Decrease the likelihood of cost overruns
Underground construction works are often associated with great uncertainty about the ground conditions, especially if the projects cover large areas. Choosing the right method is easier after having seen the material composition, especially when it comes to rock fracture filling, frictional material, moraines, talus, rockfill and mixed ground in general.
For some projects it is not possible to take good traditional samples due to ground conditions. The reason for core loss may be gravel or stone disabling sampler penetration, water flushing material away, simply very loose material or lack of friction. These projects may also be the cases in which the project planning would benefit the most from good quality undisturbed samples.
The uncertainty remains through all design phases of the project and may be critical for the choice of alignment, solution, method, design and execution. Often the "unforeseen" ground conditions results in cost overrun and ends in court. GEOFROST Coring removes uncertainties associated with the ground conditions.
Best sample quality in the market
There are many methods to retrieve undisturbed samples of clay and clay materials not containing stones and gravel. We do not know any other method obtaining as good quality as performed by GEOFROST Coring if the ground for example consists of poorly graded frictional soil, contains gravel or is frozen.
Geofrost Coring delivers extraordinary good sample quality in all ground conditions. We are market leading in all soils except clay.
Lab tests with in situ conditions
We perform all routine investigation like density, water content, salt content, grain size distribution and plasticity limitation, which together ensures correct classification.
We obtain correct testing results because the original properties are preserved all the way from sampling until ready built in for testing in laboratory. Grain structure, water content and permeability are kept unchanged by GEOFROST Coring. The tests are run with in situ confining pressure, in situ pore pressure, in situ temperature and in situ sample structure.
Correct strength- and deformation properties provides an important basis for good decision making in the project.
For frozen ground we investigate strength and deformation properties as well as the thermal properties. This is used for permafrost design and for designing frozen structures established by ground freezing.
From some ground conditions it is difficult to obtain representative material, and undisturbed samples have been unthinkable. Geofrost Coring is a sampling method making undisturbed samples possible where before out of reach.
Fill is often a mix of different soils and materials. GEOFROST Coring makes it possible to core the fill, assuming they are drillable. Metal objects may be a problem.
Silt, sand and gravel
Undisturbed samples from pure frictional soils have long been a challenge with ordinary geotechnical sampling. Now we also take undisturbed samples of loose poorly graded sand.
GEOFROST Coring undisturbed samples are preserved until lab testing. The undisturbed sample will yield exact degree of compaction and permeability in addition to strength and deformation properties.
Talus and moraine
Mixed soil containing more or less stones in a fine grained matrix have been a challenge. Now sampling in these soils may be done by GEOFROST Coring.
Soil - rock contact zone
GEOFROST Coring can penetrate stones and rock and at the same time capture the fines. This enables closer examination in laboratory of the contact zone and also of rock fill compaction and layering, as well as testing of undisturbed samples.
Rock fracture inclusions
Often it is difficult to tell what kind of filling there is in the rock fractions, because it tends to be washed out by the drill fluid of standard coring methods.
With GEOFROST Coring fracture filling is captured, also empty cavities and water filling.
Before construction work can take place in urban areas, the ground has to be classified according to degree of contamination. Standard sampling capture solid contamination while liquid and gaseous phases are more problematic.
With GEOFROST Coring all phases are locked in place in situ, making the samples showing exact position of any contamination.
Permafrost and seasonal frost
GEOFROST Coring takes permafrost samples without thawing the surface and disturb the sample. When temperature is close to thawing as often is the case in marine permafrost sediments with pore water containing salt, it has been extremely difficult to get good quality samples.
In areas with seasonal frost GEOFROST Coring through the layers containing ice lenses may add new knowledge to how winters with different temperature variations affect the buildup of ice. This can be documented by undisturbed sampling of ground with ice lens inclusions.
Verification of design parameters may be done by GEOFROST Coring through the frozen structure and then test the frozen samples in laboratory.
For engineering purposes it has always been a need for classification of the different soils and rock formations, and to find parameters to use in calculations.
Classification and description
On samples provided by GEOFROST Coring, a much better classification may be done compared to classification just by material received by augring or drill cuttings. Porosity and density may be determined where earlier only qualified guessing took place.
Tests in unfrozen state
GEOFROST Coring enables performing lab tests on material as it was in situ. The undisturbed frozen samples are robust, and can easily be handled for preparation in the apparatus. Confining pressure like in situ is put on sample before thawing. With confining pressure, pore pressure and temperature as in situ, the sample will be ready for the real test. This enables new possibilities to find strength and deformation parameters of both frictional soils and mixed soils, as well as finding true permeability properties in newfound critical layers.
Tests in frozen state
By Geofrost Coring samples are frozen by ground freezing and may be tested directly to find strength parameters as well as thermal properties. In situ conditions are already taken care of by GEOFROST Coring, and testing frozen structure material can start right away.
What we deliver
- Geotechnical advisory
- Plan for sampling
- Undisturbed samples with GEOFROST Coring
- Transportation of samples to the laboratory
- Storing samples
- Laboratory testing
- Geotechnical laboratory report
Soil and rock investigation
GEOFROST delivers all services from geotechnical advisory, through drill plan giving numer and position for investigation holes, untill a complete geotechnical data report, with photo documentation, soil classification and test results.
Where we operate
We offer our services worldwide, including GEOROST Coring.
Anne-Lise Berggren, Ph.D., M.Sc
Senior geotechnical specialist
(+47) 95 29 29 30
With brief overall project info, we quickly provide rates and price estimates on request.