Screw piles or helical piles are steel structures used to anchor foundations properly. They are especially useful for deep foundations, and present a host of benefits over other types of foundation anchors. Screw piles are a cost-effective foundation option for high-risk construction grounds such as areas with high water-tables, marshy soils, contaminated soils and sites with restricted access. Below are some advantages of screw piles in detail:
Screw piles are more easily installed compared with auger cast piles, driven piles and drilled piles, since they utilize less specialized, lighter and smaller installation equipment than the above. Within just a few hours, you can install all the screw piles for a small building. In addition, for limited-access sites like within existing buildings, screw piles can be installed using hand-held equipment.
Large carrying capacity
Unlike conventional piles, whose capacity is determined both by the pile-tip's end bearing and the skin friction produced on the pile-shaft's vertical sides once installed in the ground, screw piles have their capacity determined only by the helical plate projection's flat contact area within surrounding soils. This gives the latter larger load-bearing capacity than conventional piles of similar length. Bolting multiple pile sections and screwing them into the ground can result in even greater carrying capacity.
Suitable for varying soil conditions
Screw piles can be successfully installed in many soil conditions, with competent bedrock, and gravelly or rocky soils being the few exceptions. The piles produce effective in-ground performance with high-risk soils such as earthquake zones where soils have potential for liquefaction, groundwater and caving soils. This is because helical piles have unique resistance to expansive soils and frost heave. They have thin central shafts that limit upward stress from soils heaves, with the helical plate projections resisting uplifts from expansive or frost-susceptible soils.
Less vibration on installation
Installing helical piles causes practically no vibration, which is extremely crucial when piles need to be installed around sensitive utilities or close to existing structures. Every single pile has a helical plate whose pitch is exactly similar to the others, minimizing the level of soil disturbance compared with other piling techniques like rotary bored or CFA.
Eco-friendly and sustainable
Building foundations using screw piles is a simple process of screwing the piles into the ground. This creates less soil displacement, so that there isn't excess soil that must be carried way from the site unlike poured-concrete foundations. In addition, installation of screw piles foundations require fewer truck trips from and to the construction site. This method does not create spoils which need appropriate disposal, unlike other deep foundation systems. As a result, you will not only reduce transportation costs, but also lessen the carbon footprint of the project in its entirety.
Screw piles are ideal for sites that require minimal environmental disturbance, such as construction of temporary foundations/construction around eco-sensitive sites. Once they are taken down they can be used for other projects.