Guide to Understanding Pile Driving
Pile driving is designed to ensure the structural integrity of deep foundations and heavy load buildings or platforms. Creating a foundation with adequate support is extremely important for industrial facilities. Pile driving provides this support with a variety of methods, each designed to work in specific conditions and for specific purposes. What follows is a look at what piles are and how they work, they types of piles available, and other key factors.
How Piles Work
Most types of piles work on similar principals. The support column is constructed beforehand and then driven into the ground by heavy impact hammers. Typically friction with soil locks the piles in place. Some types of piles are cast, meaning a form base is driven into the ground and then filled with the appropriate cement mixture. There are also cases where the soil is completely excavated before casting a column, but these are less common. Additionally, plate driving can be used to retain soil and construct seawalls. In every case, the driving method should be specifically selected to minimize damage to the soil, foundation and nearby structures.
Types of Piles
Different structures and sites will have different needs. When it comes to deep foundations and heavy load bearing, optimizing the support structure is a huge part of maintaining safe conditions and minimizing cost. Here is an overview of some of the different types of piles available.
- Prestressed concrete piles – As the name suggests, these piles are made of concrete that is mixed to specific needs. The concrete used is designed to reduce cracking and improve structural integrity, especially in cases of high tension.
- Reinforced concrete piles – Rebar is used to add substantial strength to the concrete. This offers structural advantages similar to that of prestressed concrete, but the strength applies to load bearing more than tension.
- Timber or wood piles – Timber offers less structural strength than alternatives, but it has much lower associative costs. When conditions allow for it, timber piles are the most cost-effective on the list.
- Steel or H-piles – Steel piles offer the highest amount of strength. Typical design uses h-shaped steel beams to create the pile, lending to the name H-pile. In many cases steel pipe piles are used instead of the H-piles.
- Composite piles – Composite piles are the result of linking multiple piles together. They can be made out of different versions of the other piles, and when fastened together they often offer more strength than their individual components.
- Augercast piles – These are made by drilling a hollow-stemmed, continuous flight auger. When the precise depth is achieved, concrete is poured into the auger while it is slowly removed, creating the cast. The concrete can be reinforced as needed. These piles offer the least amount of disturbance to a site.
- Steel plate piles – These are large steel sheets that are driven into the soil and then locked together. Their primary function is to retain soil, to prevent landslides, limit erosion, protect excavation sites and build seawalls.
Because pile structure varies so wildly, properly testing them may involve a few different processes. Many cast type piles need to be tested before they are installed, as samples cannot safely be pulled from them after the cast. Many prebuilt piles can be tested before driving as well, but in most cases they can also be tested post-drive as well. Besides that, the conditions of the structure can also limit testing opportunities. STI Group thoroughly takes these different factors into consideration when testing and certifying the structural integrity of piles.
Determining the Right Pile
The first step in selecting the correct pile for a project is surveying the ground and understanding soil and other environmental conditions. Rocky conditions will require specifications to prevent sliding. Soil composition and density will be major factors in determining the best driving method. Even in the case of water based structures, the brininess of the water and condition of the sea, lake or river bed will limit which pile types can stay put and withstand erosion. STI Group is able to offer expert advice on which type of pile is best for a given project.