Assessment of Soil Stabilisation using Electrical Resisitivity Tomography

The use of ground improvement methods is growing increasingly common to allow infrastructure expansion in areas of low stability soils. Ground improvement methods offer great economic benefits compared to alternate measures and are preferable from an environmental and sustainability perspective since they minimize the need for transport and the use of natural resources. However, there is a large demand for better and more quantitative methods of ground improvement quality assurance. Quality assurance can practically be divided into two steps, where the first step is initiated immediately after mixing of binder into the soil to assure treatment of the entire targeted volume, and to identify any areas that need to be rectified. The second step, monitoring of the shear strength, cannot be done until sufficient hardening has taken place.

This project focuses on the first step, to be performed in immediate relation to injection of binder into soil, using electrical resistivity tomography (ERT) as a quality assurance method. Previous tests that have been carried out indicate that the method appears be effective at delimiting soil volumes that have been treated with binder from untreated soil volumes. Since the treated soil resistivity shows immediate change after injection of binder, the method could be used to quickly control the ground improvement result, allowing for direct rectification while equipment and personnel are still on-site. Testing and verification of the method are to be made in various geomaterials and scales, including full scale field tests for different kinds of ground improvement. Further, the ERT method is to be adapted for the application, into a fast and practically applicable alternative for quality assurance of ground improvement.