Kriegers Flak Offshore Wind Farm
Geo Investigations 2013
Factual Report – Seabed CPTs and Geotechnical Boreholes
GEO project no 36642
Report 1, 2013-10-30
Summary
Energinet.dk has contracted SSE AB to conduct a geotechnical site investigation at the
planned Kriegers Flak Offshore Wind Farm site. SSE AB has sub-contracted GEO to perform the technical investigation.
The overall objective of the present preliminary geotechnical investigation of the Kriegers
Flak area is to collect geological and geotechnical information for a later evaluation of the
foundation and installation conditions for the Offshore Wind Farm.
The present preliminary geotechnical investigation includes a seabed Piezo-cone penetration testing (CPT) campaign and a geotechnical borehole campaign. Down the hole CPTs
(DTH-CPT) were performed at all boreholes. The field investigations were carried out in
the period between 1st. May 2013 and 12th. June 2013.
A total of 67 deep push seabed CPTs were performed at 42 locations, where 17 of the
locations are at a borehole location and the remaining 25 locations are solely CPT location. The penetration depth of the seabed CPTs varied between 0.6 m and 26.7 m below
seabed with an average penetration of 13.7 m.
A total of 17 geotechnical boreholes were performed at 17 locations within the Kriegers
Flak Offshore Wind Farm site. At all 17 borehole locations there are also executed a seabed CPT test. 6 of the boreholes were drilled to the target depth 70 m below seabed and
11 of the boreholes were drilled to the target depth 50 m below seabed. DTH-CPTs were
performed in all boreholes and pressuremeter tests were performed in 4 of the boreholes.
All samples from the boreholes have been logged and photographed offshore. Various
classification-, chemical-, strength- and deformation tests have been executed on
selected samples.
The Danish part of the Kriegers Flak bank is composed of a rather complex sequence of glacial deposits, including Interstadial deposits (i.e. sediments from a
GEO
Maglebjergvej 2
DK-2800 Kgs. Lyngby
Tel: +45 4588 4444
Fax: +45 4588 2240
geo@geo.dk
www.geo.dk
GEO Project No 36642
Report 1, 2013-10-30Kriegers Flak
CVR-no: 59782822
short, warmer period within a glacial period), as well as Lateglacial and Postglacial deposits, all of which overly the Cretaceous Limestone.
The Postglacial and Lateglacial deposits consist of sand and clay and are in general less
than 4 metres thick. The deposits are generally loose/soft and have locally organic content (gyttja).
The glacial deposits mainly consist of stiff to very stiff clay till or dense to very dense
sand till and vary in thickness approximately between 20 m to 40 m. The till is generally
intersected by meltwater layers/lenses of clay and sand. At one position (KF-BH006) the
glacial deposits have not been penetrated 50 m below seabed.
Interstadial organic clay/peat has been identified in two boreholes (KF-BH004 and KFBH014). A C14 determination has dated this unit to 38400 years before present.
The Cretaceous Limestone is found in all boreholes except borehole KF-BH006. In the
entire area the Prequaternary bedrock is made of Maastrictian Limestone deposited during the Late Cretaceous period. This deposit occurs very widespread in NW-Europe, in
the Kriegers Flak area mainly as a muddy, white limestone with many nodules and thin
layers of dark grey/black flint. The upper part of the limestone is locally showing evidence of glacial deformation.
This Factual Report (Report 1) includes factual data and laboratory results from the investigations related to the seabed CPTs and the geotechnical boreholes at the Kriegers
Flak site.
GEO Project No 36642
Report 1, 2013-10-30Kriegers Flak
Prepared for
Prepared by
Energinet.dk
Mette Bakmand-Mikalski, +45 4520 4218, mbm@geo.dk
Tonne Kjærsvej 65
Louise Tranholm, +45 4520 4211, ltr@geo.dk
7000 Fredericia
Controlled by
Denmark
Lars Rasmussen, +45 4520 4179, lar@geo.dk
Contents
1
INTRODUCTION AND CONTENT OF REPORT ................................................ 1
1.1 Project participants ......................................................................... 1
1.2 Project .......................................................................................... 1
1.3 Content of this report ...................................................................... 2
2
FIELD WORK .......................................................................................... 2
2.1 Datum, coordinate system and seabed level ....................................... 3
2.2 Seabed CPT ................................................................................... 3
2.2.1 Vessel - Blue Alfa ................................................................... 3
2.2.2 Seabed CPT - Equipment ......................................................... 4
2.2.3 Seabed CPT - Procedures ......................................................... 4
2.2.4 Positioning – Blue Alfa ............................................................. 5
2.2.5 Time log of the CPT campaign .................................................. 6
2.2.6 General comments to seabed CPT testing ................................... 6
2.3 Drilling – Performed from Sound Prospector ....................................... 7
2.3.1 Vessels - Sound Prospector and Sound Provider .......................... 8
2.3.2 Pre-loading of Jack-Up prior to drilling ....................................... 8
2.3.3 Drilling equipment and procedures ............................................ 8
2.3.4 Sampling Procedures and Equipment ......................................... 9
2.3.5 DTH-CPT Equipment ............................................................... 9
2.3.6 DTH-CPT Procedure ...............................................................10
2.3.7 Pressuremeter Testing ...........................................................10
2.3.8 Positioning – Sound Prospector ................................................11
2.3.9 Time log of the BH campaign...................................................12
2.3.10
3
General comments to drilling, sampling and DTH-CPT testing ..12
LABORATORY WORK ..............................................................................12
3.1 Laboratory work in general .............................................................12
3.2 Offshore Laboratory Work ...............................................................12
3.2.1 Geological description ............................................................13
3.2.2 Preservation and storage of samples ........................................13
3.3 Onshore Laboratory Work ...............................................................13
3.3.1 General ................................................................................13
3.3.2 Type of tests.........................................................................14
3.3.3 Advanced Tests overview ........................................................14
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3.4 Borehole logs and photos ................................................................16
4
FACTUAL RESULTS .................................................................................16
4.1 CPT Results ..................................................................................16
4.1.1 Interpreted seabed CPT profiles ...............................................17
4.2 Drilling and Sampling Results ..........................................................17
4.3 Pressuremeter Test Results .............................................................17
4.3.1 General ................................................................................17
4.3.2 Comments to test execution and results ...................................18
4.4 Laboratory Test Results ..................................................................19
4.4.1 Moisture Content ...................................................................19
4.4.2 Bulk and Dry Density .............................................................19
4.4.3 Particle Size Distribution .........................................................19
4.4.4 Liquid and Plastic Limits (Atterberg Limits) ................................19
4.4.5 Particle Density .....................................................................19
4.4.6 Maximum and Minimum Dry Density of Granular Soils ................19
4.4.7 Organic content (Loss on ignition) ............................................20
4.4.8 Chloride Content ...................................................................20
4.4.9 Carbonate Content ................................................................20
4.4.10
Sulphate Content ..............................................................20
4.4.11
Degree of Roundness of Sand .............................................20
4.4.12
Thermal Conductivity ........................................................20
4.4.13
Unconfined Compression Test .............................................20
4.4.14
Saturation Moisture Content ...............................................21
4.4.15
Onedimensional Consolidation Properties of Soil ....................21
4.4.16
Unconsolidated Undrained Triaxial Compression Test (UU) ......21
4.4.17
Consolidated Ansotropically Undrained Triaxial Compression Test
(CAU) ..................................................................................21
4.4.18
Consolidated Drained Triaxial Compression Test (CID) ...........21
4.4.19
Direct Simple Shear Test (DSSst) .......................................21
4.4.20
CAU Triaxial Test Cyclic (CAUcy) .........................................22
4.4.21
C14 Dating Result ..............................................................22
4.5 Comments to laboratory work .........................................................22
5
SOIL CONDITIONS .................................................................................22
5.1 Soil types .....................................................................................23
5.1.1 List of soil types ....................................................................23
5.2 Details on soil types .......................................................................23
5.2.1 Marine Sand .........................................................................23
5.2.2 Glaciolacustrine freshwater deposits .........................................23
5.2.3 Meltwater clay, silt and sand ...................................................24
5.2.4 Upper Till .............................................................................24
5.2.5 Interstadial clay ....................................................................24
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5.2.6 Lower Till .............................................................................25
5.2.7 Limestone ............................................................................25
5.3 Tentative geological history .............................................................25
5.3.1 Cretaceous deposits ...............................................................25
5.3.2 Lower Till .............................................................................26
5.3.3 Meltwater and glaciolacustrine freshwater clay ...........................26
5.3.4 Upper Till .............................................................................26
5.3.5 Lateglacial deposits................................................................26
5.3.6 Postglacial deposits ................................................................27
6
Comparison with the geology from the geophysical investigation ..................27
6.1.1 Post- and Lateglacial deposits..................................................28
6.1.2 Glacial deposits (Upper and Lower Till) .....................................28
6.1.3 Cretaceous Limestone ............................................................28
7
Typical geotechnical characteristics ..........................................................28
8
REFERENCES.........................................................................................32
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Enclosures:
1A.01
General Location Plan
1A.02
Detailed Location Plan
1A.03
Geological Sections
1B.01
Summary - Seabed CPT Tests
1B.02
Summary - DTH CPT Tests
1B.03
Summary - Boreholes
1B.04
Summary - Pressuremeter Tests
1B.05
Summary - Laboratory Test Results
1B.06
Summary - Cone Zero and Offset Report
1B.07
Summary - DPR, Seabed CPT
1B.08
Summary - DPR, Drilling
1C.01
Legend and Definitions, CPT Profiles and Borehole Logs
1D.01
CPT Profiles with qc, fs, u and Rf – Seabed CPT
1D.02
CPT Profiles with qc, fs, u and Rf – Combined Seabed CPT and DTH CPT
1D.03
CPT Profiles with qc, fs, u and Rf – Selected single DTH CPT
1D.04
Interpreted CPT Profiles with qt, ft, Bq,Rft, Qt, Fr, ’, Dr and cu – Seabed CPT
locations without Boreholes
1E.01
Borehole Logs
1F.01
Pressuremeter Logs
1G.01
Selected Photos of Typical Geological Observations
1H.01
Summary – Seabed Levels
1H.02
Jack-Up Leg Penetration
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Appendices:
1A.I
Data Sheet - CPT Vessel, Blue Alfa
1A.II
Data Sheet – GEOscope
1A.III
Positioning Equipment and Positioning Check – Seabed CPT
1A.IV
Cone Calibration Data – Seabed CPT
1B.I
Data Sheet - Jack-Up, Sound Prospector and tug Sound Provider
1B.II
Data Sheet - Drilling and Testing from Jack-Up Platform
1B.III
Data Sheet - Drilling Rig GEOfrigg
1B.IV
Data Sheet – DTH CPT GEOriis
1B.V
Data Sheet - Pressuremeter Equipment
1B.VI
Positioning Equipment and Positioning Check – Drilling
1B.VII
Cone Calibration Data – Drilling
1C.I
Bulk and Dry Density, Moisture and Saturation Moisture Contents
1C.II
Particle Size Distribution
1C.III
Liquid and Plastic Limits (Atterberg Limits) and Particle Density
1C.IV
Maximum and Minimum Dry Density of Granular Soils
1C.V
Degree of Roundness of Sand
1C.VI
Thermal Conductivity
1C.VII
Carbonate, Chloride and Sulphate Content, and LOI (Loss On Ignition)
1C.VIII
Onedimensional Consolidation Properties of Soil
1C.IX
Unconsolidated Undrained Triaxial Compression Test (UU)
1C.X
Consolidated Anisotropically Undrained Triaxial Compression Test (CAU)
1C.XI
Consolidated Drained Triaxial Compressioin Test (CID)
1C.XII
Unconfined Compression Test
1C.XIII
Direct Simple Shear Test (DSSst)
1C.XIV
CAU Triaxial Test Cyclic (CAUcy)
1C.XV
C14 Dating Result
1D.I
GEO Guideline – Pressuremeter Test
1D.II
GL01, Angularity test
1D.III
Deltares procedure – 300-W-T1-FB-03
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1 INTRODUCTION AND CONTENT OF REPORT
1.1 Project participants
The Danish Transmission System Operator, Energinet.dk , has been instructed by the
Danish Energy Agency (Energistyrelsen) to develop the Offshore Wind Farm Kriegers
Flak. Energinet.dk has contracted SSE AB to conduct a preliminary geotechnical site investigation at the planned Kriegers Flak Offshore Wind Farm (OWF). SSE AB has subcontracted GEO to perform the Technical Investigation.
1.2 Project
The overall objective of the present preliminary geotechnical investigation of the Kriegers
Flak area is to collect geological and geotechnical information for a later evaluation of the
foundation and installation conditions for the Offshore Wind Farm.
The Kriegers Flak Offshore Wind Farm is planned as a 600 MW offshore wind farm.
Kriegers Flak is a shallow area of approximately 150 km2 in the Southern Baltic Sea 15
km east of the Danish coast. Kriegers Flak is cut by the exclusive economic zone (EEZ)
offshore borders of Sweden, Denmark and Germany with the Danish section being the
largest part. A sub-area in the middle of the Kriegers Flak area is reserved for sand abstraction and is excluded from the investigation.
The OWF pre-investigation area encompasses the Danish part of the Kriegers Flak bank.
Water depths across the Kriegers Flak pre-investigation area vary approximately between 15 m to 30 m.
The approximately location of Kriegers Flak Offshore Wind Farm is shown in Figure 1.1.
Details of the investigated locations are included in Enclosures 1A.01 and 1A.02.
The investigation includes Cone Penetration Testing (CPTs) to a target depth of 50 m
below seabed and geotechnical boreholes including down the hole CPTs (DTH-CPT) with a
target depth of 50 or 70 m below seabed.
The CPT campaign was carried out with GEO’s in-house 20 t seabed rig GEOscope. A
total of 67 deep push seabed CPTs were performed at 42 locations within the Kriegers
Flak OWF site. The total number of CPTs exceeds the number of locations due to performance of re-runs. The penetration of the seabed CPTs reached between 0.6 and 26.7 m
below seabed with an average penetration of 13.7 m.
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Figure 1.1 The approximately location of Kriegers Flak Offshore Wind Farm
The geotechnical borehole campaign was carried out from the Jack-Up Sound Prospector
using GEO’s land based drilling rig and DTH-CPT equipment. A total of 17 geotechnical
boreholes were performed at 17 locations within the Kriegers Flak OWF site. 6 of the
boreholes were drilled to the target depth 70 m below seabed and 11 of the boreholes
were drilled to the target depth 50 m below seabed.
1.3 Content of this report
This Report includes all main factual results from the CPT and the borehole campaigns:

