6.003 - Finland - Sormero - 1987

Bypass, Somero FINLAND – 1987

Tunnels (06-003-A)

06-003-A – pag 2/2

Problem On a section of the bypass around Somero, 3 underpasses were to be built. Due to the soft subsoil and for cost reasons it was decided to use direct foundation to build the concrete structures on the soft soil. In the approach areas to the structures and the roads crossing above them, Leca® was used as lightweight fill to reduce the load.

Cubic Area: 3,000 m3.

Load: No data.

Performance Composition

Measurements Settlement measurements by topographic levelling: –› 4 cm settlement in the first 6 month, no more recent data.

Road bed No data.

Base Leca® wrapped in geotextile, thickness of up to 5 m.

Flaws/damage Type: no data.

Time: --

Subsoil 20-30 m fat clay; Up to 10 m: water content around 100% –› undrained shear strength: 25 kN/m2; At lower levels: water content around 70% –› undrained shear strength: 35 kN/m2.

Maintenance work No data.

Construction

Clay crust

Clay W = 70 – 100% Cu = 20 – 35 kN/ m2

Leca®, wrapped in geotextile

Cross-section of concrete structure.

Clay crust

Clay crust

Clay W = 70 – 100% Cu = 20 – 35 kN/ m2

Leca®, wrapped in geotextile

Cross-section of the ramp section.

Building method 1. Direct foundation of the concrete structure on the clay; 2. Backfill of the structures + foundation fill with Leca®.

Appraisal/Experiences Settlement probably in the subsoil; at least a reduction in settlement achieved in comparison with conventional building methods.

Quality control No data.

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