underwater_const_syts

Underwater construction 2025

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03 - Control of nonlinear offshore platforms using semi-active tuned mass damper inerter under combined wave and wind loads

Authors: Seyyed Ali Mousavi Gavgani, Seyed Hossein Hosseini Lavassani, Gebrail Bekdas This paper studies the Semi-Active Tuned Mass Damper Inerter (SATMDI) for reducing vibrations in offshore platforms responding to wind and wave loading. It uses an interval type-2 fuzzy logic controller (IT2FLC) optimized with an observer-teacher-learner-based optimization algorithm. Results show that SATMDI + IT2FLC can greatly reduce energy effects, preventing structural plasticity, with example reductions of 91% in inter-story drift and 83% in absolute acceleration for a 100-year loading scenario.

04 - A Comprehensive Study on Environmental Impacts of Offshore Platforms Abandonment and Decommissioning in Malaysia.

Authors: Nuraiesya Khanoon Thariq Khan, Nurfarah Farhana Nurisman, Asheeka Razali, Mohd Haris Abdul Rani PETRONAS plans to increase the abandonment and decommissioning of offshore platforms from 2024 to 2026. Malaysia's oil and gas sector, contributing about 20% to the GDP, requires eco-friendly methods to prevent environmental harm. The study reviews sustainable dismantling practices, balancing economic and ecological needs.

05 - Tether analysis and stability investigation of space rocket launch offshore compliant platform in regular seas.

Authors: Srinivasan Chandrasekaran, Ashish Unnikrishnan, and Adwait Panindre This study looks at the stability of a multi-utility offshore platform for rocket launches, focusing on tether dynamics and platform behavior. The platform, modeled in ANSYS AQWA, has buoyant legs and a topside linked by ball- and-socket joints, allowing motion while keeping rotations separate. The extended topside needs stability checks due to pitch moments. Free-decay tests show rigid heave and pitch motions (~3 s) and flexible surge motions (~150 s). Dynamic tether analysis in different sea states shows simultaneous tether failures significantly affect platform stability, causing major shifts in heave and pitch.

06 - Design of a Semi-Submersible floating platform for Floating Offshore Wind Turbine (FOWT) IEA 15-Megawatt

Authors: Zulqarnain Ali, Ahmad Hassan, Sascha Kosleck, Ghaith Esber This study proposes solutions for designing a semi- submersible platform for a 15-MW wind turbine, located 300 meters deep with a height of 165 meters above water. It uses structural steel and concrete for stability and examines the platform's dynamics while ignoring mooring effects. Structural analysis includes pitch and stability calculations. Advanced simulations assess heave responses and wave interactions, achieving a 20% reduction in dynamic response and 25% improvement in energy efficiency. The framework aids in marine engineering, and future work may include testing and machine learning for better design.

13 - Analysing the legal and regulatory framework for decommissioning offshore platforms: a comparison between brazil (br) and the united kingdom (uk).

Authors: Elesito Lelo-Mali Cairo de Deus, José Adolfo de Almeida Neto, Attawan Guerino Locatel Suela This article analyzes the legal aspects of the decommissioning process in the United Kingdom and Brazil through a systematic literature review. It examines norms related to offshore platform decommissioning in both countries, finding that they align their policies with international sustainability standards. However, implementation issues arise, especially in Brazil, due to conflicts of interest. The study suggests areas for future research to improve policy application and resolve these conflicts.

14 - The impact of platform motion on the aerodynamic characteristics of floating offshore wind turbine arrays.

Authors: Xiang Li, Qing Xiao, and Yang Huang Floating offshore wind turbines (FOWTs) are gaining attention. This paper examines how platform motion affects the aerodynamic features of a FOWT array using a high-fidelity numerical tool developed from OpenFOAM, a powerful, open-source software for computational fluid dynamics (CFD). Three turbine arrangements are simulated, showing significant wake interactions. The capacity factor varies by layout, while platform motion influences power fluctuations. A coupled model considering both pitch and surge motion is needed.