Details of the Field Work

Details of the Laboratory Work

CPT results (Seabed CPTs and DTH-CPTs)

Interpretation of the seabed CPT data for the locations where no borehole was performed

Classification test results from the boreholes campaign

Advanced laboratory test results from the boreholes campaign

Description of the Soil Conditions met at the Kriegers Flak OWF site.
2 FIELD WORK
The Geotechnical Operation was performed in two groups of operations:

Seabed CPT – Performed with the 20 t seabed rig GEOscope from the vessel Blue Alfa

Drilling – Performed from the Jack-Up Sound Prospector assisted by the tug Sound
Provider
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2.1 Datum, coordinate system and seabed level
All work are carried out referring to datum WGS84. Coordinates (x,y) are provided according to UTM Zone 32N.
The vertical reference (z) is relative to DVR90 m converted using the geoid model
DKGEOID02.
All CPT and borehole data is registered with reference to the level of the seabed. To
avoid any inconsistency between various measurements of the seabed level, it was decided to reference all depths relative to the seabed levels provided by the Client, /2/,
based on bathymetric data from the geophysical survey 2012.
Seabed level measurements were performed both during the CPT and the borehole campaign. A comparison of the bathymetric levels with the measured levels is presented in
Enclosure 1H.01.
2.2 Seabed CPT
The CPT campaign was carried out in May 2013 using the seabed rig GEOscope operated
from the DP1 vessel Blue Alfa. The operations were conducted on a continual 24-hour
basis.
A total of 67 deep push seabed CPTs were performed at 42 locations. The total number
of CPTs exceeds the number of locations due to performance of additional tests (reruns). At locations, where the CPT penetration was considered insufficient by the Client,
a re-run was performed. In general a re-run was performed if the first CPT at a location
did not reach 8 m below seabed.
The penetration of the seabed CPTs varied between 0.6 and 26.7 m below seabed with
an average penetration of 13.7 m.
All test locations are shown on the general location map, Enclosure 1A.01 and the detailed location plan, Enclosure 1A.02.
A summary of the investigated locations are detailed in Enclosure 1B.01.
The results from the CPT campaign are presented in detail in section 4.1.
2.2.1
Vessel - Blue Alfa
The CPT campaign at Kriegers Flak OWF was performed from the DP I vessel Blue Alfa
supplied by the subcontractor Blue Star Line A/S.
The vessel Blue Alfa has an overall length of 65.6 m and maximum draft of 6.0 m. It is
equipped with in total 6620 kW engine and two thrusters on 600 hp.
The vessel is depicted on Figure 2.1 and further data can be found in Appendix 1A.I.
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Figure 2.1 – The vessel Blue Alfa
2.2.2
Seabed CPT - Equipment
Seabed CPTs was performed with GEOs in-house 20 t seabed CPT-rig GEOscope. The
overall dimensions of the GEOscope system are; base plate diameter 2.4 m, height 3.4
m and total a weight of 27.6 ton providing 200 kN thrust at seabed. The rig was handled
by GEOs modular launch/recovery system installed over the moon pool of the vessel.
A general description and technical specifications for the GEOscope set-up are presented
in Appendix 1A.II and the setup is depicted on Figure 2.2.
Figure 2.2 – GEOscope installed over the moon pool on Blue Alfa
2.2.3
Seabed CPT - Procedures
The seabed CPT’s were conducted in accordance with the ISSMGE International Reference Test Procedure for CPT (IRTP 2001). Tip resistance, sleeve friction, pore water
pressure and inclination of the cone were recorded during each test. The CPT cones used
were of the standard Van den Berg 60-degree type with cross sectional areas of 10 cm².
All CPT cones were calibrated in accordance with the Contract Specification and GEO procedures. Detailed information related to CPT cone calibration is included in Appendix
1A.IV. The CPT cone geometry, filter and sleeve diameter, joint-widths and rods are in
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agreement with the IRTP recommendations. On all tests a friction reducer has been applied.
The basic CPT thrust system is a hydraulic dual clamp system, applying continuous penetration and full control of the total thrust applied to the CPT rods. The cone penetration
velocity was 20 mm/sec. The test data (qc, fs and u) and tool inclination were recorded
approximately every second.
The tests were generally terminated in accordance with one of the following criteria:

Max required penetration depth

Total penetration resistance of 200 kN

Sleeve friction of 2.4 MPa

Tip resistance of 100 MPa

Gradual increase of cone inclination to max. 15 deg.

