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Experiments
What kind of tests?
Micro instability
GEFtools
Anchor chain tests
Toelichting
Test 1
Test 2
Test 3
Test 4
Prediction

Anchor chain tests

Introduction

The intention for the anchor chain tests is to measure the penetration and forces of an anchor chain into a cover layer of a pipe line. Usually a pipe line is protected by a berm, build of broken rock. The pipe line is protected against buckling and by damage caused by anchoring vessels.  The required tickness of the cover layer is mainly the result of years of working experience, staying on the safe side. No fundamental knowledge of the cutting process is used, when designing the thickness of the cover layer.

Purpose of the tests

The purpose of the tests is to gain insight in the damage which a anchor chain might produce, when the chain is drawn through the cover layer.  The tests will be done in Geodelfts Geocentrifuge. A model of a cover layer is scaled 1:50. The actual cover in the real world will be 4 m high. Since the tests will be done at 50 g (50 times the standard accelleration of gravity), the model is just 8 cm high. Due to the 50 times higher accelleration of gravity the stresses in the layer are the same as in a layer in the real world.

http://www.geodelft.com/images/anker_alg.jpg

The berm at the exit side of the anchor chain.

http://www.geodelft.com/images/anker_top_view.jpg

Top view of the berm

Test series

It is our intention to perform four tests. In these tests certain aspects of the damage to the berm will be investigated.

Test 1. The first test was performed on July 1th. Its aim was to gain basic knowledge of the cutting process, i.e. the amout of friction between the anchor chain and the berm, the amount of damage to the berm. The force in the chain is roughly 350 N. Description is in Dutch.

Test 2. This test will be performed on July 6th. The tension in the anchor chain is half the value of the tension in test 1, 180 N. Description is in Dutch.

Test 3. This test has been performed on July 11th. The difference between earlier tests is that the Ng level is twice as high: 100. The force in the chain is roughly 350 N. Description is in Dutch.

Test 4. This test has been performed on Wednesday July 20th. In this test the size of the stones in the embankment will be twice as large as in earlier tests. The Ng level is 50. The force in the chain is roughly 350 N. Description in Dutch.