Seminar - B. Mutlu Sumer - Pipeline floatation in liquefied soils under waves, and a brief description of EU research program LIMAS (Liquefaction around Marine Structures)
Friday, November 19, 2004, 1.10 - 1.50 pm
Civil Engineering Lecture Room 3
This talk consists of two parts.
The first part will summarize the results of an experimental and theoretical investigation of (1) the critical pipeline floatation in a soil (liquefied under waves) and (2) the density of the liquefied soil. In the experiments, the soil was silt with d50 = 0.078 mm. Pipeline models of 2 cm diameter (with different specific gravity) were used. Waves (with 17 cm wave height and 1.6 s wave period, the water depth being 42 cm) were used to liquefy the soil. The pipes with specific gravity smaller than 1.85 (near the bed surface) - 2.0 (near the impermeable base) floated when the soil was liquefied. A hydrodynamic model has been developed to predict the density of liquefied soil. The model is based on the force balance (in the vertical direction) for a soil grain settling in the liquefied soil.
The second part will describe LIMAS, a 3-year research program supported by EU; LIMAS (Liquefaction around Marine Structures (http://vb.mek.dtu.dk/research/limas/limas.html). The program has been undertaken by a consortium of 10 European institutions (universities, hydraulic and geotechnical engineering laboratories and consulting companies). In the presentation, a brief description of LIMAS will be given, highlighting the objectives of more than ten sub-projects under the program, focusing on different aspects of liquefaction of marine soils. The major part of the program concerns the wave-induced liquefaction although the seismic-induced liquefaction is also studied with regard to its impact on marine structures.