Sudden increase of inclination more than 3 deg.

Operator stop if evaluated that further testing can damage the equipment
System checks:
Each cone was checked and approved to be fully functional in the field prior to
deployment using a special field-press system, which checks the output signals from the
cone tip, sleeve stress and pore pressure. The pore pressure filter stones were all
saturated in glycerine or water prior to deployment.
The offset of each cone sensor was eliminated (zeroed) after the rig had settled on the
seabed just before commencement of the test, at which time the cone tip was positioned
at the reference level (0.72 m above seabed). To check the full functionality of the cone
after the test the zero values were recorded again and compared with the initial ones. A
list of these values and deviations are found in Enclosure 1B.06.
2.2.4
Positioning – Blue Alfa
2.2.4.1 Positioning Procedure – Blue Alfa
During positioning of Blue Alfa and GEOscope a navigation display showing the target
location (waypoint) and the actual position of GEOscope was provided to the captain/officer to enable him to navigate the vessel to the desired location.
For each target location the actual position was recorded when the vessel was in position
and the CPT equipment (GEOscope) was landed on the seafloor and just before the work
was commenced. Navipac, the utilised positioning software, collected positioning data for
approximately 1 min and calculated the average position. This position was recorded and
reported in the Final Positioning Report.
2.2.4.2 Positioning Equipment – Blue Alfa
Two independent DGPS systems have provided the surface positioning during the project.
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The primary and the secondary positioning system used on this project, have both been
Veripos LD2 Ultra Service, which offers decimetre level position accuracy globally. Technical details for the equipment are enclosed in Appendix 1A.III.
The navigation computation was executed with NaviPac software.
2.2.4.3 Verification of positioning system – Blue Alfa
To verify the accuracy of the positioning systems on board the Blue Alfa a position check
was performed at a known location (in Fåborg port). A calibration of the equipment was
also performed. Both the gyro calibration measurements and the measurements of offsets to verify the accuracy were performed by assistance of the external survey company
Hvenegaard & Jens Bo from Odense.
Documentation for the positioning check is included in Appendix 1A.III.
2.2.4.4 Positioning data and seabed level – CPT locations
The positions of the CPT locations are presented on the CPT logs Enclosure 1D.01 and on
the Borehole Logs Enclosure 1E.01. A summary of the investigated CPT locations including coordinates is also detailed in Enclosure 1B.01.
The seabed level at the CPT locations were determined prior to each CPT test based on
the data from bathymetric survey. The monitoring of the data observed during the CPT
investigation included:

Measurement of the water depth by the use of pressure transducer on GEOscope

Determining the elevation by the primary positioning system Veripos Ultra

Calculating the seabed level based on the above two measurements
The bathymetric levels and the measured levels are presented in Enclosure 1H.01.
2.2.5
Time log of the CPT campaign
A summary of Daily Progress Reports is given in Enclosure 1B.07.
2.2.6
General comments to seabed CPT testing
The majority of the tests were carried out as planned. Specific comments to the individual tests are included on the CPT Summary, Enclosure 1B.01.
General comments to the tests are:

In some tests, where a stop criterion was reached close to seabed, the test was
continued by a “stop and go” if a low risk for cone damage was estimated by the
operator. In this case (“stop and go”) the cone is withdrawn approx. 0.5 m before
the penetration was continued. Generally, this procedure enabled further penetration depth with small extra time consumption

In some of the tests, the pore pressure measurements do not correspond to the
hydrostatic pressure just after the test (see Enclosure 1B.06). This may have
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been caused by cavitation inside the filter stone causing a subsequent “blocking”
of the filter and erroneous measurements “sluggish response” (e.g. KF-CP001,
KF-CPT003a and KF-CPT005). This phenomenon is described by Lunne, T., 1997,
ref./3/

At position KF-CPT001, KF-CPT003 and KF-CPT025 the CPT rods broke during
testing. Rods and cones were abandoned in the ground at these positions. Rods
were also dropped at the seabed at KF-CPT001.

Due to a human error during positioning the test at KF-CPT001 was performed
approximately 15 m away from the originally intended position. The test position
was later accepted by the offshore Clients Representative.
2.3 Drilling – Performed from Sound Prospector
The geotechnical borehole campaign was carried out from the Jack-Up Sound Prospector
in the period May to June 2013. The drilling was carried out with GEO’s land based drilling rig and GEO’s in-house down the hole CPT (DTH-CPT) equipment. The platform was
assisted by the tug boat Sound Provider. All operations were conducted on a continual
24-hour basis.
The geotechnical borehole campaign included 17 sampling boreholes, 11 with a target
depth of 50 meters below seabed and 6 with a target depth of 70 meters below seabed.
In all boreholes DTH-CPTs have been performed below the refusal depth for the corresponding seabed CPT. At the 17 borehole locations a total number of 250 DTH-CPTs were
performed. The penetration of the DTH-CPTs reached between 0.03 and 1.8 m with an
average penetration of 0.9 m. Additional, a total of 10 pressuremeter tests in 4 of the
boreholes were performed.
The boreholes were carried out as a combination of rotary-, percussion- and core drilling.
The boreholes have been performed as combined boreholes including both sampling and
DTH-CPTs. Sampling and DTH-CPT testing were performed in 1.5 m intervals.
All samples from the boreholes have been logged and photographed offshore. Classification-, chemical-, strength- and deformation tests have been executed on selected samples. Testing has been performed either offshore or onshore depending on test type.
Details of the laboratory work can be found in Section 3.
All borehole (BH) locations are shown on the general location map, Enclosure 1A.01 and
on the detailed location plan, Enclosure 1A.02.
A summary of the investigated BH locations are detailed in, Enclosure 1B.03.
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2.3.1
Vessels - Sound Prospector and Sound Provider
The Jack-Up platform Sound Prospector was used during the borehole campaign. The
platform was assisted by the tugboat Sound Provider. Both the platform and the tug
were supplied by SSE AB.
Sound Prospector, was built in 2007, has a deck area of 20 x 30 m and is equipped with
50 m legs. The Sound Prospector was for the present job equipped with circular spudcans with a diameter of 3 m. The Jack-Up is depicted on Figure 2.3.
Technical specifications for Sound Prospector and Sound Provider are given in Appendix
1B.I.
Figure 2.3. Sound Prospector jacked up
2.3.2
Pre-loading of Jack-Up prior to drilling
On all positions a pre-loading of the Jack-Up was performed. The platform was first
jacked-up on all four legs. Then two legs on a diagonal were retracted so the total weight
of the platform (approx. 740 ton) rested on 2 legs. This was repeated with the opposite
set of legs. With this procedure the preloading is done with up to approx. 370 ton on
each leg. After a stable position was achieved the platform climbed up to safe height with
a minimum air gap of 1.2 m above the high tide/max wave height.
2.3.3
Drilling equipment and procedures
The drilling work was carried out using one of GEOs land based hydraulic drilling rigs.
The rig used was a Nordmeyer full hydraulic DSB 1/5 drilling rig (“GEOfrigg”). Drilling
was performed through a 400 mm moon pool located approx. 5 m from the centre of the
platform.
The technical specification for the Nordmeyer DSB 1/5 drilling rig is presented in the
datasheet included as Appendix 1B.III.
The following drilling methods have been used:

Cased dry rotary drilling

Percussion drilling
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
Core drilling
In the topmost formations below seabed, drilling was performed as cased rotary drilling
or percussion drilling. For both drilling methods 8” casings were used.
Appendix 1B.II and 1B.III provides the technical specifications of GEO’s drill spread mobilised on Sound Prospector.
Subject to the nature of the geology, core drilling was commenced at different depths.
The core drilling was performed using the Geobor-S triple tube core system. Commencement of the core drilling was agreed between the Clients Representative and the
GEO Site Manager.
The applied drilling methods for the individual sections of the boreholes are marked on
the borehole logs, Enclosure 1E.01.
2.3.4
Sampling Procedures and Equipment
2.3.4.1 Undisturbed sampling, Shelby tubes
Undisturbed samples have been collected typically at 1.5 meter intervals or as directed
by the Client in cohesive soil during the rotary- or percussion drilling. Undisturbed samples have been collected in sampling tubes (Shelby) as push samples. The sampling
tubes have an OD = 75 mm and ID = 70 mm. The length of the tubes was either 0.7 m
or 1 m.
2.3.4.2 Disturbed sampling, Hammer samples
Hammer samples have been collected typically at 1.5 meter intervals or as directed by
the Client in non-cohesive soil during the rotary- or percussion drilling. Samples have
been collected in PVC liners with an OD = 80 mm and ID = 75 mm. The length of the
liners was 1 m.
2.3.4.3 Disturbed sampling, bag samples
Disturbed samples have been collected over the borehole sections, where no undisturbed
samples or cores were extracted. The majority of the disturbed samples have been collected as bag samples from the drilling tools (bailer/closed auger).
2.3.4.4 Cores
All cores have been collected in the PVC liners, which forms part of the Geobor-S core
drilling system with OD = 146 mm and ID = 102 mm. The core runs length ranged between 0.5 m and 1.5 m depending on the geological conditions.
2.3.5
DTH-CPT Equipment
In all boreholes the DTH-CPTs have been performed with GEOs in house DTH-CPT
equipment GEOriis. With GEOriis it is possible to lock or latch the tool in the 8” casing or
in the Geobor-S drill string. With the listed equipment it is possible to perform a CPT test
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with a stroke of maximum 2 m below bottom of the borehole. The maximum thrust capacity for the equipment is 120 kN.
A detailed description of the equipment is presented in Appendix 1B.IV.
2.3.6
DTH-CPT Procedure
The DTH-CPT’s were conducted with 10 cm2 Van den Berg cones in accordance with the
ISSMGE International Reference Test Procedure for CPT (IRTP 2001). No friction reducers
have been used. All CPT cones were calibrated in accordance with the Contract Specification and GEO procedures. Detailed information related to CPT cone calibration data is
included in Appendix 1B.VII.
The tests were generally terminated in accordance with one of the following criteria:

Max required penetration depth (typically 1.5 m)

Total penetration resistance of 120 kN

Sleeve friction of 2.4 MPa

Tip resistance of 100 MPa

Gradual increase of cone inclination to max. 15 deg.

Sudden increase of inclination more than 3 deg.

Operator stop if evaluated that further testing can damage the equipment.
System checks:
Each cone was checked and approved to be fully functional in the field prior to
deployment using a special field-press system, which checks the output signals from the
cone tip, sleeve stress and pore pressure. The pore pressure filter stones were all
saturated in glycerine or water prior to deployment.
Prior to commencement of any DTH-CPT testing, offsets of each cone sensor was eliminated (zeroed) after the tool had been placed at the bottom of the borehole, at the test
start level. To check the full functionality of the cone upon testing, the zero values were
recorded again at the same level after completed test and compared with the initial ones.
All system checks are performed in accordance with ISO 119901-8
2.3.7
Pressuremeter Testing
The tests were performed in accordance with ASTM D 4719-7 standard “Standard Test
Methods for Prebored Pressuremeter Testing in Soils”. The standard is further detailed
and made operational in GEOs Guideline “Pressuremeter Testing” which can be found in
Appendix 1D.I.
The equipment used was a TEXAM pressuremeter which is further described in Enclosure
1B.V.
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2.3.8
Positioning – Sound Prospector
2.3.8.1 Positioning Procedure – Sound Prospector
For the BH campaign GEO utilised a GPS RTK system in order to get the best possible
correction data. This system worked with a reference station placed at the Fino weather
mast located in the German part of Kriegers Flak.
During positioning of Sound Prospector a navigation display showing the target BH location (waypoint) and the actual position of Sound Prospector and Sound Provider was provided to the captain/officer to enable him to navigate the Jack-Up to the selected location.
For each target location the actual position of the moon pool ( borehole location) and of
each leg) were recorded (in x,y,z) when the Jack-Up was in position. The final position
was logged after the preloading procedure and before the work was commenced. Navipac, the utilised positioning software collected positioning data for approximately 1 min
and calculated the average position for the moon pool and each leg. Additionally the
penetration of each leg was calculated. The positions and leg penetrations were recorded
and documented on the Final Positioning Report. The positions reported for the investigated BH locations are based on the Final Positioning Reports.
A summary of leg positions and penetration depths/levels for each borehole position is
presented in Enclosure 1H.02.
2.3.8.2 Positioning Equipment – Sound Prospector
Two independent DGPS systems have been used for the positioning of the platform. An
Ashtech Proflex 500 GNSS GPS with RTK correction signals was used as the primary positioning system. The secondary positioning system used was an Ashtech GPS Z12 DGPS
(IALA) receiver. A description of the two positioning systems used is given in Appendix
1B.VI.
2.3.8.3 Verification of positioning systems
A gyro calibration was performed in Malmö during the mobilisation to align the gyro.Further the key points on the platform (e.g. moon pool, legs) were measured and all
data were entered into the positioning system as offsets referring to the main antenna.
Both the gyro calibration measurements and the measurements of offsets were controlled by the external survey company Hvenegaard & Jens Bo from Odense.
The position check prior to the geotechnical borehole campaign was performed at the
first borehole location by the external company Nellemann Survey A/S. Documentation
of the positioning check is given in Appendix 1B.VI.
2.3.8.4 Positioning data
The test positions coordinates (x,y) are given on the borehole logs, Enclosures 1.E.01.
Positions are also included in the summaries on Enclosures 1B.01 and 1B.03.
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The seabed level for the individual borehole locations has been determined during the
initial part of the drilling operation. The monitoring included:

Measurement, by the use of a plumb, the distance from deck to seabed level. The
measurement was performed inside the drill casing when drill casing was installed
at seabed

Determining the deck elevation by the primary positioning system RTK

Calculating the seabed levels based on the above two measurements
The bathymetric levels and the measured levels are presented in Enclosure 1H.01.
2.3.9
Time log of the BH campaign
A summary of Daily Progress Reports is given in Enclosure 1B.08.
2.3.10 General comments to drilling, sampling and DTH-CPT testing
The marine operation, drilling work, sampling and testing were in general carried out as
planned. At borehole KF-BH010 a piece of casing was lost in the borehole 15.5 m below
seabed.
3 LABORATORY WORK
3.1 Laboratory work in general
Both offshore and onshore laboratory work have been executed.
Subsampling for onshore testing was performed offshore. Onshore testing has been performed at the onshore laboratories:
GEO – Maglebjergvej 1, 2800 Kgs. Lyngby, DK-Denmark
GEOLABS – Bucknalls Lane, Garston, Watford, Hertfordshire, WD25 9XX, UK
Deltares - Stieltjesweg 2, 2628 CK Delft, 2600 MH Delft, NL-Netherlands
Types of tests performed onshore are detailed in section 3.3.
Based on the sample material retrieved from the borehole the geologist suggested a laboratory program for offshore and onshore testing. The final program was approved by
the Client.
3.2 Offshore Laboratory Work
The following tasks have been carried out in the offshore laboratory:

Extruding Shelby tubes and splitting PVC liners (hammer and core samples)

Core logging, geological description by a geologist of all samples

Photography of all shelby tubes, core samples and hammer samples,

Pocket penetrometer on appropriate cohesive soil samples
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
Determination of moisture content

Determination of bulk density

Determination of Total Core Recovery (TCR) for all cores

Determination of Rock Quality Designation (RQD) for all limestone cores

Selection and preservation of disturbed and undisturbed subsamples for onshore
testing

Determination of induration (H) and fissuring (S) on undisturbed limestone cores.
For the cores drilled out after the DTH-CPTs the induration and fissuring has not
been determined since the CPT cone/rods effects the mentioned determinations.
3.2.1
Geological description
Samples and cores have been reviewed in the offshore laboratory by a certified geologist. The geological description has been performed based on Danish Geotechnical Society Bulletin No. 1E /1/.
3.2.2
Preservation and storage of samples
The samples have been preserved as follows:



