Impulse waves in reservoirs, lakes, bays and oceans may be generated by
landslides. The resulting impulse waves can propagate and cause disaster to the
downstream. Some studies are carried out to investigate such phenomenon but
most of them were based on either experimental observations or empirical/semiempirical
relationships in simulating the waves generated by landslides. Therefore,
the fundamental mechanism of such hazard is not got fully understood (complex
motions of landslides with arbitrary geometry and interactions of fluid with
landslides or shorelines). In addition, the effects of landslide-induced waves on
downstream structures are rarely reported. Therefore, it appears necessary that the
coupling numerical model is developed to simulate landslide-induced waves and
to investigate generated wave characteristics. Furthermore, their effects on
downstream structures should be investigated for mitigating hazard, such as the
estimations of wave run-up, rundown and wave overtopping.
This thesis presents the numerical modeling of landslide-induced waves and their
effects on the downstream structures based on the computational fluid dynamics
(CFD) package FLUENT. As there is no existing module to simulate water waves,
the redevelopment of FLUENT by the user defined function (UDF) is necessary.
For the problem of landslide-induced wave, two simplified numerical models are
developed, including piston-type model and inlet boundary-type model. These two
numerical models can rapidly assess the landslide-induced waves but be
appropriate for the simple cases, such as a vertical wall moving horizontally or
slump-type landslide whose particle velocities and free surface displacements at
the inlet boundary are known. In order to expand the available range of numerical
modeling, the block models aiming for rockslide are developed to investigate
landslide-induced waves. Four categories of landslides are considered, such as
horizontal landslide, vertical landslide, subaerial landslide and submarine
landslide. Except of horizontal landslide, the coupled block model is employed to
investigate water waves generated by vertical, subaerial and submarine landslides.
The coupling is based on an iterative procedure enforcing the principle of the
dynamic equilibrium of the fluid, the slide and their interfaces, and the interaction
between landslide and fluid are considered. The wave characteristics generated by
above-mentioned different types of landslides are investigated and discussed. For
their effects of landslide-induced wave on downstream structures, the focuses of
numerical modeling are the run-up and rundown of waves generated by subaerial
and submarine landslides and wave overtopping on the downstream structures.
The detailed numerical modeling illustrates that the present models can predict
fairly well landslide-induced waves and their effects on downstream structures.
The results of parametric study indicate that slide volume and impact Froude
number ( v / gh ) play important roles on generated wave characteristics. The
wave characteristics, propagation distance and geometric characteristics of
seaward structural wall (slope and crest freeboard) are major factors in
determining the characteristics of wave run-up, rundown and overtopping. Several
useful prediction relationships are provided. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/167217 |
| Date | January 2012 |
| Creators | Liu, Xia, 刘霞 |
| Contributors | Tham, LG |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B48199412 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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