Geotechnical properties of Rasht clay and silt in Northern Iran: Fid-Bau Portal

Geotechnical properties of Rasht clay and silt in Northern Iran

Akbarzadeh Kasani, Hossein / Eslami, Abolfazl

Owing to stratified profile of the sedimentary soils and shallow groundwater table in the city of Rasht, clay and silt soils possess different consistencies in various locations. Excessive consolidation settlement of the clay and silt governs geotechnical design of structures built in the city. This study aimed at characterising geotechnical properties of Rasht clay and silt from the upper 10 m. It comprised of constructing a database by collecting previous subsurface investigations at 21 project sites (including 70 boreholes), boring four test pits along with laboratory experiments and statistical analyses of the data. Properties investigated herein included bulk unit weight, specific gravity, natural water content, clay fraction, Atterberg limits and plasticity parameters, SPT N value, shear strength and stiffness and consolidation properties. Variation of these properties with depth was highlighted. Consistencies of the clay and silt specimens were determined. Laboratory strength and stiffness values were correlated to SPT N values. Rasht clay and silt were compared to other well-documented fine-grained deposits in literature. New relationships were established to estimate compression and recompression indices of the clay and silt from their index properties.