leung Y
Published: May 2024

The load-transfer method has been extensively used to evaluate the deformation behavior of foundation piles, with the nonlinear load-settlement behavior of a pile-soil system modeled using load-transfer curves. Although load-transfer models have a considerable impact on the pile response, the model parameters are usually estimated empirically from soil parameters using transformation models, and the associated uncertainties are often neglected. Fiber optic sensing technology provides detailed axial strain information along the entire length of a pile; however, the full potential of such utilization has not yet been realized. This paper presents a Bayesian back analysis method for statistical descriptions of load-transfer curves and pile responses based on fiber optic measurement. A pile test case study is used to illustrate the proposed method, and several candidate model configurations are compared. The results show that the predicted pile response generally matches the measured data, and the quantified uncertainty allows for a better understanding of the possible ranges of the pile response, in addition to the single best-estimate result.
Predicting base resistance of super-long piles using a random forest model: A case study from Ho Chi Minh city
Authors: Weng Kailiang , Jia Mincai
Published: May 2024

The prediction of the base resistance for long piles is usually challenging because of the impact of material characteristics and the influence of the nature of the surrounding soil. Artificial intelligence models have been applied in various geotechnical engineering fields, and significant results have been achieved. Based on a well-instrumented static load test dataset (1131 data points) from various projects in the soft soil area of Ho Chi Minh City, this study established a random forest (RF) model considering five input parameters, including the applied load, load point displacement, axial stiffness, standard penetration test value of the soil beneath the pile toe, and the distance from the load point to the pile toe. Twenty percent of the data was designated as the test set, which was used to make predictions using the established model. The results show that the RF model has good predictive performance in terms of prediction accuracy and reliability. A sensitivity analysis of the input factors provided a deeper understanding of the base resistance mechanism, which is important in pile foundation design practice.
Development and key technologies for architectural design and technical solutions of CIM platform: A review
Authors: Fang J , Xie X , Xu J
Published: May 2024

The integration of building information modeling (BIM), geographic information systems (GIS), 5G, IOT, cloud computing, big data, artificial intelligence, and other technologies in urban management has become a new and rapidly developing trend in recent years. However, most of the existing research on the construction of city information modeling (CIM) platforms based on the integration of BIM and GIS technologies focuses on integration technologies, and there is a lack of theories, methods, and standards for further data analysis and mathematical modeling. This paper analyzes and summarizes the actual situation of the application of recent research papers in the BIM field and the application of CIM platform pilot projects, reviews the application of BIM and GIS technologies in smart cities, and discusses future trends. For example, the construction of a basic platform for smart cities requires the establishment of a three-dimensional visual CIM platform with functions such as the planning review, architectural design plan review, construction drawing review, completion acceptance filing. A smart city is built by analyzing the cyber security risks faced during the construction. The technical, management, and operational measures of the security system provide guidance and reference for the secure construction of smart cities. This involves promoting the reform of the construction work system driven by data resources obtained from government information, and the establishment a new digital government construction management system through the “separation of management and transportation.” These analyses highlight the evolution of the CIM platform construction. The results indicate that the use of key technology integration in the construction of a CIM platform requires a system theory that goes beyond integration technology and mathematical modeling methods for a detailed application. It involves analyzing the deep integration of key technologies and business processes in the CIM platform.
Intelligent prediction and evaluation method of optimal frequency based on PSO-BPNN-AdaBoost model
Authors: Chen X B , Hao Z R , Xie K , Li T F , Li J S
Published: May 2024

