Empirical research for the hydraulic stability of rock-filled mesh bags in offshore application for the stabilisation of cable protection systems

The expanding offshore wind industry is facing challenges with excessive movement of the power cables that connect offshore turbines to the grid. The casings that surround the exposed parts of cables near structures, known as cable protection systems (CPS), show damage before the end of their expected service life, requiring costly repair and maintenance. A potential solution is to stabilise the CPS by placing one or more rock-filled mesh bag (rock bag) on top of it. There are multiple rock bag manufacturers and distributors. The bags are made of polyester netting that is relatively flexible. The sizes considered for this study are 4 and 8 ton (4000 and 8000 kg), but smaller and larger sizes are available. Currently, little is known about the behaviour and stability of these rock bags in offshore environments. The goal of this study is to expand the knowledge through empirical model testing.480 experiments were conducted in a flume in the hydraulic engineering laboratory of Delft University of Technology. Two set-ups were used, one with a flat rough bed, to test two or three rock bags side by side and grouped formations of bags. The other is a realistic halved model of a monopile, scour protection and CPS. Regular wave, irregular wave and combined wave-current conditions have been tested.Analysis of before and after top images of the tests is used to establish a failure criterion. The test results are compared to the empirical stability limit defined by Jacobsen et al. (2023). In this way, a stability limit applicable for irregular wave fields is found. The effects of grouping and near monopile flow amplification are quantified. Internal friction is found to be a relevant parameter that should be considered in physical model studies.This data serves to back up all conclusions reached in the experiments and allows for changing the stability calculations by providing all relevant inputs. All libraries, scripts and processed data are provided. As well as all processed top pictures.Notebooks:-       WaveCurrent_irr.ipynbAnalysis of irregular tests with combined wave current-       Results_analysis_irregular.ipynbAnalysis of irregular wave tests-       Results_analysis_regular.ipynbAnalysis of regular wave tests-       Regular_v2.ipynbOutput: Dataframe with caracteristic values to describe each test used as input for analysis of regular wave tests-       Toppictures_analysis.ipynbProcess of top pictures for analysis<strong>Libraries:</strong>-       Fenton-       decomp_lib<strong>Sheets:</strong>-       Master table and data-       glass_pros-       grouped_pros-       lightmaterial_pros-       regular_waves_pros

快速扩张的海上风电行业正面临着将海上风机与电网相连的电力电缆过度位移的难题。安装在结构附近电缆裸露段外围的防护套管，即电缆保护系统（Cable Protection Systems，简称CPS），往往在预期使用寿命到期前就出现损坏，需要投入高额成本进行维修与养护。
一种潜在的解决方案是在CPS上方放置一个或多个填石网袋（简称石袋）以稳定其结构。目前市场上有多家石袋制造商与分销商，这类网袋采用相对柔韧的聚酯网制成。本研究考量的规格为4吨和8吨（即4000千克与8000千克），不过也有更小或更大的尺寸可供选择。
当前，学界对这类石袋在海洋环境中的工作特性与稳定性尚缺乏足够认知，本研究旨在通过经验模型试验拓展相关研究认知。研究团队在代尔夫特理工大学水利工程实验室的水槽中开展了共计480组试验。试验采用两种布置方案：其一为平整粗糙床面，用于测试并排摆放的2~3个石袋以及石袋的群组布置形式；其二为包含单桩基础、冲刷防护与CPS的半尺寸真实模型。试验覆盖了规则波、不规则波以及波流联合作用三种工况。
通过对试验前后的俯视图像进行分析，研究人员确立了石袋失效判定准则。将试验结果与Jacobsen等人（2023）提出的经验性稳定极限进行对比，最终得到了适用于不规则波场的稳定极限公式。同时量化了石袋群组布置效应以及单桩附近水流放大效应的影响，研究发现内部摩擦是物理模型试验中需要考虑的关键参数。
本数据集可支撑试验得出的全部结论，并通过提供所有相关输入参数支持稳定性计算的迭代优化。研究团队公开了全部代码库、脚本文件、经处理的试验数据，以及所有经过预处理的俯视图像。
Notebooks:
-       WaveCurrent_irr.ipynb：波流联合工况下不规则波试验分析
-       Results_analysis_irregular.ipynb：不规则波试验结果分析
-       Results_analysis_regular.ipynb：规则波试验结果分析
-       Regular_v2.ipynb：输出用于规则波试验分析的特征值数据框
-       Toppictures_analysis.ipynb：用于试验分析的俯视图像处理流程
<strong>Libraries:</strong>
-       Fenton
-       decomp_lib
<strong>Sheets:</strong>
-       Master table and data：总表与原始数据
-       glass_pros：玻璃试件组数据
-       grouped_pros：群组布置试件组数据
-       lightmaterial_pros：轻质材料试件组数据
-       regular_waves_pros：规则波试验组数据