Øysand research site: Geotechnical characterisation of deltaic sandy-silty soils

Abstract

This paper describes the geology and geotechnical engineering properties of the fluvial and deltaic gravelly-sandy-silty sediments at Øysand, Norway. Geophysical and geotechnical site investigations carried out between 2016 and 2018 at the site are presented. Field testing included state-of-the-practice and state-of-the-art soil characterisation techniques such as total sounding, seismic cone penetration testing, seismic flat dilatometer, multichannel analysis of surface waves, electrical resistivity tomography, ground penetrating radar, piezometers, thermistors strings, slug tests, and permeability tests using a newly developed CPT permeability probe from NGI. Several sampling techniques were used at the site to assess sample quality. Laboratory testing consisted of index tests and advanced triaxial tests with bender elements to estimate shear strength and stiffness. Data interpretation, engineering soil properties and state variables derived from this analysis are presented, along with comments on data quality. Engineering problems investigated at Øysand so far and discussed in this paper are related to: the impact of using different CPTU types, sample quality assessment by obtaining soils with state-of-the-practice and state-of-the-art techniques (such as gel-push sampler and ground freezing), and frost heave susceptibility.

Keywords

• gravelly sand
• silt
• in situ testing
• sampling
• laboratory testing
• site characterization
• permeability