Dynamic Replacement is an alternative to the more commonly used Dynamic Compaction technique, utilising dynamic impact techniques to improve soils at the boundary between fine- and coarse-grained materials.
Dynamic Replacement utilises tracked crawler cranes, dropping compaction weights from heights of up to 20.0m. The depth of influence achieved is in the typical range of 5.0m – 8.0m, potentially increasing to as much as 15.0m, dependent on drop heights, tamper weight and soil conditions.
With prior approval Dynamic Replacement can utilise recycled aggregates, offering environmental sustainability benefits.
The Dynamic Replacement Process
Ahead of commencement on site GeMech will complete a detailed ground improvement design and prepare a dynamic compaction layout based on a set of construction issue foundation drawings – supplied to GeMech in DWG format by the Client.
Step 1 – Prior to the crane arriving to site the client surveys the area for services and prepares a suitable working platform at either top of foundation level or underside of slab level and drives a numbered pin into the working platform at each compaction point location.
Step 2 – A health and safety briefing will take place, the rig will be prepared to work, and moved to the first pile position.
Step 3 – A compaction trial is carried out, to determine depth of drop weight penetration and saturation energy, through measurement of the ground heave profile. This will inform the compaction process across the working areas.
Step 4 – Stone is delivered to site and tipped on the working platform, in a stockpile positioned close to the piling rig. GeMech will move stone from the stockpile to the individual columns using a 360 excavator.
Step 5 – The shaped drop weight is positioned over the compaction point and lifted to the predetermined drop height. When at the required height, the weight is dropped in free fall to impact the surface of the working platform. This process is continued until the require depth of penetration, or saturation energy is achieved.
Step 6 – Stone is placed in the resultant void, with each layer successively compacted by the drop weight during the compaction process. This process is repeated until all primary compaction points have been completed.
Step 7 – A lighter, flat bottomed, drop weight is attached to the crane, and the entire surface of the working area. This process recompacts the near surface soils which are prone to disturbance during the initial higher energy compaction pass.
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FAQs
Q – How much does dynamic compaction cost?
A – The cost of dynamic compaction can vary widely depending on factors such as site conditions, project size, and location. To get an idea on costs, speak to our ground improvement specialists to get a more accurate quote.
Q – What equipment is used in dynamic compaction?
A – Dynamic compaction and dynamic replacement is carried out using a 9.0t – 15.0t weight, dropped in free fall from heights of 10.0 – 20.0m using a 65.0t + tracked crawler crane. When using GeMech’s modified dynamic replacement system, the crane will be supplemented by a tracked excavator, which is used to place imported aggregate into the compaction voids.
Capabilities:
- Depth of influence up to 8.0m.
