Stability of artificial subaqueous slopes in sandy soils

在近海条件下建造人工海底深坑时，应考虑由于水动力作用(如水流、波浪、地震等)造成的长期倾斜小于岸上倾斜。我们的研究项目集中在非粘性土中海底边坡几何形状的变化(侵蚀、淤积、裂隙破坏、液化破坏)，表面波引起的超孔压导致有效应力降低，而对于海底边坡，边坡几何形状的变化取决于土体的波长L、波高H、水深h和渗透率k。在前期工作中，我们基于线性波动理论和线性拟静力固结理论的耦合对这一过程进行了研究。借助于数值模拟，我们求解了相应的方程，同时也考虑了材料的非线性固结。在研究项目的范围内，将对实验和理论研究进行验证。因此，将在模型航道中进行在H、L、h和k变化情况下的模型试验。采用两种不同的离散方法，即包括CEL算法的有限元方法和SPH方法来模拟海底斜坡上发生的重排过程。在选定的北海地点，将基于经过验证的数值模型来模拟用于海上风电场基础的典型海底斜坡的建造。

During the construction of artificial submarine pits under offshore conditions it should be considered that the long-term slope-inclination is less than onshore due to hydrodynamic actions (e. g. flow, waves, earthquakes). Our research project is focused on changes of geometry of submarine slopes in non-cohesive soils (erosion, sedimentation, breach failure, liquefaction failure) due to surface waves which cause excess pore water pressures leading to a reduction of effective stresses and in case of submarine slopes to changes of slope geometry depending on wave length L, wave height H, water depth h and permeability k of soil. During our preliminary work we investigated such processes based on the coupling of linear wave theory and linear quasi-static consolidation theory. With the help of numerical modelling we solved corresponding equations considering also materially nonlinear consolidation. Within the scope of the research project the experimental and theoretical investigations will be validated. Therefore model tests in a model channel will be carried out under variation of H, L, h, and k. Occurring rearrangement processes in the submarine slopes will be simulated using two different discretization methods, namely FEM including a CEL algorithm, as well as SPH. The construction of a typical submarine slope for foundation of an offshore wind park at a chosen North Sea site will be simulated based on validated numerical models.