30 / 2025-04-24 11:27:32

Parameter study of factors influencing wave-induced liquefaction

Wave-induced liquefaction is a process that occurs, for example, in riverbeds and can lead to
sediment movement, destabilisation of bank protection measures or washout of submarine
pipelines due to the loss of load-bearing capacity of the soil. During this process, the behaviour
of the soil changes from solid-like to fluid-like, and up to a certain liquefaction depth, the state of
the soil can be described as a state of suspension. This change in behaviour is caused by excess
pore water pressure, generated for example by ship-induced waves, and a loading rate that is fast
compared to the pore pressure dissipation rate. In addition to these two parameters, the process
itself is influenced by water depth, wave height or degree of saturation.
A numerical simulation of liquefaction must take into account non-constant parameters such as
permeability, a strong hydro-mechanical coupling and, in the case of large movements, a
kinematic description allowing finite deformation. Within the FEniCS framework, a hydro
mechanical model has been constructed that is able to capture large deformations and flexible
constitutive approaches. The overall aim is to develop a framework including constitutive
approaches that allows to capture the phase change in both directions. The underlying hydro
mechanical model will be explained, including the large strain setting and the constitutive
approaches describing fluid compressibility, permeability-porosity dependence and the stress
strain relation. A comparison with experimental data sets generated in a soil column in
combination with an alternating flow apparatus will show the agreement between experimental
results and the numerical simulation. Additionally, Julia Rothschink submitted an abstract on a
paper Soil liquefaction triggered by ship waves in rivers and canals – A laboratory investigation
on fine sands, where she will explain the experimental investigations that are used for
comparison with these numerical simulations.
The results of the numerical simulation are influenced by the input variables derived from the
experimental set-up. It is necessary to investigate how much the uncertainty of the input
parameters influences the results of the numerical simulation. The results of a parameter study
will be shown, explaining the extent of the dependency between the uncertainty of the input
parameters and the numerical result. These input parameters include the stiffness, temperature,
degree of saturation, permeability and porosity