Shelby tubes – Preservation of the extruded sample is done in polythene film, aluminium foil, wax and cardboard tubes, alternatively in a plastic bag
Core samples – Preservation of sub-samples is done in polythene film, aluminium
foil, wax and cardboard tubes.
Bulk samples – Each sample and subsample is stored in a plastic bag, which
again is stored in a heavy duty plastic bag for each borehole.
All sub-samples were stored in solid plastic containers.
The remaining part of core samples, not selected as laboratory test specimens, was carefully sealed and stored in GEOs standard core storage rack. In the rack, the cores have
been packed into their PVC liners and plastic and stored in layflat to prevent moisture
loss or damage during subsequent transportation. In the sections where sub-samples
have been collected, rigid core spacers (foam pieces) is inserted representing the lengths
of the missing core sections. The parts of the disturbed samples, not selected for testing,
will also be stored in the rack system.
Stored samples and sub-samples and their handling are protected from shock, frost and
excessive heat.
3.3 Onshore Laboratory Work
3.3.1
General
A suggested laboratory program was prepared for each borehole by the offshore geologist and the required tests were ordered by the Client. The laboratory program accompanied the samples to the onshore laboratories for testing.
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3.3.2
Type of tests
An overview of the laboratories used for testing and the type of tests performed are
shown in Tabel 3.1.
GEO
Moisture Content
Bulk and Dry Density
GEOLABS Deltares
Standard
X*)
X
CEN ISO/TS 17892-1
*)
X
CEN ISO/TS 17892-2
Particle Size Distribution
X
X
CEN ISO/TS 17892-4
Liquid and Plastic Limit
X
CEN ISO/TS 17892-12
Particle Density
Maximum and minimum Dry Density of Granular
soils
Organic content
X
CEN ISO/TS 17892-3
x
BS 1377-4: 1990
X
ASTM D2974
Chloride content
X
BS 1377-3:1990
Carbonate Content
X
BS 1377-3:1990
Sulphate content
X
Degree of Roundness of Sand
x
Thermal Conductivity
X
BS 1377-3:1990
GL01, Angularity test
(GEO)
ASTM D5334-08
Unconfined Compression test on fine grained soil
X
Saturation Moisture Content
X
Onedimensional Consolidation properties of soil
X
CEN ISO/TS 17892-5
Unconsolidated Undrained Triaxial Compression
X
CEN ISO/TS 17892-8
X
CEN ISO/TS 17892-9
X
CEN ISO/TS 17892-9
Consolidated Ansotropically Undrained triaxial
compression test
Consolidated Drained Triaxial Compression Test
Direct Simple Shear Test
CEN ISO/TS 17892-7
BS1377-2
Clause 3.3: 1990
X
CAU Triaxial Test Cyclic
X
BS1377-5:1990 and
ASTM D6528 – 07
Deltares procedure
300-W-T1-FB-03
Table 3.1. Laboratories and Standards used for onshore testing.
Note
*)
3.3.3
Tests also performed offshore
Advanced Tests overview
The distribution of advanced tests performed on selected samples from the boreholes is
summarized in Table 3.2.
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Borehole Information
Borehole
Main Soil
ID
Type
KF-BH001
Clay
Limestone
Sand
Clay
Clay Till
Limestone
Clay
Clay Till
Limestone
Sand
Clay
Clay Till
Limestone
Clay
Clay Till
Limestone
Clay
Clay Till
Sand
Clay
Limestone
Clay
Clay Till
Limestone
Silt
Clay
Clay Till
Limestone
Clay
Clay Till
Limestone
Clay
Clay Till
Limestone
Silt
Clay
Limestone
Clay
Clay Till
Limestone
Clay
Limestone
Clay
Clay Till
Limestone
Clay
Limestone
Clay
Limestone
KF-BH002
KF-BH003
KF-BH004
KF-BH005
KF-BH006
KF-BH007
KF-BH008
KF-BH009
KF-BH010
KF-BH011
KF-BH012
KF-BH013
KF-BH014
KF-BH015
KF-BH016
KF-BH017
Number of Performed Advanced Tests
Oedometer Test
IL 1
IL 2
UU
CAU
CID
DSSst
CAUcy
UCS
LongT
1
2
1
2
1
1
3
1
1
2
1
2
1
3
1
3
1
2
2
1
2
1
1
3
1
1
1
3
1
3
1
2
1
1
1
1
3
1
2
1
2
2
2
1
1
3
1
1
3
1
2
2
3
1
2
1
2
1
1
3
1
2
1
4
2
2
1
1
3
4
2
3
1
2
1
4
2
1
2
1
1
3
1
1
4
1
1
1
1
2
2
3
Table 3.2. Summary of performed advanced tests.
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Test specifications for CAU, CID and DSSst have been prepared by GEO based on general
knowledge of the soils tested and in accordance with the reference standards.
Two types of consolidation tests have been performed. The first test was performed to
determine the pre-consolidation pressure, and is referred to as IL 1. The second test
included loops of loading, unloading and loading. Three “loading loops” were originally
planned, but not performed due to the limited difference in stress between the in-situ
stress and preconsolidation stress. These tests are referred to as IL 2. On five selected
tests the creep was continued beyond end of primary consolidation (typically 24 hours)
for determination of the coefficient of secondary compression. These tests are indicated
with a “LongT” in Table 3.2.
Where possible, the consolidation pressure for the CAU, CID and DSSst tests have been
determined from the IL 1 test. If results were not available, the in-situ stress estimated
from the depth were used as consolidation pressure.
The relative density used for the CID tests on sand were estimated from the CPT tests
The CAU cyclic tests have been preconsolidated to a stress level similar to the static
tests. Testing comprised up to 1500 cycles at 0.1 Hz. The detailed testing procedure is
described in the Deltares procedure 300-W-T1-FB-03 included in Appendix 1D.III.
3.4 Borehole logs and photos
Key results from the fieldwork and laboratory work are described in Section 4, and presented on the borehole logs, Enclosure 1E.01. References to detailed results are marked
on the right hand side of the borehole logs.
Legend and definitions for the borehole logs are presented in Enclosure 1C.01.
Colour photos have been taken of all shelby tubes, cores and hammer samples, The photos include the sample identification, a scale in centimetre, depth below seabed and a
scale colour card. The colour photos are also forwarded in digital format.
A selection of typical samples for the Kriegers Flak site including geological descriptions
are listed in Enclosure 1G.01.
An overview of the geological conditions at the Kriegers Flak site is described further in
Section 5.
4 FACTUAL RESULTS
4.1 CPT Results
The seabed CPTs are presented on a CPT profile for each test. All tests are presented
with the standard depth scale of 1 cm = 0.5 m. The plots show the measured values qc,
fs, u and Rf for each seabed CPT test, and are included in Enclosures 1D.01.
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For each of the 17 locations where DTH-CPTs were performed in the boreholes additional
to the seabed CPT the CPT tests are presented in combination. A combined CPT profile
for each location is included in Enclosures 1D.02.
For 5 of the locations the DTH-CPT closest to the top of the borehole is overlapped by the
seabed CPT. These single DTH-CPTs are presented on a CPT profile for each test location
in Enclosure 1D.03.
Summaries of the seabed CPTs and the DTH CPTs including the final penetration depths,
coordinates, water depths and stop reasons for each CPT test can be found in Enclosure
1B.01 and Enclosure 1B.02, respectively.
Legend and definitions for the profiles are presented in Enclosure 1C.01.
4.1.1
Interpreted seabed CPT profiles
The interpretation of the CPT data have been based on empirical methods. The interpretation covers strength parameters and soil type behaviour determination. The test results are presented on a CPT plot for each test. The interpretation methods and results
are included in Enclosure 1D.04
4.2 Drilling and Sampling Results
An overview of the 17 boreholes including the final borehole depths, location coordinates
and water depths are listed in a Borehole summary sheet included as Enclosure 1B.03.
The results for each borehole are presented on a Borehole log for. The individual logs can
be found in Enclosures 1E.01.
4.3 Pressuremeter Test Results
4.3.1
General
Pressuremeter tests were performed, at selected locations and depths as instructed by
the Client. A total of 10 tests were carried out in four appointed boreholes with 4 tests in
KF-BH002, 1 test in KF-BH005, 3 tests in KF-BH010 and 2 tests in KF-BH016.
A summary of the performed tests, general soil characteristics and derived pressuremeter results (Pressuremeter Modulus and Limit Pressure) are given in Enclosure 1B.04.
The test itself is presented in Enclosure 1F.01.
The upper part of each log in Enclosure 1F.01 shows the pressuremeter curve with indication of the single reading. The curve has been both pressure and volume corrected
according to normal practice (the procedure is described in ASTM D4719-07). It should
be mentioned that the pressure is shown as Corrected Pressure applied to the probe. The
outer water pressure has thus not been subtracted. The pressure from the water column
in the casing can be calculated by the water level in the casing and the probe level –
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both indicated in the enclosures (however this pressure is not necessarily present on the
entire probe wall during inflation).
The pressuremeter modulus (EP) is calculated from the straight line medium section of
the pressuremeter curve. However, for some of the tests this section of the curve has
only partly been measured as mentioned in section 4.3.2. The slope of the curve has
been evaluated based on the most suitable measured section and the pressuremeter
modulus calculated and shown in the enclosure.
The limit pressure has been determined according to the definition as the pressure corresponding to an expansion as twice the volume of the probe (cross section area multiplied
with the length). As the tests cannot be made to this expansion (as the probe may burst)
the pressuremeter curve is extrapolated and the pressure corresponding to this volume
determined and shown in the enclosures. The extrapolation has been made by the assumption that a straight line is obtained for the last section of the pressuremeter curve
in a pressure versus the reciprocal volume plot. This procedure is usually used and indicated in ASTM D4719-07.
4.3.2
Comments to test execution and results
Precaution was made to perform the test as adequate as possible, however, some limitations have affected the tests:

Pres_BH002-1, Pres_BH002-3, Pres_BH010-3 and Pres_BH016-1:
Even with the most careful and slow retrieval of the sampler it could not be
avoided that the diameter of the test cavity was too small compared to the optimal size for an optimal test. The reason for this is believed to be soft possibly
non-homogeneous clay might have altered the surface of the intended cylindrical
test cavity. That the hole was to small became evident as the probe could only be
installed by means of a small pressure. This means that a certain soil pressure is
observed on the probe even though no inflation has been applied. Although the
conditions of the soil near the probe might have disturbed significantly a simple
assumption can be made during the interpretation: the entire diameter of the
cavity was generally decreased. This means that the first section of the pressuremeter curve was not determined but the last section was correctly measured.
As this assumption is extremely rigid, these test results shoul be treated as indicative values only.