01 - Effects of Cover-Plate Geometry on the Mechanical Behavior of Steel Frame Joints with Middle-Flange and Wide-Flange H- Beams

Author: Osama Zaid Yahya Al-Ansi, Linfeng Lu, Saleem Mohammed Ali Ahmed AL-Saeedi and Bingyou Liu This study explores the mechanical behavior of cover-plate reinforced connections in steel frames, addressing gaps in current design standards. Results show that cover plates improve load-bearing capacity and ductility by relocating plastic hinges outward from joint regions. The study also recommends cover-plate thickness should be at least 0.3 times the beam height, ensuring the combined thickness does not exceed the column height. These findings provide practical guidelines for designing resilient steel frame connections in seismic regions.

12 - Bolted Flange Connection Leakage: a Systematic Review of Monitoring Challenges and Technologies

Authors: Ben Cloostermans, Dick Pronk, Björn Bruckenburg, Sidney Goossens, Tigran Baghdasaryan, Francis Berghmans This article reviews various techniques to enhance the safety, reliability, and environmental compliance of bolted flange connections in industrial systems. It emphasizes the importance of proper installation processes to achieve optimal gasket surface pressure for leakage prevention and highlights the need for robust monitoring systems. The article explores both traditional and advanced monitoring strategies, weighing their effectiveness in leak detection and highlighting innovative approaches for enhancing long-term monitoring.

15 - Gas Pipeline Leakage Risk Analysis Based on Dynamic Bayesian Network

Author: Zhenping Wang, Xiaoyun Gui, Weifeng Wang, Xuanchong Zhao, and Xiaohan Ji A dynamic Bayesian network analysis is proposed to address high uncertainty and leakage risk in gas production pipelines in high-sulfur fields. The model uses Bow-tie model analysis to summarize risk sources and accidents, and a temporal dimension to construct a dynamic Bayesian network model. The study reveals that flow, valve, and pipeline status are key factors in gas leakage accidents, and six risk sources, including medium corrosion, are identified.

17 - Experimental Study on Pipeline–Soil Interaction in Translational Landslide

Authors: Tianjun Xue, Lingxin Liu, Jianlei Zhang, Mengjie Dai, Gengyuan Shi, and Xinze Li This study investigates the interaction between pipelines and soil in translational landslide zones using large-scale indoor model tests. Results show that failure in translational landslides is characterized by initial sliding at the slope crest, driving lower soil mass, and resulting in global slope instability. Pipelines traversing slopes laterally enhance slope stability by providing anti-sliding resistance. The study offers insights for improving pipeline safety and reliability.

18 - Study of the mechanical properties of double line pipelines under silty sandstone and pipeline coupling.

Authors: Cun-dong Xu, Wen-hao Han, Jin-xi Xia, Jun-kun Nie, Jun Cao, & Zhi-hang Wang This study examines the impact of filling thickness and internal water pressure on the stability of a water supply pipeline. It uses a numerical simulation method to study the influence of different filling thicknesses and internal water pressures on the pipeline's mechanical properties. Results show that soil filling and single-layer filling thickness increase vertical displacement and tensile and compressive stresses.

20 - Horizontal Directional Drilling: A Solution to Oil and Gas Pipeline Vandalism and Theft in Nigeria

Authors: Ogunweolu Oluseyi Emmanuel This study explores the use of horizontal directional drilling (HDD) as a potential solution to combat oil pipeline vandalism in Nigeria. The research aims to analyze the advantages, challenges, and economic feasibility of HDD in Nigeria's oil and gas sector. The study will examine case studies and literature to assess the economic feasibility of HDD and compare it with traditional methods. The findings will contribute to the existing knowledge on combating oil and gas pipeline vandalism in Nigeria and encourage policymakers and stakeholders to consider HDD as a viable solution.

21 - Influence of ground load on adjacent oil and natural gas pipelines

Authors: Zhengwei Guo, and Yinchun Gong Ground building causes significant stress on buried pipelines, potentially destroying them if the stress exceeds the pipeline's yield strength. Research uses theoretical and numerical methods to analyze stress and deformation of pipelines. The study investigates the impact of distance between pipeline and ground building on stress and deformation, providing valuable insights for pipeline construction.

22 - Mathematical And Experimental Investigation Of Vibration Isolation Characteristics Of Negative Stiffness System For Pipeline

Authors: Sharif Md Yousuf Bhuiyan, Adar Chowdhury, Md Shahadat Hossain This document analyzes the impact of vibration on pipelines and their equipment, focusing on the development of a negative stiffness system. The study aims to reduce frequency and vibration in pipeline systems by adding a negative stiffness system to the main structure. This will help maintain safe and secure operations, ensuring the safety and efficiency of pipelines.