To achieve rapid and accurate determination of the optimal compaction frequency for high-speed railway subgrade materials, a method based on the PSO-BPNN-AdaBoost model for intelligent frequency estimation is proposed. Firstly, the Particle Swarm Optimization (PSO) algorithm is introduced to obtain the optimal hyperparameters of the Backpropagation Neural Network (BPNN), and then the PSO-BPNN-AdaBoost model is established by integrating the AdaBoost ensemble algorithm. Secondly, taking graded gravel fill material as an example, the Grey Relational Analysis algorithm (GRA) is employed to identify the main controlling features affecting f
op as input features for the model, and the predictive performance of the model is evaluated. Finally, the model’s reliability is verified through ablation analysis. The results indicate that the PSO-BPNN-AdaBoost model demonstrates higher predictive accuracy. The main controlling features influencing f
op are revealed to be the maximum particle size (d
max), gradation parameters (b, m), coarse aggregate elongation index (EI), Los Angeles Abrasion (LAA), water absorption rates (W
ac, W
af).
How to quantify the tunnel structural resilience in longitudinal direction: a discussion on the index and its effect
Authors: Hua Y S , Huang H W , Zhang D M , Liu X M
Published: May 2024

Shield tunnel is prone to longitudinal differential settlement due to the characteristics such as segmental linings and unpredictable changes in multiple uncertain environments. Excessive differential settlement may deteriorate the safety and operational serviceability of the shield tunnel. Resilience has been increasingly applied in structural performance assessment given that it can evaluate the ability of structure to absorb the disruption and to restore the performance level. However, the resilience index and analysis framework for tunnels are quite vague and still in the developing phase. In this paper, a resilience analysis framework is introduced, and the detailed model to quantify the resilience of shield tunnel is presented. The cumulative settlement, maximum, and average value of differential settlement are selected as the performance indexes, because they can reflect the ability of the tunnel to ensure the structural safety and meet the waterproof requirements of the circumferential joints. Then, the effects of these indexes are analyzed using a real case in Shanghai. The results show that the resilience grades calculated using the three performance indexes are different, and the cumulative settlement is regarded as the better index.
Mechanical properties of sulfate saline soil stabilized by coal gangue-slag composite geopolymers
Authors: Yang Xiaoyun , Lin Cheng
Published: May 2024

Geopolymers, which are composed of solid waste, are eco-friendly binders characterized by rapid hardening and high strength. Using geopolymers to stabilize saline soils presents a sustainable solution for soil improvement. This study investigated two geopolymers, HG and SG, composed of a coal gangue-slag composite, to improve saline soils. The stabilized soils were prepared by blending geopolymers with saline soils in varying proportions of 10, 20, 30, and 40% by weight. The strength of the stabilized soils was evaluated based on the geopolymer dosage. Moreover, we examined the strength of the stabilized soils with curing time and elucidated the underlying mechanisms using microscopic analyses including XRD, FTIR, and SEM. This study revealed that: 1) the SG geopolymer outperformed the HG geopolymer in soil strength enhancement; 2) cohesion of the stabilized soil increased as the dosage and curing time increased, while the internal friction angle showed no clear trend; 3) the geopolymer stabilized soil mainly contained quartz, C-A-S-H, N-A-S-H, and C-N-A-S-H gels, and these gels were distributed on the soil particle surface and within the interstitial voids, improving the soil strength, and 4) in saline soil engineering, HG or SG geopolymer dosages should be above 30% and 20%, respectively.
Seismic response analysis and resilience study of Qingdao 2nd submarine tunnel using the finite element method
Authors: Zhang Q Y , Zhang W , Xue Y D
Published: May 2024

Earthquakes, as considered a highly destructive and unpredictable natural disaster that poses significant challenges for engineers designing underground structures. Incorporating seismic considerations is important to ensure the safety and stability of such structures. Therefore, it is crucial to analyze the response of tunnels to earthquakes and establish an evaluation index for their resilience, which would help guide projects toward improved safety. In this paper, we use numerical simulations to study the seismic impact on the Qingdao 2nd Submarine Tunnel according to different lining thicknesses (25-75 cm) and varying stratum conditions. Through adjustments to lining thickness and stratum conditions, a total of 30 numerical simulation experiments are conducted. These experiments contribute to the creation of the resilience evaluation index. The results of the study indicate the following trends: 1. Increasing lining thickness reduces the stress and deformation along the lining, though the effect stabilizes around 45-cm thickness. 2. Poor surrounding rock conditions lead to increased stress and deformation along the lining, especially near fault fracture zones. 3. The culmination of the study involves the creation of a resilience evaluation index, which serves as a practical guidance for tunnel construction in real-world projects.
Feasibility study of geosynthetic vegetation substrate for hard-surface ecological restoration part 2: Biodiversity and environmental effects
Authors: Chen L Y , Qin C R , Qiu T , Wu J Y , Guo J , Yan X
Published: May 2024

