STABILITY OF DOLOSSE WITH DIFFERENT WAIST THICKNESS FOR IRREGULAR WAVES

Model tests were done to investigate the effect of waist thickness on the stability of dolosse under irregular wave attack. A comprehensive test programme resulted in a better understanding of dolos behaviour under a wide range of different conditions. Irregular waves with Jonswap and Pierson- Moskowitz spectra were generated using a total of four different peak wave periods. Dolosse with five different waist ratios were tested. All the dolosse had a mass of about 80 g and were placed at a "normal" packing density of = 1,00. Tests were done on three different slopes namely 1:1,33, 1:1,5 and 1:2. The test results showed that the stability of dolosse decreases as the waist ratio is increased. On average, KD-values for 2 per cent displacement of dolosse with waist ratios of 0,36 0,38, 0,40 and 0,43 were approximately 22, 51, 49 and 69 per cent respectively smaller than the Ko-value of dolosse with a waist ratio of 0,33.