23 - Mechanical Response of Pipeline Leakage to Existing Tunnel Structures: Insights from Numerical Modeling

Authors: Ruichuan Zhao, Linghui Li, Xiaofei Chen, and Sulei Zhang This study investigates the mechanical response of existing tunnel structures to pipeline leakage under different layout conditions using numerical modeling. Results show that horizontal pipeline-tunnel distance does not influence leakage zone development but significantly alters seepage path length and interface contact area. This information is crucial for optimizing urban underground design and construction guidelines.

27 - Analysis of the Causes of Excessive Noise and Vibrations of Live Steam Pipelines

Authors: Damian Pietrusiak, Jerzy Czmochowski, Artur Górski, Artur Iluk, Przemysław Moczko, and Michał Paduchowicz This article investigates noise and vibration issues in a live steam pipeline using a scanning laser vibrometer and acoustic camera. A discrete model and FEM analysis identify noise sources and propose methods for eliminating harmful noise.

28 - Dynamic response behaviors of buried pipelines subjected to the impact of spherical falling objects in cold regions

Authors: Qiaozhen Li, Chao Wang, Peng Wang, Min Luo, Hao Wang, Ye Lu The study examines the dynamic response behavior of buried pipelines in cold regions, considering the nonlinearity of pipeline material, falling objects, and frozen soil. Results show that factors like diameter-to-thickness ratio, impact velocity, and soil water content significantly influence pipeline deformation and residual stress. Controlling these factors can improve pipeline resistance to external impact damage.

29 - Optimising ML Pipeline Execution via Smart Task Placement

Authors: Pedro Rodrigues, Julio Corona, Mário Antunes, and Rui L. Aguiar This paper introduces a modular and flexible placement system for Machine Learning Operations (MLOps) pipelines, which automatically allocates tasks to suitable machines, reducing execution and waiting times. The system outperforms baseline methods and the Kubernetes default scheduler, demonstrating potential for improved resource utilization and faster ML model development in heterogeneous environments.

30 - Vibration Control of Deepwater Offshore Platform Using Viscous Dampers Under Wind, Wave, and Earthquake

Authors: Kaien Jiang, Huiyang Li, Guoer Lv, Lizhong Wang, Lilin Wang, and Huafeng Yu This study explores the use of viscous dampers (VDs) to reduce the vibration of a deepwater offshore platform under wind, wave, and earthquake action. A finite element model was used, and the results showed that VDs diagonally placed at each structural level effectively suppress platform vibrations. Under seismic excitation, the system reduced maximum deck acceleration, velocity, displacement, and base shear force by 9.95%, 22.33%, 14%, and 31.08%, respectively.

31 - Research on High-Performance Underwater-Curing Polymer Composites for Offshore Oil Riser Pipes

Authors: Xuan Zhao, Jun Wan, Xuefeng Qv, Yajun Yu, and Huiyan Zhao This study developed an underwater-curing composite material for offshore oil and gas extraction riser pipes, addressing corrosion issues and poor adhesion. The material, based on a polyisobutylene and butyl rubber blend system, exhibits high peel strength, low water absorption, and stability across a wide temperature range. The innovative solvent-free two-component epoxy system achieves rapid surface drying and pull-off strength exceeding 3.5 MPa. The material's fundamental properties and operational performance were determined, extending the service life of the pipes.

32 - Symmetric and Asymmetric Semi-Metallic Gasket Cores and Their Effect on the Tightness Level of the Bolted Flange Joint

Authors: Przemysław Jaszak, and Rafał Grzejda This paper explores the impact of semi-metallic gasket core shapes on bolted hinge joints. Its authors found that asymmetric gaskets provide higher strain on the sealing graphite layer and have a more uniform strain distribution. Additionally, asymmetric gaskets reduce leakage rates by around 60% compared to symmetric ones. The main leakage path is through the porous graphite layer.

