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

The Properties of the 200 μm Sand.
Appendix K: The Properties of the 200 μm Sand.
The sand in the old laboratory DE, with a d50 of 200 m, is examined for the following soil mechanical parameters:
1. The minimum and the maximum density, Table K-1: Pore percentages.
2. The dry critical density, Table K-1: Pore percentages.
3. The saturated critical density, Table K-1: Pore percentages. The permeability as a function of the density,
Table K-2: Permeability as a function of the porosity.
4. The angle of internal friction as a function of the density, Table K-4: The angle of internal friction as function
of the pore percentage.
5. The d50 as a function of the time, Table K-3: The d 50 of the sand as function of the time.
6. The cone resistance per experiment.
7. The density in the test stand in combination with the cone resistance.
The points 7 and 8 need some explanation. With the aid of a Troxler density measuring set density measurements
are performed in situ, that is in the test stand. During each measurement the cone resistance is determined at the
same position. In this way it is possible to formulate a calibration formula for the density as a function of the cone
resistance. The result is:
65.6
n with: n in %, C in kPa
0.082
p
(K-1)
Cp
In which the cone resistance is determined in a top layer of 18 cm, where the cone resistance was continuously
increasing and almost proportional with the depth. The value to be used in this equation is the cone resistance for
the 18 cm depth.
With the aid of this equation it was possible to determine the density for each cutting test from the cone resistance
measurements. The result was an average pore percentage of 38.53% over 367 tests.
By interpolating in Table K-2 it can be derived that a pore percentage of 38.53% corresponds to a permeability of
0.000165 m/s. By extrapolating in this table it can also be derived that the maximum pore percentage of 43.8%
corresponds to a permeability of approximately 0.00032 m/s. At the start of the cutting tests the pore percentage
was averaged 38%, which corresponds to a permeability of 0.00012 m/s.
Copyright © Dr.ir. S.A. Miedema TOC Page K-49 of 228