Along with these key milestones, SB3 has delivered several other assets on its N1/N2 contract this year: the Cromwell Lane Bridge Diversion, Curzon 3 Viaduct, Duddeston Mill Road Underbridge, Lawley Middleway Viaduct and the M42/M6 Link. The team has also completed two assets for the M6 South Viaduct, four assets for the Streethay Cutting Retaining Structure and Phase 2 of the Attleboro Lane Overbridge.
In addition to this, the JV is progressing well with its rigid inclusions work, having recently completed the Mercote Mill Lane Embankment site – this saw the installation of 327 rigid inclusions and two O-Cell piles.
Investing in sustainable plant
During the delivery of the N1/N2 contract, SB3 has continued to support HS2’s environmental commitment. So far in 2023, the JV has trialled a range of the industry’s latest cleanest low-carbon equipment, including electric rigs, fuel efficient plant and tracked concrete pumps.
Earlier this year on the Burton Green Retaining Structure, SB3 installed over 1,000 secant piles using just one rig – despite the original requirement for three conventional rotary bored piling rigs.
At the Curdworth North asset, the JV used the Bauer eBG33 electric rig for four months of the programme. By opting for the eBG33 instead of a traditional diesel-powered rig, SB3 significantly reduced emissions and noise pollution.
Other plant that has been piloted on the project recently includes the new Casagrande B175 piling rig. Compared to older models, this rig offers increased efficiency thanks to a Smart Power Management (SPM) system. Moreover, it benefits from greatly reduced noise emissions as a result of sound-absorbing materials and oil heat exchangers.
In addition to this, SB3 has invested in a modern, compact Hydrofraise®, which is more fuel efficient, consuming less diesel than traditional models. The JV has also procured tracked concrete pumps for use across its sites, which consist of just a single length of hose with no intermediate section. The concrete pump set up requires no cranes or concrete agitator, which is increasing productivity and reducing health and safety risks.
Adopting an innovative approach
Alongside these environmental achievements, SB3 has been responsible for several valuable geotechnical innovations. While working on HS2’s Streethay site, SB3 designed and fabricated a ring-shaped frame to support the tremie hopper during the removal of temporary casing from a bearing pile. The frame allows the tremie hopper to be easily detached and reattached to the lifting equipment. The innovation provides a safer and more efficient method than the traditional technique of suspending the hopper from a Kelly bar. Due to its success, SB3 has adopted the solution for all piles installed on the M42/M6 site.
During the delivery of rigid inclusions, SB3 designed a plunger tool to help install CFA reinforcement cages and central steel bars to the correct level. This innovation has been successfully deployed across all rigid inclusion sites on the N1/N2 contract. The plunger works by controlling the position of the reinforcement in the pile. Therefore, the tool provides increased accuracy and efficiency as it removes the need for operatives to manually control the position of the reinforcement.
Another creative solution implemented by SB3 was the use of the cutting-edge O-Cell (Osterberg Cell) technique to carry out pile tests on the Water Orton site. An O-Cell is a hydraulically driven, calibrated, sacrificial jacking device installed within a pile to enable full scale static load testing. The team chose to use O-Cells due to insufficient space for anchor piles. Unlike other static load testing methods, the O-Cell requires a much smaller working area and is capable of testing high-capacity, large diameter bored piles.