Part C - Minimum Requirements on geotechnical investigations 
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2.2.2 Indirect explorations (Sounding and in-situ measurements) 
Cone penetration tests (CPT) in accordance with DIN EN ISO 22476-1 measure the cone tip 
resistance and local sleeve friction as a minimum requirement. In addition, pore water pres 
sure can be measured (CPTu) as well as other parameters (e. g. vane shear, boom tilt, and 
probe speed). 
CPT testing is either carried out in a continuous manner from the seabed (seabed CPT) or 
from a fixed working platform (topdrive CPT) or as a discontinuous probe from the borehole 
bottom (downhole CPT). Further guidelines and notes for carrying out and assessing cone 
penetration testing are contained in Lunne et al. (1997) inter alia. 
In the borehole dynamic penetration test (BDP) in accordance with DIN 4094-2 the sounding 
device is driven into the bottom of a borehole while counting the number of blows required 
A summary of other indirect investigation methods (vane shear, pressure meter, temperature 
probes, borehole geophysics, etc.) is provided by e. g. DIN EN ISO 19901-8 or Balthes et al. 
(2005). 
2.2.3 Soil and rock sampling 
The geotechnical expert determines the frequency of sampling depending on the foundation 
soil strata according to DIN 4020. Certain offshore conditions should be taken into account 
according to e. g., Fugro-McClelland Ltd. (1993), McClelland & Reifel [1986], API RP 2A-WSD, 
DNV-OS-J101, DNV Classification Notes No. 30.4 or DIN EN ISO 19901 -8. 
The drilling methods and the extraction unit for loose rock (soils) must correspond to sampling 
category A in accordance with DIN EN ISO 22475-1 and should be selected such that in case 
of cohesive soils samples of at least grade 2 and as many grade 1 samples can be obtained 
as possible. The sediment samples must be undisturbed at least in their composition, water 
content, density, and permeability. 
If grade 1 or 2 samples cannot be achieved using available drilling methods in cohesive soils, 
there is a possibility of taking sediment samples from the borehole bottom with a suitable ex 
traction unit corresponding to sampling category A in accordance with DIN EN ISO 22475-1. 
It has been found that thin wall tube samplers (wall thickness 2 mm) are the most suitable tool 
for taking soil samples both from normally consolidated cohesive soils. Conventional Shelby 
tubes orthin-wall samplers are preferably used for this purpose. Samples are preferably taken 
as push samples. 
Overconsolidated cohesive soils can be sampled using special thick-walled samplers (wall 
thickness 4.5 mm); either push or hammer samples can be taken with this method. 
In case of non-cohesive soils, sediment samples of at least grade 4 must be obtained, which 
remain unchanged with regard to their composition. Obtaining sediment samples which are at 
least grade 3 is targeted for non-cohesive soils. In case of core-compatible non-cohesive 
soils, driving and/or rotating drilling processes with or without a rinsing aid which steadily 
gains core soil samples in accordance with DIN EN ISO 22475-1 can be used. 
The drilling procedure for solid rock (rock and solidified loose rocks) should be selected such 
that with a category A sampling process in accordance with DIN EN ISO 22475-1 sediment 
cores can be obtained that are at least grade 2. The core barrel drilling process with double or 
triple tube is especially suitable for sampling in solid rock.