37 - Advanced resource operation of main natural gas pipeline using CFD modeling methods

Authors: G.G. Ismayilov, F.B. Ismayilova, A. Nagizadeh The oil and gas industry's future operation of pipelines is crucial, and periodic checks are necessary to diagnose their technical condition. This paper investigates residual operating resources and wall thickness using an OLYMPUS 27 MG Ultrasonic Thickness Gauge. The study calculates minimum allowable thicknesses based on internal pressure and operational loads, determining the possibility of safe operation. Both analytical methods and modern software were used for calculations, including a three-dimensional spatial model and strength and stability calculations.

38 - A Novel Quadrilateral-Shaped Vibration Isolation Platform and Its Application in the Offshore Floating Platform

Authors: Zhenbin Guo, Jing Bian, Liangyu Li, and Ning Su This study presents a quadrilateral-shaped vibration isolation platform (QVIP) for offshore wind platforms, combining negative stiffness elements and optimized damping for high-static-low-dynamic stiffness. The design offers improved stability and effective vibration control, overcoming traditional trade-offs between isolation and load-bearing capacity.

39 - Prediction of Failure Pressure of Sulfur-Corrosion-Defective Pipelines Based on GABP Neural Networks

Authors: Li Zhu, Yi Xia, Bin Jia, and Jingyang Ma This study explores the degradation and failure prediction of pipeline materials in sulfur-containing environments, focusing on X52 pipeline steel. Despite surface corrosion and reduced structural load-bearing capacity, X52 steel's intrinsic mechanical properties remained within standard ranges. A Johnson-Cook constitutive model and a genetic algorithm-optimized backpropagation neural network were developed to predict failure pressure and corrosion rate in acidic environments.

02 - Design and development of a low-cost, eco-friendly forklift for sustainable logistics management

Authors: Asif Jalal, Muhammad Farooq, Izza Anwer, Nasir Hayat, Adeel Munir, Imran Zahid, Noreen Sher Akbar, M. Hamza, M. Nouman, and Fahid Riaz This article discusses the development and evaluation of an automated robotic forklift prototype designed to reduce injuries and improve efficiency in material handling within warehouses. Current statistics highlight the significant number of injuries and fatalities associated with manual forklift operations, prompting the need for safer alternatives. The prototype features advanced mobility capabilities, a remote operating system, and robust structural integrity, demonstrating its potential as a cost-effective and eco-friendly solution for industrial applications.

11 - Sustainability assessment of different pipeline materials in freshwater supply systems

Authors: Imran Mir Chohan, Azlan Ahmad, Naraindas Bheel, Taoufik Najeh, and Abdulrazak H. Almaliki This article explores the environmental effects of different pipeline materials used in freshwater supply systems through a life cycle assessment (LCA) framework. Utilizing SimaPro software, the research evaluates four pipeline materials and identifies that steel has a notably higher environmental impact during the manufacturing phase compared to others. It also assesses the installation phase, revealing that plastic pipelines produce significant impacts during installation. A case study in Seri Iskandar demonstrates that using environmentally sustainable materials can substantially reduce various environmental impacts associated with pipeline manufacturing and materials.

19 - Calculation of steel corrosion rate of reinforced concrete slab based on rust expansion crack

Authors: Duo Wu, Ziyi Zou, Hao Wu, Weihong Wan, Shangchuan Zhao, Jian Cao This study develops a refined calculation model that enhances the understanding of how distributed reinforcement affects crack propagation in reinforced concrete. It aims to improve nondestructive corrosion assessment methods through both experimental and theoretical analyses. The research incorporates the relationship between crack width and corrosion rates, validated through comparisons with existing models, ultimately contributing to more reliable quantitative detection of reinforcement corrosion in concrete structures.

26 - Modeling of the dynamic response of a wearable composite for an underwater shock wave

Authors: Jiangrui Qian, Xuhua Yu, Wenwu Liu, Guoyang Huang, Xia Liu, Yukun Wen, Yiqun Fang, Jun Li, and Jiajun Xu The article discusses the destructive effects of underwater explosions and highlights the urgent need for research not just in engineering protective materials, but also in human protection materials. A new composite material, combining carbon fiber laminate, artificial cartilage foam (ACF), and Kevlar fabric, has been developed to reduce injuries from explosive impacts. A finite element model was created to analyze the composite’s effectiveness while considering various factors like plate thickness and core panel density, along with an equivalent human body representation.