Current ecological restoration techniques often face challenges on steep and hard surfaces (e.g., concrete or rock surfaces) because of their reliance on soil as a vegetation substrate. Two geosynthetic-based ecological restoration techniques were proposed in which a geosynthetic material was used to replace the soil as a vegetation substrate on hard-surface slopes. In the first technique, vegetation is planted directly on the geosynthetic vegetation substrate (GVS), where the GVS provides water to the vegetation and room for vegetation roots. In the second technique, Hygrophila ringens is planted on the GVS. Hygrophila ringens exhibits rapid growth initially and then dies, creating a layer of humus over the GVS. A one-year vegetation growing test demonstrated that the designated vegetation thrived on the GVS and various foreign vegetation also began to grow on the GVS. The variety of vegetation indicates that the GVS not only successfully sustained the designated vegetation but also helped in the ecological restoration and improved the biodiversity on the hard-surface slopes.
Mitigation of soil frost heave with fungi
Authors: Zhang X J , Jiang Y S , Fan X D , Yu X
Published: May 2024

Frost heave and thaw weakening can impose engineering issues on cold region infrastructures, including pavements, slopes, pipes, foundations, and buildings. This study investigated the potential of fungi treatment to mitigate the frost susceptibility of soils. Fungi were grown with organic waste to develop fungal mycelium. Subsequently, it is introduced into the soil. A sensitivity study was conducted on the influence of fungi centration on soil behaviors. The volume change behaviors when subjected to freezing or thawing were monitored. The results indicated that both soil frost heave and thaw weakening were reduced significantly with fungi treatment. The mechanisms are investigated with the measurement of the soil water characteristic curves. The introduction of fungi treatment affected the SWCC and soil water affinity. These affect the moisture transport when soil is subjected to freezing/thawing. Subsequently, the volume changes were suppressed.
Application of PISA method for monopile design in layered soil
Authors: Wang Huan , He Ben , Nallathamby Sivasithamparam , Yang Shaoli , Huynh Khoa
Published: May 2024

The foundation design for offshore wind turbines (OWTs) is critical to ensuring their structural integrity and long-term stability. Large-diameter monopiles are widely used for OWTs owing to their proven effectiveness. The conventional design approach, derived from the oil and gas industry’s p-y model, has limitations when applied to monopiles for OWTs. Consequently, a novel design method based on the PISA joint industry research project was developed, which extends beyond the traditional lateral soil resistance (p-y curves) and incorporates additional soil reaction components from shaft friction, pile base shear, and base moment. Unlike the simplistic rule-based conventional approaches, the proposed method necessitates site-specific 3D finite element (FE) simulations for precise calibration of soil reaction curves. Although successfully applied in European offshore wind farms, the PISA method’s performance in regions with distinct seabed compositions, such as China, remains to be verified. Therefore, this paper presents a comprehensive case study conducted at the Xiangshan wind farm, a representative site characterized by layered soil. The study employed in-situ investigations (cone penetration test, borehole) and laboratory tests (direct simple shear, bender element) to delineate the seabed soil profile and derive essential soil parameters for accurate foundation design. To facilitate the design, an Abaqus-based design tool was developed, which automated the extraction of soil reaction curves from the 3D FE simulations, calibration of PISA springs, and execution of one-dimensional beam-spring analyses employing Timoshenko beam theory. Comparative analyses were performed on the computed responses of piles, encompassing load-deflection curves, pile deflections, and bending moment profiles. The outcomes from the 3D FE simulations, uncalibrated rule-based PISA model, and calibrated PISA model were compared to validate the PISA method for monopile design in layered soil conditions.
Anchor chain profiles in sand based on centrifuge model tests
Authors: Rui S J , Zhou Z F , Liu Z Q , Jostad H P , Wang L Z , Guo Z
Published: May 2024

