The Delft Sand, Clay & Rock Cutting Model, 2019a

Saturated Sand Cutting.
6.13. Experiments.
6.13.1. Description of the Test Facility.
The tests with the straight blades are performed on two locations:
1. The old laboratory of Dredging Engineering, which will be called the old laboratory DE.
2. The new laboratory of Dredging Engineering, which will be called the new laboratory DE.
The test stand in the old laboratory DE consists of a concrete tank, 30 m long, 2.5 m wide and 1.35 m high, filled
with a layer of 0.5 m sand with a d50 of 200 m and above the sand 0.6 m water. The test stand in the new laboratory
DE consists of a concrete tank, 33 m long, 3 m wide and internally 1.5 m high, with a layer of 0.7 m sand with a
d50 of 105 m and above the sand 0.6 m water. In both laboratories a main carriage can ride over the full length of
the tank, pulled by two steel cables. These steel cables are winded on the drums of a hydraulic winch, placed in
the basement and driven by a squirrel-cage motor of 35 kW in the old laboratory DE and 45 kW in the new
laboratory DE.
In the old laboratory DE the velocity of the carriage could be infinitely variable controlled from 0.05 m/s to 2.50
m/s, with a pulling force of 6 kN. In the new laboratory DE the drive is equipped with a hydraulic two-way valve,
which allows for the following speed ranges:
1. A range from 0.05 m/s to 1.40 m/s, with a maximum pulling force of 15 kN.
2. A range from 0.05 m/s to 2.50 m/s, with a maximum pulling force of 7.5 kN.
Figure 6-36: Side view of the old laboratory.
An auxiliary carriage, on which the blades are mounted, can be moved transverse of the longitudinal direction on
the main carriage. Hydraulic cylinders are used to adjust the cutting depth and to position the blades in the
transverse direction of the tank. Figure 6-36 shows a side view of the concrete tank with the winch drive in the
basement and Figure 6-37 shows a cross section with the mounting of cutter heads or the blades underneath the
auxiliary carriage (in the new laboratory DE). The main difference between the two laboratories is the side tank,
which was added to dump the material excavated. This way the water stays clean and under water video recordings
are much brighter. After a test the material excavated is sucked up by a dustpan dredge and put back in the main
tank. The old laboratory DE was removed in 1986, when the new laboratory was opened for research.
Unfortunately, the new laboratory stopped existing in 2005. Right now there are two such laboratories in the world,
one at Texas A&M University in College Station, Texas, USA and one at Hohai University, Changzhou, China.
Both laboratories were established around 2005.
Figure 6-38 and Figure 6-39 give an overview of both the old and the new laboratories DE, while Figure 6-40
shows a side view of the carriage, underneath which the blades are mounted.
Removing the spoil tank (3) from this figure gives a good impression of the cutting tank in the old laboratory DE.
Instead of a cutter head, blades are mounted under the frame (6) during the cutting tests.
Copyright © Dr.ir. S.A. Miedema TOC Page 161 of 454