40 - Fiber-Reinforced Polymer Laminates in Aviation and Structural Engineering: A Synthetic Comparison of Performance Requirements, Design Principles, and Defect Assessment Procedures

Authors: Joana Janeikaite, Ieva Misiunaite, and Viktor Gribniak The article explores the divergent approaches to fiber- reinforced polymer (FRP) laminates in aviation and structural engineering, highlighting the unique challenges of each domain. While aviation prioritizes certification and fatigue resistance, structural engineering focuses on durability and environmental impact. The review synthesizes information from 168 literature references to propose integrated modeling and inspection frameworks that aim to harmonize the precision found in aviation with the practical considerations of structural engineering for improved performance and reliability of FRP composites.

41 - Hydrodynamic Characteristic Around the Riprap Protection of Monopile Wind Power Foundation with Scour Pit During Scour

Authors: Tongshun Yu, Li Wang, Congbao Mei, and Xiaofeng Dong This article examines the role of riprap protection in offshore wind power foundations, particularly its impact on hydrodynamics during scour events. Through experimental data on the soil failure process and a numerical model simulating the interaction between currents, the study reveals that intact riprap increases flow velocity and horseshoe vortex range around the monopile while decreasing pressure. As riprap becomes scoured, water cross-section increases, leading to reduced velocities and altered vortex patterns, ultimately affecting the stability of the foundation.

42 - The Mechanism Underlying the Influence of Temperature on the Fracture Toughness of Dissimilar Steel Welded Joints in Nuclear Power Plants

Authors: Jiahua Liu, Aiquan Zheng, Lei Wang, Hongwu Xu, Feifei Ji, Liqun Guan, and Jiong Luo This study investigates the fracture toughness (JQ) of the isolation layer in dissimilar metal welded joints (DMWJs) of pressure vessels, specifically focusing on SA508-III- 309L/308L-316L joints. Using the J-integral method, the research evaluates the impact of temperature on unstable crack propagation by conducting tests at varying temperatures, revealing that the JQ decreases as temperature increases, with a maximum reduction of 31.8%. The study concludes that the structural characteristics of the isolation layer and the thermal expansion differences exacerbate crack initiation and propagation, ultimately compromising the toughness of the weld material.

10 - Explosive Charge Applications in Seabed Strengthening for Underwater Pipelines

Authors: Eligiusz Mieloszyk, Anita Milewska, Mariusz Wyroslak This paper highlights the critical role of subsoil quality in ensuring the safety and reliability of underwater pipelines. It applies non-classical operational analysis to formulate a generalized dynamic system framework, within which the subsoil–pipeline interaction in underwater excavations is modeled. The study justifies using this analytical framework for the pipeline–subsoil system and proposes an innovative blasting-based method to compact and enhance subsoil for pipeline foundations.

16 - Corrosion prediction for shale gas pipelines based on Bayesian network and common cause failure analysis

Authors: Jianhua Gong, Jun Shen, Ming Wen, Kege Yang, Jing Zhou, Yaping Li, and Xingyu Zhu Internal corrosion causes perforation accidents in shale gas pipelines, with limited research on prediction due to complexity. This paper develops a Bayesian network model with common cause failure analysis to predict internal corrosion probability. Applied to a Sichuan Province shale gas field, the model achieved a 20% error margin against field inspections.

25 - Water Basin Effect of Cofferdam Foundation Pit

Authors: Guofeng Li, Qinchao Zuo, Xiaoyan Zhou, Yanbo Hu, and Ning Li This study examines the water basin effect in underwater sand layers of steel pipe pile cofferdams by applying foundation pit analysis concepts. It derives theoretical equations for deformation evolution of steel pipe piles and bottom seals during four dewatering stages: riverbed excavation, dewatering to second and third supports, and final sealing. Steel pipe piles are modeled as cantilever beams, and bottom seals as end-fixed beams, with deflection equations derived using superposition.