Pres_BH002-4, Pres_BH016-1:
The recovery of the sample tube was less than the required length for the test
cavity. In agreement with the Client’s representative onboard, the test was attempted with the probe pushed down as far as possible. Both tests are affected in
the last part of the curve, used for the limit pressure. This behaviour is believed
to originate from a soil failure developing in the top of the test cavity, at pressures exceeding the pseudo elastic area.

Pres_BH002-3 and Pres_BH016-2:
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The pressuremeter curve shows unusual behaviour. These are caused by nonhomogeneous soil at the probe level. This is verified by a study of the BH logs.
4.4 Laboratory Test Results
The individual laboratory tests and results are described further below.
An overall summary of test results from the different laboratory test are included in Enclosure 1B.05. The laboratory results are also included on the borehole logs in Enclosure
1E.01. Reference to detailed information for the different test types are given in the sections below
On a number of the test sheets a soil description is included. This description is the laboratory technician’s visual description, therefore, not always in line with the final geological description included on the borehole logs.
4.4.1
Moisture Content
Moisture content determination was made offshore on samples with approx. 1.5 m intervals in cohesive and limestone formations. Moisture content is also determined in connection with different laboratory tests e.g. Liquid and Plastic limits.
The results of the moisture content determinations are included in Appendix 1C.I.
4.4.2
Bulk and Dry Density
Bulk and dry density determinations were made offshore on selected undisturbed samples and onshore.The bulk- and dry densities determined onshore for limestone formations are also included in Appendix 1C.I.
4.4.3
Particle Size Distribution
Particle size distribution analyses were undertaken on sub-samples by sieving only or as
a combination of sieving and hydrometer tests.
The detailed results from tests are presented on the Particle Size Distribution Curves
enclosed as Appendix 1C.II.
4.4.4
Liquid and Plastic Limits (Atterberg Limits)
Liquid and plastic limits determinations (Atterberg limit) were carried out on selected
sub-samples. The results are presented in Appendix 1C.III
4.4.5
Particle Density
Particle density determination was made on selected sub-samples. The results of the
determinations are given in Appendix 1C.III.
4.4.6
Maximum and Minimum Dry Density of Granular Soils
Maximum and minimum Dry Density of Granular soils determination was carried out on
selected sub-samples. The results are included in Appendix 1C.IV
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4.4.7
Organic content (Loss on ignition)
Determination of the organic content of soil was performed for selected sub-samples by
loss on ignition testing. The results are presented in Appendix 1C.
4.4.8
Chloride Content
Determination of the chloride content of soil was done for selected sub-samples utilising
a method for estimation of Total Chloride. The results of the chloride content determinations are presented in Appendix 1C.VII.
4.4.9
Carbonate Content
Determination of the carbonate (as CaCO3) content was done for selected sub-samples of
soil. The results of the carbonate content determinations are presented in Appendix
1C.VII.
4.4.10 Sulphate Content
Determination of the sulphate content of soil was done for selected sub-samples utilising
a method for determination of water soluble sulphate. The results of the sulphate content determinations are presented in Appendix 1C.VII.
4.4.11 Degree of Roundness of Sand
Determination of roundness of sand (grain angularity) was determined at selected samples.
Prior to the roundness determination a sieve analysis was performed in order to determine the grading (number of subsamples) to be included in the roundness determination.
The test has been performed in accordance with GEO´s procedure for Angularity Test
included in Appendix 1D.II
The results of the roundness determinations are presented in Appendix 1C.V.
4.4.12 Thermal Conductivity
Determination of the thermal conductivity (reciprocal of thermal resistivity) of soil has
been undertaken on a number of selected sub-samples. All tested samples were located
within the first 3 metres below seabed. The results of the tests are presented in Appendix 1C.VI.
4.4.13 Unconfined Compression Test
Determinations of the Unconfined Compression Strength (UCS) were undertaken on a
number of limestone sub-samples. The detailed results of the UCS tests are enclosed in
Appendix 1C.XII.
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4.4.14 Saturation Moisture Content
Saturation moisture content was determined on a number of the limestone sub-samples.
The results are given in Appendix 1C.I.
4.4.15 Onedimensional Consolidation Properties of Soil
Onedimensional Consolidation properties of soil were determined for selected specimens
of undisturbed cohesive soil. It was determined by Oedometer tests with Incremental
Loading (IL).
The results including both type 1 and type 2 tests and time curves for 5 samples (detailed described in section 3.3.3) are presented in Appendix 1C.VIII. The calculated preconsolidation pressure and oedometer modulus are included in the Summary - Laboratory Tests, Enclosure 1B.05.
The preconsolidation pressure has been calculated using the Casagrande method described in CEN ISO/TS 17892-5.
4.4.16 Unconsolidated Undrained Triaxial Compression Test (UU)
A determination of the undrained shear strength in triaxial compression without measurement of pore pressure was undertaken on a number of undisturbed cohesive subsamples. Results of the tests are presented in Appendix 1C.IX. The shear stresses calculated from the UU-tests are given in the Summary – Laboratory Test Results, Enclosure
1B.05.
4.4.17 Consolidated Ansotropically Undrained Triaxial Compression Test (CAU)
The Consolidated Undrained (CU) triaxial compression tests were performed anisotropically as CAU tests. The results of the CAU triaxial tests are presented in Appendix 1C.X.
The undrained shear strength from the CAU-tests is calculated as the deviator stress
divided by 2. The results are included in the Summary – Laboratory Test Results, Enclosure 1B.05.
4.4.18 Consolidated Drained Triaxial Compression Test (CID)
The Consolidated Drained (CD) triaxial compression tests on sand samples were performed isotropically as CID tests. The results of the CID triaxial tests are presented in
Appendix 1C.XI.
The friction angle from the CID-tests is calculated as the secant angle for each test. The
results are included in the Summary – Laboratory Test Results, Enclosure 1B.05.
4.4.19 Direct Simple Shear Test (DSSst)
Static direct simple shear tests have been performed on selected specimens of undisturbed cohesive soil. The results of the direct simple shear tests are presented in Appendix 1C.XIII.
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The peak shear stresses calculated from the DSS-tests are given in the Summary – Laboratory Test Results, Enclosure 1B.05.
4.4.20 CAU Triaxial Test Cyclic (CAUcy)
Cyclic triaxial tests have been performed on selected specimens of intact cohesive soil.
The detailed testing procedure is provided by GEO based on general experience (re. Section 4.5). The results of the cyclic triaxial tests are presented in Appendix 1C.XIV.
4.4.21 C14 Dating Result
C14 Dating has been performed on a single sample. Description and test result are presented in chapter 5.2.5., table 5.2 and in Appendix 1C.XV.
4.5 Comments to laboratory work
Laboratory tests have been performed as ordered in the extent possible, however a few
of the planned test were not possible due to mainly lack of sample material or the subsample was not deemed suitable for testing. The latter restriction was linked to the highly fissured and fractured limestone.
With the above mentioned limitations for the limestone samples, the performed UCS
tests are most likely not fully representative for limestone deposits since testing were
only possible to carry out on the more homogeneous parts of the limestone.
Effort has been made to ensure that geological descriptions are in agreement with results of classification tests, following the guidelines of the standards. All classification
testing were carried out after the geological description, and descriptions of samples
selected for classification testing were then compared with test results and adjusted, if
necessary. Depending on a geological evaluation, descriptions of samples close to the
sample tested have been adjusted also in some cases.
The advanced tests (CAU, CID, DSSst and CAUcy) have been initiated before results of
the classification tests and consolidation (Oe-IL) tests were available. The test specifications for the mentioned advanced tests have therefore been based on GEOs general
knowledge in respect of the formation to be tested.
5 SOIL CONDITIONS
The Danish part of the Kriegers Flak bank is composed of a rather complex sequence of
glacial deposits, including Interstadial deposits (i.e. sediments from a short, warmer period within a glacial period), as well as Lateglacial and Postglacial deposits, all of which
overly the Cretaceous Limestone. Enclosure 1A.03 presents the soil types along two longitudinal sections through the area. Photos of selected soil types and details are shown
on Enclosure 1G.01.
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5.1 Soil types
5.1.1
List of soil types
The soil types encountered in the 17 boreholes over the investigated area are listed in
Table 5.1 in chronological order with age.
Period
Code
Postglacial
Ma Pg
Fw Lg
Lateglacial
Glacial Upper Weichselian age
Sandnes Interstadial
Glacial Weichselian
age
Cretaceous
Ss Lg
Soil Type
Marine sand and organic sand
Glaciolacustrine
freshwater deposits
Solifluction sand
(flow till)
Geological description
Sand with shells, with local gyttja layers
Medium to high plasticity clay with laminae of
silt and fine sand
Fine to medium sand with peat
Medium to high plasticity clay with laminae of
silt and fine sand. Fine to coarse sand with
subordinate silt, clay or gravel
Medium to high plasticity clay with laminae of
silt and fine sand
Fine to coarse sand with subordinate silt, clay
or gravel
Mw Lg
Meltwater clay and
sand
Mw Gc
Meltwater clay and
silt
Mw Gc
Meltwater sand
Gl Gc
Upper Till*
Clay till, locally sand till
Fw Is
Organic clay and peat
Highly plastic, organic clay, with shell fragments. Peat
Gl Gc
Lower Till*
Clay till
Ma Ct
Limestone
Muddy white limestone, with flint nodules and
layers
Table 5.1. Soil types in the investigation area. The soil types have been listed chronologically, except for the glacial deposits that alternate through the Pleistocene.
Note *) The glacial till may contain cobbles, boulders or rocks though not registered in the boreholes.
5.2 Details on soil types
5.2.1
Marine Sand
The top unit of marine sand has been deposited during the Flandrian transgression.
The top unit mainly consists of non-graded sand deposited during the Postglacial. In the
central part of the area it occurs in thicknesses less than 1 m, while in the outermost
boreholes and in borehole KF-BH007 the thickness is between 1.3 m and 4.5 m.
5.2.2
Glaciolacustrine freshwater deposits
In Lateglacial time thinly laminated freshwater clay was deposited in the Baltic Ice Lake.
In borehole KF-BH011 and KF-BH016 there have been observed clays which are rich in
silt and fine sand laminae or streaks. These laminated clays have been deposited on top
of more silty Lateglacial meltwater deposits and clay tills and are interpreted as varve
deposits in the Baltic Ice Lake.
The transition from meltwater deposits to freshwater deposits in the Baltic Ice Lake is
most evident in KF-BH-016.
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5.2.3
Meltwater clay, silt and sand
These units have been deposited in ice-free environment during the melting of the glacier responsible for Prior Tills.
In borehole KF-BH009 and KF-BH012 the Lower Till is resting on top of 3 to 4 m medium
plasticity meltwater clay, probably deposited during the melting of an earlier glacial advance. Except for borehole KF-BH008, KF-BH012 and KF-BH015 the Lower Till is covered
by varying thicknesses of medium to high plasticity clay or poorly graded sand. The clay
often contains varve-like, thin silt and sand laminae, pointing to a meltwater or glaciolacustrine origin.
5.2.4
Upper Till
The Upper Till has been deposited during an Upper Weichselian glacial advance.
The Upper Till is very similar to the Lower Till. The boundary between the upper and
Lower Till has introductory been assessed based on water contents and/or strengths
measured by the pocket penetrometer; see borehole KF-BH001, KF-BH004, KF-BH005,
KF-BH006, KF-BH007, KF-BH008, KF-BH009, KF-BH010, KF-BH011, KF-BH013, KFBH015, KF-BH016 and KF-BH017. The water contents of the Upper Till are in most of the
mentioned boreholes higher than the water contents of the Lower Till. An inverse pattern
has been registered in the strengths measured by the pocket penetrometer, indicating
lowest strengths in the Upper Till. In Enclosure 1A.03 a rough indication of the boundary
between the Upper Till and Lower Till has been made. In most of the area this unit has
been intersected by several meltwater layers or lenses with thicknesses between 0.1 m
and 15.1 m.
5.2.5
Interstadial clay
