You don’t necessarily need to be an expert on mini piling to know that selecting the right type of piling is one of the single most critical decisions in a project to ensure the stability and longevity of a structure. Now, there are a variety of options for contractors to choose from, depending on what best suits the specific requirements of the project.
Here at Vxcel, we often work on projects that call for friction piles and drop rating piles. Both of these deep foundation systems are widely used within the industry, and each is designed to address specific soil conditions and load requirements. If you’re a private homeowner (or even a commercial customer, such as a property developer), you typically won’t need to be completely familiar with all the in-depth technical details on each one, so we’ll spare you an exhaustive post. Instead, we’ll just take a quick look at the key characteristics of each one, and the guidance on when to use each type.
What are friction piles?
Friction piles are the go-to choice of piles for us here at Vxcel. These are deep foundation elements designed to transfer load to the soil, mainly through friction. These slender columns are typically driven deep into the ground until they reach a depth where the surrounding soil can provide adequate resistance. In other words, they’re pushed down until they can’t go any further.
The slightly more scientific way to say this is that the load-bearing capacity of friction piles relies on the frictional resistance generated between the surface of the pile and the soil it penetrates. This makes them particularly effective in cohesive soils like clay, as well as granular soils like sand.
One of the main advantages of friction piles is they’re capable of supporting significant loads without requiring extensive excavation or ground improvement. They’re especially useful in areas where traditional shallow foundations may fail due to inadequate bearing capacity. What’s more, friction piles can be installed in restricted spaces, making them useful for mini piling. Indeed, they’re often used in urban environments where space is limited.
The flipside is that they may not be quite as effective in loose or poorly compacted soils, where the friction may not develop sufficiently. This can potentially lead to settlement issues over time, such as subsidence.
What are drop rating piles?
Drop rating piles, also known as end-bearing piles, are designed to transfer loads mainly through the pile tip resting on a strong, stable layer of soil or rock. These piles are driven deep into the ground until they reach a solid bearing stratum capable of supporting the weight of the structure above. This makes them particularly effective in sites where strong underlying layers are present, such as bedrock or dense gravel.
The key characteristics of drop rating piles include their ability to support heavy loads through direct contact with a firm foundation layer. This makes them an excellent choice for high-rise buildings and heavy structures that require reliable load-bearing capacity.
Equally, two of the main advantages of drop rating piles are their high load capacity, as well as their relative ease of installation in suitable soil conditions. However, they’re sometimes less viable in areas where the solid bearing layer is not as easily accessible, or where soil conditions may change unpredictably.
Key differences between friction piles and drop rating piles
As you’ve probably inferred, the primary difference between friction piles and drop rating piles lies in their mechanism of load transfer. Friction piles rely on the frictional resistance between the pile surface and the surrounding soil to support loads, whereas drop rating piles transfer loads directly through their tips to a solid bearing layer below. This fundamental difference affects their applications and suitability, based on the soil conditions on the job in question.
Friction piles are best suited for softer soils where friction can develop effectively, while drop rating piles are ideal for scenarios where a solid bearing stratum is available. The installation methods are different too; friction piles are often installed using a driving technique that allows for penetration into cohesive soils, while drop rating piles may require more robust equipment to penetrate harder layers effectively.
When to use friction piles or drop rating piles
The choice between friction piles and drop rating piles is one that needs to be made based on several factors, including soil conditions, load requirements, and site constraints. Friction piles may be the better option in situations where the soil consists of softer, less stable materials, as they can effectively utilise friction to support the structure. On the other hand, if a solid layer is present at a reasonable depth, drop rating piles may provide a more reliable and higher load capacity.
The type of structure being built also matters. For high-rise buildings or heavy industrial facilities, drop rating piles may be more suitable due to their ability to handle significant loads. On the other hand, for residential buildings or structures in urban environments where space is constrained, friction piles may offer a more practical and efficient solution.
Ultimately, if you’re not entirely sure which option is best for your project, don’t worry – that’s what our team is here for at Vxcel Piling. As highly experienced mini piling contractors, we have well over a decade of delivering exceptional results – encompassing domestic projects, commercial properties, and industrial warehouses. That gives us all the experience we need to assist you in as much or as little depth as you need. To find out what we’ve achieved for previous customers, feel free to take a look through our case studies!