Preparing for a new build on your vacant land takes a considerable amount of planning and designing. The first step in the process usually involves hiring a geotechnical engineering team to perform the necessary soil assessments and tests to determine if your land can handle the weight of your intended build.
The soil test Melbourne developers and builders have to perform is essential for obtaining the required building permits. The next step is to have an engineer use the data from these tests to choose the best building materials and techniques for your build. Despite this, there is still a wide range of things that can go wrong. One of the more common of these is compaction failure.
Understanding What Compaction Failure is
To understand what compaction failure is, one first needs to know what compaction is in the building context. Essentially, soil compaction in building refers to the general process of mechanically pressing soil particles as close together as possible. The goal here is to remove air and water.
Compaction is done to create a thicker, denser, and stronger foundation. When compaction is done correctly, the result is a more stable foundation that goes a long way toward preventing subsidence, settling, and eventual structural failure.
The goal here is to create a solid base tailored to the type of structure you need, which means the foundation should be able to hold the weight of the intended structure, even in events such as heavy rainfall and potential floods.
Compaction failure occurs when the soil beneath the structure is unable to support and hold the building’s weight and any associated loads. This happens when the density is rendered insufficient, causing the soil to move, often resulting in potential structural damage.
Assessing the Causes of Compaction Failure
When it comes to assessing the root cause of compaction failure, it’s essential to point out that it’s very rarely one specific reason. Experts advise that a failure of this magnitude is often attributed to a combination of factors such as insufficient preparation, incorrect methodology, unsuitable materials, and even a lack of verification during the earthworks process. Here’s a brief look at the most common causes of soil compaction that you should be aware of.
Moisture Content is Incorrect
The number one factor that contributes to compaction failure stems from incorrect moisture content levels in the soil. This usually means that the soil is too wet or excessively dry and, as a result, can not be compacted correctly.
For the most part, soil that’s too dry cannot bond as effectively as desired and ends up creating loose, brittle layers that will eventually crumble. Overly wet soil, on the other hand, ends up being too soft and unstable. When this happens, it’s almost impossible to achieve the necessary densification.
Keep in mind that poor drainage and water control before, during, and after the initial compaction will significantly undermine the intended soil strength. Typical signs of drainage-related issues often include the following:
- Seepage from adjacent areas
- Water pooling on or around compacted surfaces
- Uncontrolled stormwater flow
Your engineering team needs to ensure proper drainage management. Not doing so will see even the most strongly compacted soil losing its initial strength if it’s exposed to too much water.
Creating Layers that Are too Thick
Not all issues related to compaction failure stem from issues with the soil itself. Some are as a result of the way the soil layers are created in the compaction process. To achieve effective compaction, the layers, or lifts, are placed one on top of the other (referred to as a fill).
When a fill is placed too thickly, the following issues can arise:
- Lower layers remain loose and don’t compact
- Compaction energy doesn’t penetrate the full stack of layers
- Density tests provide inconsistent or failed results
In this instance, it’s essential to point out that even using soil or fill of the highest (and most stable) quality will be at risk of compaction failure if the layer thickness isn’t done according to regulated specifications.
Not Preparing the Subgrade Correctly
The first step in the compaction process is usually to ensure that the correct subgrade is used. This refers to the quality of the underlying soil, which means that if the ground is contaminated, wet, too soft, or uneven, it will negatively affect the lift.
Essentially, this means that you won’t be able to build strong and durable layers on soil that’s too soft or uneven. Effective soil testing will highlight these issues, and your engineering team is then responsible for stabilising the inferior subgrade. Corrective measures such as these will then result in more effective, long-term soil settlement, reducing the risk of compaction failure.
Final Thoughts
The number one way to avoid soil compaction on your building site is to enlist the services of a specialised geotechnical engineering company. This ensures that professional testing is done according to all necessary legislation and also that the necessary supervision is adhered to. Doing this will go a long way towards giving you peace of mind that your foundation is as strong as it needs to be, ensuring long-term durability!