When land is reclaimed from the seabed or the in-situ soil does not fulfil the requirements of bearing capacity, lateral stability and liquifaction potential, ground improvement techniques with Vibrolance offer a qualitative and economical solution.
PTC has developed a complete range of equipment for the following ground improvement techniques:
VIBROCOMPACTION - Technique used in granular soils, for land reclamation and sand compaction. The Vibro compaction technique is used in granular soils with limited fines content. It uses the Vibrolance sustained vibrations to rearrange the soil particles of non-cohesive soils into a denser state. The action of the vibrator reduces the inter-granular forces between the soil particles, allowing them to move into a more compact, denser configuration.
STONE COLUMNS - Technique mostly used for cohesive saturated soils. It consists in installing and compacting in the ground load bearing columns made of gravel or crushed stone, following a grid pattern previously determined by a test trial.
There are two methods to produce stone columns and they differ mainly in the system that is used to release the stones into the ground:
TOP FEED METHOD:
It is the most cost-efficient ground improvement method. It requires the use of a free hanging vibrolance that penetrates the ground thanks to the lateral vibrations emitted by its tip. During penetration, the soil is laterally compacted by displacement allowing the vibrolance to create the hole that will contain the stone column.
When the desired depth is reached, the vibrolance is withdrawn to allow the stones to be released from the ground surface into the hole. The stone feeding is done by stages to allow a better compaction of the entire stone column. Each time the hole is filled with stones, the Vibrolance goes down again to compact them. This process is repeated several times until the stones reach the surface.
BOTTOM FEED SYSTEM (BFS):
The BFS system controls the length and the diameter of the stone column, better than the Top feed system. In addition, there is no risk of soil collapse while the stone is released, because the Vibrolance is not withdrawn from the ground until the stone column is finished. Thus, the BFS system allows the contractor to have a continuous production process that results in higher productivity and time savings.