Field and Laboratory Test Results from NGTS soft clay site – Onsøy

Abstract

In 2017, the Norwegian GeoTest Sites (NGTS) project established five research sites, one of which is the new Onsøy soft clay site located close to Fredrikstad city. This report contains all results from field and laboratory tests related to the NGTS soft clay test site to revision date. In-situ methods include electrical resistivity tomography, multichannel analysis of surface waves, total soundings, rotary pressure soundings, cone penetration testing with and without seismic and electrical resistivity measurements, dilatometer with seismic measurements, self-boring pressuremeter, electric piezometers, thermistor string, hydraulic fracture testing and earth pressure cells. Soil samples were obtained using different sampling techniques such as Sherbrook Block sampler, in addition to 72 mm piston sampler and 54 mm combined piston sampler. Laboratory tests such as multi sensor core logging, index testing, cyclic and monotonic, consolidated and unconsolidated triaxial tests, bender element tests, oedometer tests with constant rate and incremental loading and direct simple shear tests have been drawn upon. Different projects, other than NGTS as well, have been performing field tests, sampling and laboratory testing. However, all the field work and laboratory work have been combined to identify the new test site at Onsøy and characterize the clay at the new test site.