Installation of marine structures by suction - hydro-mechanical coupled numerical modelling

该研究项目的目的是研究吸力桶/吸力沉箱的安装过程，吸力桶/吸力沉箱通过施加吸力进入由饱和砂土或层状土壤组成的海床。研究了安装过程中的承载特性，以及在超压支撑下将吊桶从海床中抽出的过程。在已有的土工离心机模型试验的基础上，研究了土工离心机在土工离心机上安装、承载和抽取过程中土体的排水特性。用数值方法研究了其安装、拔出过程和承载性能。因此，可以更好地了解土体中的机械-水力耦合过程，并研究安装过程对承载性能的影响。将该研究所现有的一种方法推广应用于饱和砂土和层状地基中的耦合力学水力学行为的研究，因此，采用有限元方法对其承载特性进行了模拟。此外，还利用材料点法(MPM)对安装过程进行了模拟。由于我们研究所提供了MPM源代码，因此针对任何特定问题的程序修改和扩展都是可行的。验证了用于模拟安装的MPM模型和用于模拟承载行为的有限元模型，并将其应用于参数研究以考察不同的影响。

The objective of the research project is the investigation of the installation process of suction buckets/suction caissons, which penetrate by application of suction into the seabed consisting of saturated sand or layered soil. The load bearing behaviour with respect to the installation process is investigated as well as the process of extraction of the bucket out of the seabed supported by excess pressure. Building on results of existing model tests of the process of installation and extraction as well as the load bearing behaviour, additional model tests in a geotechnical centrifuge are performed to investigate the drainage behaviour of the soil during the installation, load bearing and extraction. The process of installation and extraction and the load bearing behaviour is also investigated through numerical methods. Therefore, the coupled mechanical hydraulically processes in the soil are better understood and the influence of the installation process on the load bearing behaviour is investigated. An approach, which is existing at the institute, is extended and utilised for investigations on the coupled mechanical hydraulically behaviour in saturated sand and layered soil Therefore, the Finite Element Method (FEM) is utilised for simulations of the load bearing behaviour. Furthermore, the Material-Point Method (MPM) is utilised for simulations of the installation process. Since the MPM-source-code is available at our institute, the program modifications and extensions for any specific problem are feasible. The MPM-models for the simulation of the installation and the FEM-models for the simulation of the load bearing behaviour are validated and applied for a parametric study to investigate different influences.