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Experiments
What kind of tests?
Micro instability
Test 3
Test 4
Test 5
Test 6
Test 7
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Anchor chain tests
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Micro instability

Micro instability on dikes is a phenomenon in which the lower part of a dike becomes instable due to seeping water. For sandy dikes it is a problem particularly when the water in a channel or river is high and when due to a lacking drainage facility the ground water table in the dike is sufficiently high to reach the inner slope. 

Test 1. In this test two slopes were tested, a slope of 1:3 and a steeper slope of 1:2. During this test the 1:2 slope suffered from most damage. When nearly the entire 1:2 slope was washed away, the 1:3.2 sloped suffered only minor damage. The g-level was 80, so the scale of the model was 1/80th part of the real dike. For a MPG movie, click on Short overview test 1

Test 2. In this test the possible influence of the g-level on the observed phenomena was tested. In this test the dike was scaled to a 1/40 part of the real dike. The g-level was subsequently lowered to 40. The slope was 1:2. Similar damage on the 1:2 slope occured compared to the first test.

Test 3. In this test the dike was again scaled to a 1/80th part of the real dike. A slope of 1:3.2 was chosen, since in the first test hardly any damage was found, compared to a 1:2 slope. 

Test 4. In this test the g-level is 80. In the toe of the dike a drain is applied. The slope of the dike is 1:2. The effect of the drain on micro instability is investigated.

Test 5. This test was done on Thursday, August 5th, 2004. The slope of the dike is 1:2. The core of the dike is made of sand. A top layer of clay will be applied, mimicing a cohesive and impervious layer. 

Test 6. This test was done on Thursday, August 19th, 2004. The slope of the dike is 1:2. The dike is made of sand. The scale in the test will be 1/20th part of the real world, at Ng = 20.

Test 7. The test will be done on Thursday, August 26th, 2004. The dike has two slopes, like in the first test: 1:2 and 1:3.3. The slopes are covered by a layer of soft clay. The Ng level is 80.