This unit is probably meltwater clay, although it locally contains peat, organic clay with
shell fragments and iron sulphides, pointing to a non-meltwater origin, probably related
to an interstadial.
In borehole KF-BH004 a 0.5 m layer of organic clay with shell fragments have been observed with top at level -33.8 m. In borehole KF-BH014 a thin peat layer has been observed at level -34.7 m. C14 dating of the organic clay was carried out at the Radiocarbon Dating Laboratory at Aarhus University, Department of Physics and Astronomi. The
result is shown in Table 5.2. The detailed results are presented in Appendix 1C.XV.
Borehole
KF-BH004
Sample
17.10D
Depth
13.05 m
14C age (before present
Calibrated age
= AD 1950)
(IntCal09)
38400 ± 430 BP
~ 40850 BC
Table 5.2. Result of C14 dating.
This age lie within the Sandnes Interstadial, 42-32 thousand years before present
(Larsen (2006), p. 293).
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5.2.6
Lower Till
The Lower Till unit has probably been deposited during a Middle Weichselian glacial advance. The top of this unit appears to be quite planar, occurring at levels around -35 m
to -45 m over most of the area. In borehole KF-BH006 the top of this unit has been observed at level -50 m.
All boreholes in the area have penetrated this often silty or medium plastic clay till that
locally shows inclined limestone layers and smears; see borehole KF-BH005, KF-BH008
and KF-BH014. In most of the boreholes the pocket penetrometer indicates high or maximum values of undrained shear strengths. In all boreholes except for borehole KFBH009 and KF-BH012 the Lower Till is resting directly on top of the limestone. In borehole KF-BH009 and KF-BH012 the Lower Till is resting on top of a meltwater clay, probably deposited during the melting of an earlier glacial advance.
5.2.7
Limestone
Prequaternary rock composed of muddy, white limestone with many dark grey/black flint
nodules and thin layers. Locally the upper part shows evidence of glacial deformation.
In the entire area the Prequaternary rock is made of Maastrictian Limestone deposited
during the Late Cretaceous period. This deposit occurs very widespread in NW-Europe, in
the Kriegers Flak area it appears mainly as a muddy, white limestone with many dark
grey/black flint nodules and thin layers. The upper part of the limestone is locally showing evidence of glacial deformation. This unit has been found in the bottom of all boreholes, except for KF-BH006.
5.3 Tentative geological history
Based on the data presented on the borehole logs the following presents a tentative geological history for the Danish part of the Kriegers Flak area.
The Quaternary series overlying the Maastrichtian Limestone was formed during at least
two glacial advances that probably all took place during the Weichselian glaciation. Deposits from the advances equivalent to the Lower and Upper Tills are locally separated by
organic layers dated to Sandnes Interstadial. Thus, the Lower Till advance was probably
one of the two Mid Weichselian advances Ristinge or Klintholm. The Upper Till was possibly formed by either the Mid Danish, East Jylland or Bælthav advance, cf. HoumarkNielsen (1999, 2007) /4/ and /5/ and Larsen (2006) /6/.
5.3.1
Cretaceous deposits
The limestone in the area has been deposited in a Late Cretaceous sea with a high eustatic sea level and minor or no tectonic activities. The vast quantities of muddy limestone deposits indicate an enormous biological production and highly nutritious sea.
Borehole data indicate a SW-NE downward inclination of the limestone surface in the
order of 12 m. Local depressions have been observed in the limestone surface in the
order of more than 10 m; see borehole KF-BH003, KF-BH006, KF-BH009 and KF-BH012.
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These could be channel structures formed by flowing meltwater below or in front the ice
sheet. It is even possible that borehole KF-BH006 and KF-BH012 are located in the same
SW-NE trending channel structure.
5.3.2
Lower Till
A glacial advance probably in Mid Weichselian deposited the lower clay till on top of the
limestone and locally on top of meltwater deposits from earlier glacial stages; see borehole KF-BH009 and KF-BH012. Later the Scandinavian ice sheet melted away from the
Baltic area, and left a even and planar till surface behind.
5.3.3
Meltwater and glaciolacustrine freshwater clay
Subsequently the Kriegers Flak area was flooded by a lake, which possibly, from time to
time, was connected to the marine Kattegat sea, where, at about the same time, the
Skærumhede series was deposited, Houmark-Nielsen, M (1999). To begin with, the climate was still cold, and rather thick layers of meltwater clay and sand were deposited in
the lake. During this period, the climate was not entirely stabile and during warmer
stages plant and animal life invaded the area and left traces in the lake deposits as shells
and iron sulphide stains. In short periods the temperature was high enough to enable the
formation of organic layers. The age of these layers correspond with the Sandnes Interstadial, 42–32 thousand years before present. Later the climate again deteriorated, and
organic traces vanished from the clay.
5.3.4
Upper Till
In contrast to the Lower Till, this till shows frequent lenses and layers of meltwater clay
and sand. The till was formed during one or more late Weichselian glacial advances,
which overrode the medium to highly plastic and still relatively soft (and thus easily deformable) meltwater and freshwater clays of the preceding ice-free period. The Insterstadial deposits was thrust and folded into more or less irregular bodies of very variable
thickness. Glacial deformation is indicated in several ways, both by presence of contorted
layers and laminae, occurrence of till and meltwater sand bodies within the meltwater
clay, and by the fact that it is generally difficult to correlate the meltwater layers from
borehole to borehole with regards to lithological composition and thickness. In the northwestern part of the area no or very thin occurrence of meltwater deposits have been
observed.
In the central part of the area, in boreholes KF-BH004, KF-BH005 and KF-BH007, the till
sequence shows a conspicuous rise in water content between level -26.0 m and -33.5 m,
which might indicate that the Upper Till is, at least in some places, composed of two different tills probably formed during two different glacial advances.
5.3.5
Lateglacial deposits
The retreat of the last glacier over the Kriegers Flak area revealed a landscape consisting
of an undulating surface and a low-lying plain to the Northeast. It was still cold and during the summers the surface soil of the permafrozen ground thawed and in some places
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slid down the slopes in the landscape forming solifluction soil (flow till), which is only
found in borehole KF-BH005.
As temperatures rose and ice melting increased, the rising Baltic Ice Lake flooded the
area, and glaciolacustrine clay with silt and sand varves was deposited. Today this clay is
found in depressions, and in the periphery of the elevated Kriegers Flak area, as up to
3.2 m thick deposits; see borehole KF-BH011 and KF-BH016. Originally the clay must
have covered most of the area, with the same approximate thickness, but later erosion
has removed most of it again. This could have happened during Preboreal time, at the
beginning of Postglacial time. Then the Baltic Ice Lake withdrew from the Kriegers Flak
area, enabling waves on the lake shores to rework the lake deposits – bringing the clay
in suspension and removing it from the silt and sand, which was left behind. Or a similar
reworking could have happened during the Flandrian transgression later in Postglacial
time.
5.3.6
Postglacial deposits
The Flandrian transgression introduced the present marine conditions in the Baltic. When
the sea flooded the Kriegers Flak bank, its surface was reworked by waves and surf, finegrained material was eroded and removed from the area, notably the glaciolacustrine
clay of the Baltic ice lake (see Section 5.3.5), and only gravel and cobbles were left behind. Later, when the water depth had increased, sorted to well sorted sand was deposited in moderate thicknesses, and more fine-grained and organic material was deposited
here and there. Marine sand sedimentation processes are still operating today.
Encl. 1A.03 presents the geological model along two longitudinal sections, a northern
and southern. As may be seen, the top limestone boundary slopes gently to the NE,
while top Lower Till is almost horizontal.
6 Comparison with the geology from the geophysical investigation
The soil layers and soil boundaries found from the borehole logs have been roughly compared to the previous geophysical investigation and interpretation made by Ramboll DK,
in the ref /7/. Ramboll DK has identified different geological units based on the seismic
results. The units are listed in Table 6.1.
Unit
Holocene Marine 1 (HM1)
Holocene Marine 2 (HM2)
Holocene Marine 3 (HM3)
Flow Till (FT)
Upper Till (UT)
Kriegers Flak Clay (KFC)
Lower Till (LT)
Cretaceous (C)
Table 6.1. Geological Units identified by Ramboll DK
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6.1.1
Post- and Lateglacial deposits
The Postglacial deposits observed in the boreholes are identified as the 3 Holocene units
(HM1-3) and the Lateglacial deposits are identified as the FT unit and consist of soft sediments.
The combined depth to base of these Post- and Lateglacial units are in general less than
4 meters in the investigation area and in general the interpreted depths to base of the
units in the geophysical investigation match the thicknesses of the deposits observed in
the boreholes within 1 m. Exceptions are borehole KF-BH001 and KF-BH011 with respectively approx. 3 m and 4 m difference between the geophysical interpretation and the
geotechnical logging.
6.1.2
Glacial deposits (Upper and Lower Till)
The Glacial deposits are identified as the UT, KFC and the LT units. In general, the base
of the Lower Till (top of Cretaceous Limestone) in the investigation area match the interpreted depth to base of the LT unit in the geophysical investigation within 4 m. Exceptions are borehole KF-BH006 in which the base of the Lower Till has not been observed
and KF-BH009 with approx.8 m difference between the geophysical interpretation and
the geotechnical logging.
The boundary between the UT, KFC and LT units are too uncertain in the geophysical
interpretations and a comparison is therefore not performed.
6.1.3
Cretaceous Limestone
The base of the Cretaceous Limestone has not been observed in the geophysical investigation or the geotechnical logging. The top of the limestone coincides with the base of
the Lower Till deposit which in general match the interpreted base of the LT unit from the
geophysical investigation (see Section 6.1.2).
7 Typical geotechnical characteristics
For each investigation point the laboratory classification tests and advanced tests have
been listed and related to the corresponding geological soil unit to form a “mini database” of the geotechnical parameter variation. Based on this this database typical values
or ranges of the geotechnical parameters have been identified and tabulated.
The values are presented in Table 7.1 and Table 7.2. The two tables are as such “identical” just divided to cover all encountered soil units. Table 7.1 includes the post- and late
Glacial units and Table 7.2 presents the Glacial and Cretaceous units.
The ranges in the tables include minimum 5 single data point if less data are available
the number of available tests results are indicated together with the values.
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Description of the soil types can be found in Table 5.1 and details of the individual test
are all listed in the overall summary in Enclosure 1B.05.
It shall be noted that the boundary between the upper and Lower Till is not clear defined
in all boreholes. The boundary in each borehole has been established based on geological
description, index tests and CPT results. Due to the above uncertainty in the boundary
the geotechnical classification of these two “formations” are therefore subject to uncertainties.
The form of presentation is not a statistical work up of all data for the individual parameters leading to determination of characteristic design values for each soil type. The
presentation of data in Table 7.1 and Table 7.2 is prepared as guide to get a quick overview of the geotechnical parameter variation for each geological soil type to be used only
for initial engineering purposes.
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Parameter
Unit
Marine sand
Glacio-
Meltwater
and organic
lacustrine
clay
sand
freshwater
Meltwater sand
deposits
(Ma Pg)
Water content
(w)
Bulk density
(m)
Medium grain size
(d50)
Uniformity coef.
(U)
Dry density
(Max/Min)
Clay fraction
(<0.002 mm)
Plasticity index
(Ip)
Carbonate cont.
(Ca)
Undrained Shear
Strength
(cu)
Friction Angle
(ϕ’)
Unconfined Compression Strength
(σc)
%
Mg/m3
mm
-
Mg/m3
(Fw Lg)
10-81
22-82
#1,2
(3)
1.7-2.1
NA
1.6-3.9
(Mw Lg)
18-57
15
(1)
1.7-2.0
2.0-2.2
(4)
(2)
0.002
0.002
0.088
(1)
(1)
(1)
NA
NA
11.3
(3)
0.178-0.6
(Mw Lg)
(1)
1.45/2.0
%
%
%
kPa
NA
kPa
1.57/2.11
(1)
NA
49-63
46
2
(2)
(1)
(1)
NA
22-37
12-36
NA
(2)
(2)
0.8-8
7-23
13
15
(2)
(1)
(1)
NA
19-56
NA
15
(1)
Degree
NA
37
(2)
NA
NA
NA
NA
NA
NA
(1)
NA
Table 7.1. Post- and late glacial units with geotechnical parameter values
Notes:

Value shown in brackets () indicates the number of available test results

The strength parameters cu and ϕ’ are based on the triaxial tests

The Solifluction sand (SS Lg) is not included (no test results)
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Parameter
Water content
(w)
Bulk density
(m)
Medium grain size
(d50)
Uniformity coef.
(U)
Dry density
(Max/Min)
Clay fraction
(<0.002 mm)
Plasticity index
(Ip)
Carbonate cont.
(Ca)
Undrained Shear
Strength
(cu)
Friction Angle
(ϕ’)
Unconfined Compression Strength
(σc)
Unit
%
Mg/m3
mm
Meltwater
Meltwater
clay and silt
sand
(Mw Gc)
(Mw Gc)
(Gl Gc)
5-31
#1
(2)
1.9-2.4
1.9
#2
(1)
0.001-0.023
0.145-0.393
0.002-0.364
NA
1.8-3.8
2.2-64.4
Lower till
Limestone
(Fw Is)
(Gl Gc)
(Ma Ct)
7-26
27
7-32
19-37
1.9
2.1-2.6
1.6-2.1
(1)
#5
#6
0.009
0.007-0.128
NA
NA
NA
NA
NA
NA
NA
12-36
NA
6-21
NA
2-26
NA
(1)
2.1-2.7
(1)
(3)
NA
1.46/1.98
NA
15-66
NA
6-38
25
#4
(1)
6-25
28
Mg/m3
8-38
%
NA
(1)
3-21
%
kPa
Organic clay and
peat
13-38
-
%
Upper till
3-15
1-22
#3
<0.1
(1)
93-385
NA
47-620
NA
137-1235
50-2046
NA
34-42
NA
NA
NA
NA
NA
NA
NA
99-4091
Degree
kPa
(2)
NA
NA
Table 7.2. Glacial and Cretaceous units with geotechnical parameter values
Notes:

Value shown in brackets () indicates the number of available test results

The strength parameters cu and ϕ’ are based on the triaxial tests
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8 REFERENCES
/1/
Danish Geotechnical Society Bulletin No. 1E (1995): A Guide to engineering
geological soil description.
/2/
Level of seabed provided in email from Client. Email dated 2013-06-27.
/3/
Lunne, T., Robertson, P.K. & Powell, J.J.M. (1997). Cone penetration testing in geotechnical practice. Blackie Academic & Professional, London.
/4/
Houmark-Nielsen, M. (1999): A lithostratigraphy of Weichselian glacial and
interstadial deposits in Denmark, Bull. Geol. Soc. Denmark, vol. 46, pp.
101-114.
/5/
Houmark-Nielsen, M. (2007): Extent and age of Middle and Late Pleistocene glaciations and periglacial episodes in southern Jylland, Denmark,
Bull. Geol. Soc. Denmark, vol. 55, pp. 9-35.
/6/
Larsen, G. (2006): Naturen i Danmark – Geologien, Gunnar Larsen (ed.),
549 pp, Gyldendal (in Danish).
/7/
Ramboll (2013): Kriegers Flak Geotechnical Location Planning Report.
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