Characterisation and stress-strain behaviour of silt

Offentlig prosjektsammendrag

In geotechnical engineering, the behaviour of clays and sands is generally well documented. For silt, the situation is entirely different. Yet there are many constructions founded on silt. Silt is an intermediate soil, between sand and clay in terms of grain size and permeability. The limited knowledge on the stress-strain behaviour of silt, the effects of disturbance while sampling and the expected dilatant behaviour of silts create significant uncertainties for design of foundation on silt. So far, the design for constructions on silt has been conservative due to the uncertainties in the parameters and the behaviour of silts. The primary objective of this research is to develop the behaviour of silts under different types of loading in order to help designers select representative values of shear strength and deformation modulus for in situ silt. The project will develop the stress-strain-strength behaviour of natural silt, base on well-controlled laboratory and in situ tests. The effects of sampling disturbance will be quantified. Systematic testing will be done on Halden silt under different stress and sampling conditions in the laboratory and in situ. Recommendations will be made on the values of the parameters to use for design on silts. The project has four key parts: 1) sampling with different samplers and measurement of indicators of sampling or other disturbance, 2) laboratory test program; 3) in situ measurements; and 4) development of the relationship(s) stress-strain-strength-disturbance for silts.