35 - Optimization Design Method of Pipe-Insulating Joints Based on Surrogate Model and Genetic Algorithm

Authors: Chen Guo, Zheng Yang, Jianbo Dong, Yanchao Yue, Linjun Tian, & Ping Ma This study addresses the over-conservative design of pipe- insulating joints in oil and gas pipelines, which leads to excessive size, weight, and cost. By analyzing the right flange under worst-case conditions and using finite element calculations, a dataset linking flange dimensions to maximum stress was generated. A surrogate model, developed via ridge regression, accurately predicts stress, enabling optimization. Coupled with a genetic algorithm, the model identifies optimal flange dimensions, reducing computational effort.

36 - A Transfer Matrix Method to Dynamic Calculation and Optimal Design of Flanged Pipelines

Authors: Zhiming Yang, Yingbo Diao, Jingfeng Gong, and Kai Gao This paper studies the dynamic characteristics of fluid-filled ship piping systems with flanges and optimizes their design using transfer matrix methods (TMMs). It proposes two modeling approaches for flat-welded and weld-neck flanges: Method 1 uses a lumped mass equivalent, while Method 2 equates flanges to pipe sections with increased wall thickness based on finite element and analogy concepts. Comparisons with finite element method (FEM) results show Method 2 is more accurate for both flange types. Experimental verification confirms consistency with Method 2.

50 - Progress in Offshore Oilfield Development Planning

Author: L.M.R. Silva, and C. Guedes Soares This article critically reviews the growing integration of ROVs and AUVs into offshore wind farm O&M, highlighting their role in enhancing safety, precision, and autonomy in harsh marine environments. It emphasizes synergies with AI, digital twins, and multi-robot collaboration, signaling a shift from crewed vessel- dependent, manual methods toward automated, sustainable, and integrated solutions aligned with the sector’s environmental and social goals. Key challenges, particularly energy autonomy, are discussed alongside emerging trends, underscoring the need for a robust, connected, and sustainability-driven offshore maintenance framework.

43 - Risk and safety assessment of hydrogen pipelines and storage tanks using preliminary hazard analysis

Authors: Solomon Asante-Okyere, Rhoda Afriyie Mensah, Joakim Sandström, and Michael Försth This study assessed hazards in hydrogen pipelines and storage tanks using a database, which recorded 34 pipeline and 28 storage tank incidents over five decades. Pipeline incidents frequently resulted in fires, while storage tank failures often led to explosions. Key hazards included corrosion and welding issues for pipelines, operational failures and corrosion for storage tanks, and rare but high- impact risks like natural disasters. Civil/construction work also posed risks to pipelines. The findings underscore critical vulnerabilities in these systems and emphasize the need for enhanced safety management to mitigate hazardous outcomes.

44 - Numerical study of corrosion in high pressure vent pipelines at high sulfur natural gas stations considering liquid phase accumulation and erosion

Authors: Jing Li, Jun Shen, Longhua Tan, Liang Zhang, Defei Du, Yihong Liao, and Xingyu Zhu Vent pipelines in high-sulfur natural gas stations are susceptible to acidic corrosion and erosion, particularly at elbows, compromising safety. Existing on-site wall thickness measurements are insufficient for accurately assessing the entire pipeline's corrosion status. This study employed computational fluid dynamics (CFD) to simulate a high-pressure vent pipeline. By analyzing the flow field, the simulation identified areas of liquid accumulation and severe erosion, providing data to guide on-site corrosion measurement point selection.

45 - Machine Learning Approaches for Fatigue Life Prediction of Steel and Feature Importance Analyses

Authors: Babak Naeim, Ali Javadzade Khiavi, Erfan Khajavi, Amir Reza Taghavi Khanghah, Ali Asgari, Reza Taghipour, and Mohsen Bagheri Predicting fatigue behavior in steel components is difficult due to nonlinear material degradation under cyclic loading. This study developed four hybrid machine learning models by combining Histogram Gradient Boosting (HGB) and Categorical Gradient Boosting (CAT) with metaheuristic optimization algorithms, Prairie Dog Optimization (PDO) and Wild Geese Algorithm (WGA). The models, HGPD, HGGW, CAPD, and CAGW, aim to improve the accuracy, generalization, and robustness of steel fatigue life predictions.

