Seminar - Haijiang Liu - Coastal-related Marine Sediment Movement and Response
Wednesday, May 24, 2006, 1.10 - 1.50 pm
Civil Engineering Lecture Theatre 3
The whole presentation is twofold, which includes investigations on bottom sand particle movement under the sheetflow condition on one side and studies on the random wave-induced soil response on the other.
For the first part related to the sediment movement, relevant work has been conducted both from laboratory experiments and numerical simulations. The main objective of the study is to increase insight in cross-shore sand transport processes under sheetflow conditions. Experiments were performed using Oscillating Flow Tunnel at UT, and measurements on erosion depth, sediment concentration, sand velocity and turbulent structure were carried out by applying various measuring techniques, i.e., image analysis and PIV technique. As for the numerical simulation, a two-phase flow model of the state-of-the-art was set-up, which takes into account the grain-grain, grain-fluid interactions. Validation of the model was demonstrated on the time- and spatial-varying configurations of sediment concentration, velocity and sand flux as well as induced net transport rate through comprehensive comparisons with a large amount of up-to-date experimental data. Results highlight the applicability of the newly developed two-phase flow model.
Considering the second part corresponding to soil response, different from the existing work by utilizing monochromatic waves, the random wave-induced soil responses, e.g., pore wave pressure, effective normal stresses and shear stress, together with the liquefaction potential were investigated after applying two different random wave spectra, i.e., BM Spectrum and JONSWAP Spectrum. A semi-analytical solution was proposed for various soil responses. Effects on the soil response from several parameters, such as, soil permeability, soil saturation, wave height, wave period and soil depth, were conducted through parametric studies. Finally, the maximum liquefaction depth under the random waves was specified.
At last, the future perspectives are presented for the forthcoming studies.