Coupled micromechanical modelling for the analysis and prevention of erosion in hydraulic and offshore infrastructures

用于分析和预防水力和海上基础设施侵蚀的耦合微机械建模

• 批准号: 406907912
• 负责人: Dr.-Ing. Pablo Cuéllar
• 金额: --
• 依托单位: Abteilung 7: Bauwerkssicherheit
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/406907912?language=en
• 关键词: Coupled; micromechanical; modelling; analysis; prevention

The scope of this project concerns the water-flow erosion of geomaterials in relation to the failure of civil engineering infrastructures with large socio-economic relevance such as flood protection dykes and offshore wind-farm foundations. We aim to clarify the underlying mechanisms by which such systems are stressed by a fluid flow until a local dislocation is finally generated within the solid medium, leading to a material loss and eventually to the mechanical instability of the whole structure.For this, we want to bridge the gap between the micromechanical phenomena at the grain scale and the macromechanical application for engineering problems by developing efficient large-scale coupled simulation models that reproduce directly the interactions between a fluid phase and the bonded assembly of solid particles. To this end, we will couple relevant simulation techniques for the fluid and solid phases (the Lattice Boltzmann Method and the Discrete Element Method, respectively).We envisage a progressive development of representative models at different scales, at first on a meso-scale to reproduce local phenomena in small setups of our laboratory tests, and then increasing in size and complexity up to the real scale of the engineering problems. The models shall feature a solid contact scheme for intergranular cohesion and transient material damage, which are key elements that may govern the macromechanical failure modes of geotechnical systems. A key task at the development stage will be the adaption of our algorithms for parallel computation by means of graphical processors and clusters.A first field of application shall be the assessment of erosion in hydraulic constructions such as a river levee. In this respect, we will develop detailed micromechanical models of typical erodibility assessment scenarios and analyse the dependencies of the resulting parameters on the granular properties and geotechnical characterizations of the soil. The validated scenarios shall then be upscaled to simulate locally their real-scale counterparts within a practical levee erosion problem.In parallel, the second field of application concerns the foundation structures for offshore wind-turbines. A detailed assessment of different scouring scenarios shall provide a basis for optimized foundation designs and help reduce the costs of windfarm developments. Besides, promising innovative foundations in the offshore field, such as the Suction Buckets, are still not well established due to largely unresolved questions concerning their dual interaction to both the marine soil and the pore water. The stability of the suction mechanism as well as the possibility of a localized hydraulic failure (piping) of the buckets during their installation are key questions that will be addressed here. The development of the intended models dealing with such phenomena from a micromechanical perspective shall provide answers which have been missing in the offshore practice so far.

该项目的范围涉及与具有重大社会经济相关性的土木工程基础设施（例如防洪堤和海上风电场基础）的失效有关的岩土材料的水流侵蚀。我们的目标是阐明此类系统受到流体流动的压力，直到最终在固体介质内产生局部位错，从而导致材料损失并最终导致整个结构的机械不稳定的潜在机制。为此，我们希望通过开发有效的大规模耦合模拟模型，直接再现流体相和固体颗粒的键合组件之间的相互作用，弥合晶粒尺度的微观力学现象与工程问题的宏观力学应用之间的差距。为此，我们将结合流体和固相的相关模拟技术（分别是格子玻尔兹曼方法和离散元方法）。我们设想逐步开发不同尺度的代表性模型，首先在中观尺度上在我们实验室测试的小型装置中重现局部现象，然后增加规模和复杂性直至工程问题的实际规模。该模型应具有用于粒间粘聚力和瞬态材料损伤的固体接触方案，这是控制岩土系统宏观力学失效模式的关键要素。开发阶段的一项关键任务是通过图形处理器和集群来调整我们的算法以进行并行计算。第一个应用领域是评估水工建筑（例如河堤）的侵蚀。在这方面，我们将开发典型可蚀性评估场景的详细微力学模型，并分析所得参数对土壤颗粒特性和岩土特征的依赖性。然后，验证的场景将被放大，以在实际的堤坝侵蚀问题中本地模拟真实规模的对应场景。同时，第二个应用领域涉及海上风力涡轮机的基础结构。对不同冲刷场景的详细评估将为优化基础设计提供依据，并有助于降低风电场开发成本。此外，由于吸力桶与海洋土壤和孔隙水的双重相互作用的问题很大程度上尚未解决，海上领域有前途的创新基础（例如吸力桶）仍然没有得到很好的建立。抽吸机构的稳定性以及铲斗在安装过程中出现局部液压故障（管道）的可能性是这里要解决的关键问题。从微观机械角度处理此类现象的预期模型的开发将提供迄今为止在海上实践中缺失的答案。