46 - Influence of Pile Spacing on the Compressive Performance and Soil Failure Mechanism of CEP Double Piles

Authors: Yongmei Qian, Yuhang Li, Xihui Wang, Yu Dong, Yingtao Zhang, Ming Guan, and Ying Zhou Concrete expanded-plate piles (CEP piles) are innovative variable-section piles that provide broader applicability, higher bearing capacity, and greater economic benefits than conventional straight-shaft piles, as evidenced by their growing adoption in construction. While prior research confirms the superior bearing performance of CEP monopiles, the impact of pile spacing on CEP double piles remains unexamined. This study addresses this gap by integrating small-scale soil tests with finite element simulations to assess how pile spacing affects the bearing behavior and soil failure mechanisms of CEP double piles.

47 - Re-evaluation of excavation class limits for underground excavations based on new data

Authors: Zulfu Gurocak, Ayberk Kaya, Mustafa Kanik, & Selcuk Alemdag Researchers have developed empirical excavatability classifications primarily for surface excavations, with limited options for underground conditions. This study analyzed 16 underground rock masses, assessing their engineering properties, rock strength, and in-situ excavation classes. Findings reveal that surface-based classifications are unsuitable for underground use due to overburden stress, which complicates excavation, particularly for medium, weak, and very weak rock masses. However, classifications align well for good to very good rock masses.

49 - Experimental study on critical conditions of ground collapse caused by leakage of pressurized hydraulic pipelines in sandy formations

Authors: Liling Zhou, Qimeng Ping, Huizhen Shen, Yiming Wang, Qing Huang, and Dazheng Zhang Ground collapse, a major safety risk, is often triggered by pipeline leakage in sandy formations. Through physical experiments, researchers identified three states of sandy formations under leakage erosion: infiltration disturbance, stable cavity, and fluidized failure. Critical conditions between stable cavity and fluidized failure were determined to predict ground collapse. Additionally, models were developed to predict collapse scale (volume/area) and provide early warnings based on surface subsidence and cavity area correlations. These findings offer a scientific basis for urban ground collapse prevention and control.

48 - A comprehensive risk assessment method for Christmas tree combined with a multi source information fusion algorithm and an improved HAZOP method

Authors: Qiong Wang, Huimin Li, Guanlong Ren This study introduces a novel risk assessment method combining an improved HAZOP technique with Genetic Algorithm (GA) and Backpropagation (BP) neural network techniques, first applied to offshore oil equipment, to evaluate safety risks of China’s first domestically produced subsea Christmas tree. Using multi-source fused risk data from installation and operation, the method classifies risk likelihood and severity.

51 - Remotely Operated and Autonomous Underwater Vehicles in Offshore Wind Farms: A Review on Applications, Challenges, and Sustainability Perspectives

Authors: Rodolfo Augusto Kanashiro, Juliani Chico Piai Paiva, Willian Ricardo Bispo Murbak Nunes, and Leonimer Flávio de Melo This study analyzes approximately 100 papers to identify methods for planning offshore oilfield development, aiding decision-making. Unlike previous reviews, it adopts a broad approach, not limited to a single methodology or oilfield characteristics. Key findings include the growing importance of environmental planning decisions and the crucial need to incorporate safety criteria into technical- economic decisions during the design phase of production systems.

07 - The Development of the Pipe Jacking Guidance Technology

Authors: Di Qiu, Lu Wang, Yutong Zu and Yin Qing Pipe jacking guidance collects machine attitude and position data to keep routes accurate within tolerances, preventing facility damage while boosting efficiency, precision, and safety. This paper reviews system principles and modes, classifies current techniques, surveys research, discusses trends toward automation, intelligence, and multi-source fusion, and outlines challenges in complex scenarios to guide further innovation.

08 - Mechanical Analysis of Lined Pipe System Under temperature– Pressure Coupling in Elastic Laying

Authors: Junyan Liu, Wei Zhang, Tianping Gu, Ju Liu, Jianxin Peng, and Yihua Dou Lined pipes are important for oil and gas transport because they resist corrosion and are cost-effective. Current design codes often simplify their behavior by viewing them as single-layer systems, ignoring the complex interactions between the liner and outer pipes when temperature and pressure change. This study creates a finite element model to assess the stress distribution and bonding strength of a specific lined pipe under various conditions. Findings reveal that internal pressure improves bonding strength and reduces delamination risk. Simplified models can underestimate stress interactions. This research highlights the need for better design methods.

