Specialist Screw Piling Contractors in Sussex
Screw Piles and Helical Anchors
Murray Andrews and its supply chain partners have mapped out the path and developed our own engineering design, procedures & methods. Our work and credentials stand for itself.
From working with engineers, architects, government agencies and contractors, we really get a keen sense for what makes people comfortable with the unknown. Let us do the worrying below ground so you can concentrate on the project above!
Incorporating the same work practices and effects from a simple house extension to our Special Projects division, which strives on giving solutions and solving the impossible in any environment across all sectors in the construction industry.
Using the latest innovations in project data recording our field crews can generate stage by stage, pile by pile data recordings while giving our clients the peace of mind that they have a true clear, accurate log of every pile location which has be installed.
Potential Advantages and Limitations of Screw-Piles and Helical Anchors:
Rapid Installation – there is no need for additional equipment, such as a crane with a pile hammer or a large drilled shaft rig. This makes for faster solution for our clients, Murray Andrews can respond and be on site quickly. Large load capacities can be obtained using relatively small installation equipment.
Screw-piles and helical anchors are usually installed using conventional construction equipment such as a track excavator or a mini-excavator equipped with an appropriately sized low speed high torque hydraulic motor.
Immediate Load Carrying Capability - Screw-piles and helical anchors are unique among most other types of foundations or anchoring systems in that they can be loaded immediately after installation. There is no need to wait for concrete or grout to harden, or in the case of driven piles, no need to wait for excess pore water pressures to dissipate. This can be important on some projects, for example emergency response where the construction schedule is short and the rest of the project depends on installation of the foundations or anchors. With no concrete involved in the process, screw piles can be loaded instantly and can be supplied with a variety of terminations to suit steel, aluminium, timber or concrete superstructures with the capabilities of supporting 250kN (25tonnes) per pile.
Minimal Site Disturbance – This gives our clients a more accurate reading of the Carbon footprint analysis, with added benefits in recording their waste management process data for the project.
Relative to most other types of construction activity involving the installation of driven piles, drilled shafts or other anchoring systems, the installation of screw- piles and helical anchors produces little to no disturbance of the site. Specifically, the installation of screw-piles and helical anchors typically produces no soil cuttings. This keeps the site clean, requires minimal clean up at each installation locations after installation, and usually means lower project costs. An additional advantage is the low noise level associated with installation.
Installation also produces minimal vibrations which can be important on some projects that are sensitive to construction vibrations. Since screw-piles and helical anchors have a small work footprint they also produce minimal disruption to adjacent structures. In cases of retrofitting or restoration, existing structures can often still be used while screw-piles or helical anchors are being installed. Since they produce no soil cuttings they can also be used efficiently at sites where contaminated soils may be encountered since the soils do not come to the ground surface.
Installation Monitoring and Verification of Load Capacity During Installation – One of the most important features of screw-piles and helical anchors is the verification of load capacity during installation. In some respects, this is similar to monitoring the installation of driven piles by using a Pile Driving Analyzer during installation. This is possible by using a direct in-line torque measuring device that measures the installation torque as the pile/anchor advances into the ground. Many studies have shown that there is a relationship between installation torque and load capacity, which means that engineers can verify capacity immediately. On most projects, this torque-to-capacity relationship is verified with on-site load tests. Monitoring the installation torque also means that the soil conditions at every installation location can be verified and the subsurface variability can be assessed. By monitoring installation torque, the required load capacity can be developed by going deeper into better soil or by using a different pile/anchor geometry. Installation torque is often used as part of the allowable termination criteria given in the project specifications.
One of our other unique features of screw-piles and helical anchors that makes them highly versatile is the ability to quickly modify the configuration of the helical elements to increase load capacity. This is achieved in part by the modular nature of the technology. Adding extension sections with additional helical plates and/or helical plates of larger diameter is easy and means that the engineer can quickly develop a solution without requiring the fabrication of an entirely new foundation or anchor. This again shows the versatility of the technology.
Easy Installation on any angle – while it’s common to install screw-piles and helical anchors vertically, in fact they can be installed at almost any orientation to suit the needs of a project. Installation on an angle, for example to provide additional resistance for lateral loading, is simple. For earth retaining projects, even the installation of helical anchors horizontally can be accomplished with no particular difficulty.
Low Carbon Footprint – Sustainable Technology - many manufacturers of screw-piles and helical anchors use high quality recycled steel to in their fabrication. This conserves natural resources and energy and reduces the overall carbon footprint. Screw-piles and helical anchors are especially useful for support of temporary structures since they can be removed and reused with little to no change in structural integrity. This is very different that a driven pile or drilled shaft or a grouted anchor which are often just abandoned. Some screw-piles have been in place for several years, have been removed and reused at another site.