References
Storage platform - Montereau
FRANCE, 2007
Trenchmix used as ground treatment in preparation for the construction of a storage platform.
Solétanche Bachy was awarded the contract for the construction of a logistics platform at the Montereau river port (77). The platform measures approximately 32,400m² and comprises 4 areas that bear a maximum load of 6 t/m², separated by traffic lanes. Ground treatment works consisted in the use of Trenchmix (sections of soil mixed with a hydraulic binder) and the construction of a load distribution blanket. The Client opted for the alternative solution using Trenchmix because of its technical and financial competitiveness compared with compacted column foundations and with rigid inclusions.
Ground surveys revealed a very heterogeneous subsoil along the lateral extension with a capping of old alluvia at depths varying from 2.6 to 5.2m below the natural ground surface. The water table is approximately 3m below the natural terrain.
After stripping off the topsoil, a 0.4m thick working platform was constructed on land treated with lime. This platform was designed to provide access for various site vehicles and for the purpose of deploying the "dry method" process:
- the hydraulic binder in the form of cement powder is poured into a shallow preliminary trench;
- a tractor and a trailer are driven over the area several times in order to spread the hydraulic binder powder;
- Trenchmix proper: the soil was broken down and mixed in the trench with the previously deposited binder.
The upper stratum of the load distribution blanket consisting of a layer measuring approximately 0.6m thick of material treated using the binder consisting of lime + cement was then laid. The 0.4m working station acts as part of the load distribution blanket, thus providing a 1m thick distribution layer. No foreign materials were required for the completion of these works
Up to 500m of Trenchmix with an average depth of 4.5m was put in place per day. The Trenchmix component took less than 6 weeks to complete.
MAIN QUANTITIES:
• Approximately 60 Trenchmix trenches measuring 180 linear meters.
• Ground treated: 33,000m3
Techniques
Soil-improvement techniques involve changing soil characteristics by a physical action, such as vibration, or by the inclusion or mixing in the soil of a stronger material. The aim of this process is as follows:
- increase the load-bearing capacity and/or the shear strength,
- reduce both absolute and differential settlements or in certain cases, accelerate them,
- to mitigate or remove the risk of liquefaction in the event of an earthquake or major vibrations.
Soil mixing uses a wide range of techniques to inject binder agents to mix with the soil and form columns, for example, to reinforce the ground for subsequent construction. The type and amount of binder will determine the hydraulic and mechanic characteristics of the soil.
Ouvrages
Soletanche Bachy can deliver a building platform ready for construction
Voyage au coeur de l'ingénierie de pointe
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