09 - Identifying path ahead for tackling future challenges in direct- drive permanent magnet wind turbine generator’s electro- mechanical design and manufacturing

Authors: Abbas Mehrad Kazemi Amiri, Kelly Tartt, Alasdair McDonald To meet UK/EU Net Zero targets, offshore wind farms with larger turbines are expanding. Harsh conditions require reliable direct-drive permanent magnet generators, which avoid gearbox issues but are larger, heavier, and use more rare earths, creating OEM challenges in design, supply, manufacturing and installation. Reviewing state-of-the-art DDPM generators, identifying key OEMs and interviewing experts shows manufacturing scaling is the primary challenge. Recommendations include reducing magnet material, optimising structural mass, automating processes and adopting additive manufacturing.

24 - Offshore renewable energies: exploring floating modular energy Islands, materials, construction technologies, and life cycle Assessment

Authors: Enzo Marino et al. (29 co-authors) Floating modular energy islands (FMEIs) are interconnected floating structures that produce, store, convert, and transport renewable energy in offshore environments. This review examines existing technologies for floating energy structures and their applicability to FMEIs, evaluates suitable structural materials for construction, assesses appropriate offshore construction methods, and analyzes life cycle assessments of hybrid energy systems. The findings demonstrate environmental benefits of integrating multiple renewable energy sources, highlighting FMEIs' potential as sustainable multi-energy solutions.

33 - Influence of the Centre Distance between Counter-Rotating Control Rods and the Circular Cylinder on FIV Suppression

Authors: Tianqi Zhang, Zhaoyong Mao, Wenlong Tian, WenJun Ding, and Guanyong Yang This study uses computational fluid dynamics (CFD) to analyze flow-induced vibration (FIV) suppression in ocean engineering. The research examines how varying the distance between control rods and a main cylinder affects vibration suppression across reduced velocities of 2-14, with particular focus on transverse flow amplitude and lift coefficients at reduced velocity 10. Analysis of vorticity and pressure fields reveals that control rods suppress vibrations by disrupting wake vortices and reducing negative pressure in the wake region. enhanced suppression at high reduced velocities.

34 - Dynamic Analysis of an Offshore Knuckle-Boom Crane Under Different Load Applications Laws

Authors: Ivan Tomasi, and Luigi Solazzi This study analyzes the dynamic behavior of an articulated boom offshore crane using FEM simulations. Key resonance frequencies were identified in the direction of load application. The crane's response (displacement, velocity, acceleration) depends on load application laws, particularly the time (epsilon) to reach full payload. A strong exponential correlation exists between epsilon and the dynamic factor (maximum acceleration × payload), which influences structural effects like overstress, overturning, and buckling. This correlation serves as a tool to enhance the safety and reliability of offshore lifting operations.

52 - De-risking utilising a floating crane for floating offshore wind turbine maintenance

Authors: Alastair Ramsay, Vahid Vaziri, Sean Snee, Marcin Kapitaniak This study investigates the feasibility of in-situ generator replacement on the UMaine VolturnUS-S semi- submersible floating offshore wind turbine (15 MW) using a floating crane. Marine simulations at NDC assessed dynamic responses of the generator, nacelle, and crane barge across sea states. Results show that collision risk between the generator and turbine structure—not acceleration alone—is the primary operational constraint during lifting. Critical wave periods were identified that worsen motion and collision likelihood; lifting method adjustments had little effect, but aligning the crane barge parallel to incoming waves modestly reduced collisions.

53 - Flight Altitude of Common Cranes (Grus grus) Crossing the Arkona Basin (Baltic Sea): Implications for Offshore Wind Farm Development

Authors: Henrik Skov, Stefan Heinänen, Lars O. Mortensen, Johan Månsson, Lovisa Nilsson, Rune S. Tjørnløv, Ramunas Zydelis The study examines the potential interactions between migrating common cranes and offshore wind turbines in the Arkona Basin, a region slated for extensive wind farm development covering about 80% of the crane migration corridor. Using laser rangefinder tracking and GPS tagging, the research analyzed crane flight behavior in relation to weather conditions. Models showed that crane flight altitudes significantly depend on wind and sky clarity. During migration, cranes use coastal thermal winds to soar above 300 metres but descend to rotor height in the central basin under crosswind, headwind, and low clarity conditions.