New super heavy-duty shoring system deployed for complex basement excavation

Find out how the installation of Australia’s largest double-acting hydraulic ram kept excavation safe and on schedule for Empire Global

The project

Builder Empire Global Constructions is constructing the Emporium Apartments, a mixed-use development at 305 Anketell Street, Greenway, in the ACT. The eight-storey design features 146 new apartments and space for commercial leases on the ground floor. A two-level basement structure will house bicycle cages, and parking for up to 160 cars.

Although the initial shoring design specified the use of structural steel, this approach was hampered by the proximity of in-ground services and the inability to anchor below neighbouring properties. Empire also sought the assurance of a proven solution that was more cost-effective and readily available than steel, to minimise risk and ensure the safety and integrity of the excavation site.

“Having partnered previously with Empire to supply hire equipment, in 2022 Coates was invited to deliver an alternative internally braced solution using its proprietary hydraulic struts,” says Coates Temporary Works Engineer, Philip Lord. “This project also provided Coates with the opportunity to complete its first installation of the new super heavy-duty MP375, Australia’s largest double-acting hydraulic ram.”

The challenge

Empire faced some unique challenges in designing and installing a shoring solution to support this basement structure.

Inclement weather

Unseasonably wet weather caused some scheduling issues for the builder. “Weather delayed our start on site and has been a progressive issue ever since,” says Empire’s Construction Manager, Joe Tonkovic. “The stop-start rain, and the amount of groundwater and rock that we had to deal with as we excavated the basement, meant that we didn’t have the best start to this project. But these factors were out of our control, and once we reached the bottom, we were able to move forward smoothly.”

Connecting to the pile cap

Securing the struts to the piling presented some additional challenges early on. “Being able to use core drilling to connect the hydraulic system to the capping beam was a key part of the planned installation process, but before this could happen the piling contractor needed to perform some additional design adjustments and analysis,” says Phil. “Once we had approval, we were able to install the system without other issues or delays.”

As this was the very first application of the new MP375 strut, Coates also had to design and certify new custom end bearing plates to provide a secure connection.

Supporting high structural loads

Empire’s two-level basement excavation was subject to high structural loads, due to the proximity of a sewer line and two neighbouring properties. “We decided to introduce Coates’ new MP375 strut to provide maximum support, and to offer the client the assurance of a system that they knew would withstand these loads,” says Phil. “The super heavy-duty strut was ideal for this application, because of its capacity to support up to 375t, and for the large spans that it can cover.”

The solution

Working in conjunction with Empire and consulting engineers Indesco, Coates successfully designed and implemented a robust hydraulic shoring solution that safely braced the basement structure during excavation. This system included 3 hydraulic knee struts that were applied to the capping beam at various lengths and configurations, including an MP150 at 6.5m; an MP150 (at 17m long); and an MP375 (at 27.5m long) with Super Tube Extensions for increased load and spanning capacity.

Coates’ scope of works for this project included engineering and design services, plus the supply, transportation, installation, installation certification and removal of all shoring equipment.

The impact

Safety, availability, cost efficiency and customer service were standout features of the temporary works solution that Coates deployed.

Safety

Recent shoring collapses in the ACT have highlighted the need for the assurance of a safe working environment. According to Phil, Empire valued the safety of the Coates’ system, and managed to adapt excavation to accommodate this approach.

Cost and efficiency

Continuing global supply chain issues and the recent increase in the price of steel also made Coates’ system comparatively quick and cost-effective to design and install.

“Although this was the first application of the MP375 in Australia, we had this strut and others ready for hire,” says Phil. “So not only did Empire avoid having to wait and pay the high price of steel, but they were able to access our system quickly to keep construction moving.”

Customer service

Joe describes customer service as a defining feature of working with Coates. “Throughout this project we found Coates to be very approachable and understanding of our requirements. We also appreciated their ability to accommodate our lead time, so we could get the props in place as soon as possible and minimise the time that we lost during excavation,” he says. “With the B1 slab poured, the struts have now been safely removed, allowing construction work to continue as planned.”

Connect with Coates Engineering Solutions or email engineeringsolutions@coates.com.au to find out how Coates can improve the cost, safety and efficiency of your next temporary works