6.17 Wave induced instability of sand

A centrifuge wave test with progressive wave generating system was performed at Kyoto University (Sekiguchi, Kita et al.1996)

The objective of the test was to investigate geo-hazards in waterfront areas that might be induced by storm waves, tsunamis or rapid tidal changes shown in Fig. 1.

Schematic of the wave tank is shown in Fig. 2 and Photo 1.

The wave tank consisted of a wave channel, a wave paddle, a sediment trench and a slotted vertical partition that was placed in the wave channel.

The features of the slotted vertical partition as a wave absorber are schematically shown in Fig. 3.

The mechanical system that drives the wave paddle is shown in Fig. 4.

The frequency of the excitation of the wave paddle (or frequency) can be specified by tuning a controller in a range from 0 to 13 Hz.

When tested under a centrifugal acceleration of 50 G, wave frequencies of this range correspond to wave frequencies of 0 to 0.26 Hz on a prototype scale.

Test set-up for measuring the response of sand beds to progressive fluid waves is shown in Fig. 5.

Some of test results are shown in Fig. 6.

 

Fig. 1 Geohazards in waterfronts associated with storm or rapid tidal changes

 

Fig. 2 Cross section of the wave tank

 

 

 
Photo 1 Schematic of the wave tank

 

Fig. 3 Slotted vertical partition as a wave

Fig. 4 Wave-paddle driving system

Fig. 5 Test set-up for measuring the response of sand beds to progressive waves

 

Fig. 6 Measured performance in wave test

 

Reference

Sekiguchi, H., Kita, K., Sassa, S. and Shimamura, T. (1996) : Development of progressive-wave generating systems in a balanced-beam centrifuge, Annuals, DPRI, Kyoto Univ., No. 39, B-2.