Secant Piles/D-Wall

We deliver shaft construction using secant pile and diaphragm wall techniques, providing robust, water-tight retaining solutions for shafts, basements and deep excavations in complex and constrained environments. These methods are particularly effective where ground and groundwater control, settlement management and asset protection are critical to successful delivery. With safety as one of our core values, all works are completed to a standard we are proud of, using robust and innovative solutions underpinned by engineering-led planning and rigorous quality assurance. Through close collaboration with our trusted specialist supply chain, we offer the capability to design and construct complex piled shaft solutions with confidence across a wide range of ground conditions and geometries.

Our secant piled shafts are constructed using rotary bored or Continuous Flight Auger (CFA) techniques, selected to suit ground conditions, pile diameter, depth and site constraints. These methods allow precise pile installation, controlled overlap and reliable cut-off, forming continuous retaining walls capable of resisting earth and groundwater pressures. Where appropriate, diaphragm walling is employed to deliver high-stiffness, low-permeability shaft walls for larger diameters, deeper excavations or particularly demanding groundwater regimes. Excavation within secant pile or diaphragm wall shafts is carefully sequenced, with temporary and/or permanent propping systems installed as excavation progresses. Propping arrangements are designed to manage wall deflections, maintain stability and protect adjacent assets, and may include internal steel frames, ring beams or slabs cast at intermediate levels. Where required, permanent structural elements are integrated into the temporary works strategy to optimise programme and reduce duplication.

Our integrated approach ensures seamless coordination between design, piling, excavation and propping activities. Early engagement with designers and stakeholders allows us to manage interfaces, programme constraints and risk from the outset, providing programme certainty and quality execution throughout delivery. Continuous monitoring and verification are applied to confirm performance against design assumptions and acceptance criteria. By combining specialist piling techniques, experienced delivery teams and collaborative supply chain partnerships, we deliver safe, precise and resilient secant piled and diaphragm wall shafts, capable of supporting complex underground works in the most challenging environments.