| 1. |
- Dahlin, Torleif, et al.
(författare)
-
ASSERT - Kontroll av markstabilisering med resistivitetstomografi (ERT)
- 2023
-
Ingår i: ; , s. 219-228
-
Konferensbidrag (refereegranskat)abstract
- Soil stabilisation is becoming increasingly common for the development of areas withpoor bearing capacity. However, there is a need for better and volume-wide controlmethods for quality assurance. The control methods can be divided into two steps,where the first takes place in immediate connection to the mixing of binders to checkwhether the entire intended volume has been successfully treated, or whether thereare zones that need completion. The second step focuses on the strength of thestabilised volume and assumes that the binder has cured.The R&D project ASSERT focuses on quality control using electrical resistivitytomography (ERT). The idea is to use the method in immediate connection with themixing of binders to delineate the soil volume that has been treated with binders fromuntreated parts. ERT could then be used to quickly check the results of thestabilisation, so that supplementary measures can be taken in zones of insufficienttreatment while personnel and equipment are in place. Furthermore, there is potentialfor volume-wide quantification of strength growth via correlation between change inresistivity and change in strength during the curing process, but this would probablyneed to be done on a site specific basis.Testing and verification of the method takes place in different geomaterials in thelaboratory and in the field, including full-scale tests for different types ofstabilisations. Furthermore, method development and adaptation for the applicationare included, so that the method becomes sufficiently robust and fast to be usedroutinely in a sustainable manner. Field trials have been carried out by installingelectrodes in lime-cement columns and jet columns in direct connection to thestabilisation. Laboratory tests have so far been carried out for lime-cementstabilisation of clay and for stabilisation of dredged masses.
|
|
| 2. |
- Dahlin, Torleif, et al.
(författare)
-
Novel electrode design for non-destructive resistivity measurement on material in geotechnical standard sample cylinders
- 2023
-
Ingår i: Procs. Near Surface Geoscience 2023.
-
Konferensbidrag (refereegranskat)abstract
- We present a novel design of an electrode arrangement for measurement of the resistivity of soil samples contained in a sample cylinder used in standard geotechnical site investigations in Sweden. The objective is to make it possible to measure the resistivity of the same samples that are to be used for mechanical tests, without disturbing the samples in order to get unbiased mechanical test data. A design with four piece-of- pie shaped electrodes integrated in the lids in each end of the sample has been tested and evaluated. Temperature sensors are embedded in the electrode lids to allow temperature compensation of the measured data.Alternative electrode designs were modelled numerically with the finite element method (FEM) prior to the prototype manufacturing. Measurement tests with water filled sample cylinders show that stacking and reciprocal errors can be kept below 1% provided that suitable measurement settings and sequences are used. The geometrical factors depends on the distance between the electrodes in each end of the cylinder, i.e. varies with the length of the sample, and must be determined experimentally or via FEM modelling.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Olsson, Per-Ivar, et al.
(författare)
-
ASSERT - Kontroll av markstabilisering med resistivitetstomografi
- 2020
-
Ingår i: ; , s. 1-10
-
Konferensbidrag (refereegranskat)abstract
- Ground improvement with lime-cement pillars is becoming increasingly common in the Nordic countries for exploitation of areas with poor stability. However, there is a need for non-destructive methods for volumetric quality control of the ground improvement. The quality control can be divided into two steps where the first include quality control at the installation process with monitoring of production parameters such as rotation and penetration speed, air pressure and binder feed rate. The second step involves determining the spatial continuity and the mechanical properties of the treated subsurface after curing by for example a reversed pillar penetration test, complete exposure or core drilling. ASSERT (Assessment of Soil Stabilization using Electrical Resistivity Tomography) is an on-oing research project with focus on quality control in direct connection with mixing of the binders based on electrical resistivity tomography (ERT). The ERT-method has in several cases been shown to efficiently differentiate treated soil from untreated. Hence, is the method an interesting option for direct and rapid volumetric quality control of the stabilized soil so that zones which needs to be supplemented can be identified at production stage while personnel and equipment are at site. The ASSERT project involves test and verification of the method in different geological environments and scales, including full-scale tests for different types of stabilization techniques. Additionally, method development and adaptations to make the quality control applicable are also included in the project to enable a robust, rapid and sustainable use in routine operations.
|
|