The rapid development of floating wind turbines (FWTs) has brought new challenges to their mooring systems in shallow water of 50-200 m. The sand seabed, which is widely distributed in offshore regions, is often encountered in the service of FWTs and influences the anchor and mooring line design. The anchor chain is primarily adopted as the part interacting with the seabed, and its configuration in the seabed is vital for anchor design. However, a complete understanding of the chain configuration in sand is yet to be achieved. To address this, a group of centrifuge model tests using a model chain were conducted to simulate the chain embedment behavior in carbonate sand. During the tests, the chain position and soil deformation were captured using the Particle Image Velocimetry (PIV) method. A calculation model was adopted to predict the chain configuration in the sand, compare it with the centrifuge test results, and then analyze the differences between them. Finally, suggestions for model improvement were discussed.
Numerical simulation of offshore monopiles with reinforcement in shallow soil layer
Authors: Zhu Tao , He Rui , Guo Zhen
Published: May 2024

With the development of large-scale offshore wind turbines (OWTs), monopile foundations require larger diameter and greater embedded depth to satisfy the higher bearing requirements. Large-diameter monopiles for OWTs are mainly loaded horizontally, and the horizontal resistance provided by the shallow soil plays an important role in the loading of the monopile foundation. Therefore, shallow soil reinforcement (such as cement grouting and bio-grouting) is an effective method to improve the bearing capacity of the monopile. In this study, the lateral static loading mechanism of a shallow-layer reinforced monopile was investigated by finite element method (FEM). The effect of reinforcements with different stiffness values (elastic modulus), different strengths (cohesion and friction angle) and different reinforced ranges (width and depth) was analyzed on the lateral bearing capacity, deformations, soil resistances, and soil resistance per unit length to pile deflection (p-y) curves of monopiles. Based on the numerical results, an empirical formula was proposed for predicting the reinforcement coefficient of the bearing capacity. The effects of different reinforcement parameters on the distribution of soil resistance were analyzed, and the soil resistances obtained by FEM were compared with those from a theoretical formula. It was found that the resistance provided by the reinforced soil was clearly reduced at the interface with the unreinforced soil, and the resistance of the unreinforced soil was not significantly affected by the reinforced soil.
Stress stress-strain behavior of hydraulic filled coral sand subjected to internal erosion
Authors: Ding H Z , Wang X Z , Wen D S , Peng H , Liu K C
Published: May 2024

Coral sand foundations lose fine particles under the action of groundwater infiltration. As the soil skeleton structure deteriorates, the foundation becomes uneven and may even collapse. In this study, a triaxial drainage shear test of coral sand is used as a quantitative control method for the loss of fine particulate soil, and the effect of internal erosion on the mechanical behavior of coral sand is evaluated. An experiment is used to demonstrate that erosion leads to a decrease in the peak shear strength and residual strength of coral sand. Erosion has different effects on coral sand with different fine particle contents, and the effects on the friction angles of coral and terrestrial sand are also different. The secant modulus E50 and peak secant modulus Ep gradually decrease as the loss of fine particles increases. The effect of fine particle loss on the peak secant modulus Ep is significant at fine-particle losses exceeding 10% for a fine-particle content of 20%. The loss of fine particles creates new pore spaces in the coral sand, which, in turn, affects the stability of the original soil skeleton. Erosion has been shown to have an effect on the gradational features of coral sand, leading to the phenomenon that the dilatancy effect increases as a function of the amount of erosion that takes place. To prevent uneven foundation settlement caused by subsurface erosion in engineering designs, it is important to consider the gradation characteristics and fine particulate content of coral sand, which affect the stability of coral reef foundations.