The suitability of the method is more than other compaction techniques dependent on the grain size distribution and fines content. The material needs to be permeable enough to allow quick drainage of the added water during the compaction process. In practice this means less than 10% fines and less than 2% clay. During field trials at the start of a project, the horizontal influence zone is determined under different operational procedures and related to the project requirements. The outcome results in a center to center distance, also referred to as grid size.
Why it's used
Compaction is required to mitigate liquefaction risks or improve the bearing capacity and settlement behavior under loading of the underground. CVC compaction is often used on new reclamations to compact the subsoil up to requirements to avoid liquefaction under an earthquake.
The CVC results and required effort are related to the soil type, fines content and requirements. Applying Vibro- compaction will result in the following effects:
- Soil densification due to vibration and particles re‐organization
- Friction angle increase
- Stiffness increase
- Bearing capacity increase
- Liquefaction mitigation
- Limitation of settlement when applying load
Cofra Vibro Compaction is used in the following markets:
- Infrastructure: The CVC technique is for example used for the compaction of embankments for roads, railways, runways and aprons for airports and port areas. The compaction can in this case be related to liquefaction mitigation but also to improve the load settlement characteristics of the substrata under dynamic loading (transport of heavy equipment or reduce the long term impact of impacts)
- Dredging and land reclamation: CVC is often used to compact the deeper sections of reclamations up to specification
- Mining: CVC can be used to compact thick spoil deposits before the rehabilitation of an area.
- Construction: Cofra vibro compaction is used in the construction industry to mitigate liquefaction risks
- Liquefaction mitigation: CVC is used for liquefaction mitigation in areas where loose saturated granular soil occurs below a depth of 7 to 9 meters
The following soil types are suitable for the use of CVC: