Deep Foundation Systems

44 Million Pounds above, Innovation below How Malcolm Drilling made the Climate Pledge Arena Possible. The redevelopment of Seattle’s Climate Pledge Arena (formerly KeyArena) required one of the most complex foundation scopes in recent U.S. sports facility history.   With the historic, 44-million-lb roof preserved in place, Malcolm Drilling was tasked with executing the deep foundation and earth retention systems that made this landmark project possible.   - Temporary Roof Support Installation of 82 temporary drilled shafts, each carefully designed to transfer vertical loads from the iconic roof into competent bearing strata during the full excavation sequence. These shafts acted as the backbone of the temporary shoring system, ensuring stability while over 680,000 cubic yards of soil were removed beneath.   - Permanent Foundations Once excavation reached final grade (70 ft below existing grade), Malcolm constructed 117 permanent drilled shafts to carry the new arena’s vertical and lateral loads. Shaft diameters were optimized for both load capacity and seismic performance in challenging glacial soils typical of the Seattle basin.   - Excavation Support System To facilitate a safe and controlled dig, Malcolm engineered and installed a soldier pile and tieback shoring system covering nearly 178,000 square feet of perimeter wall. Multiple tieback rows were drilled and stressed to manage lateral earth pressures, while shotcrete lagging provided a continuous face.   - Groundwater Control The team deployed a series of eductor wells to mitigate groundwater inflows at the adjacent truck tunnel portal. This dewatering system was critical to maintaining stability of the excavation and ensuring dry working conditions during below-grade construction.   Malcolm’s scope exemplifies the value of integrated specialty contracting in deep foundation work.   Precision drilling in tight urban confines, risk management under an existing historic superstructure, and seamless coordination with structural engineers and the GC.   The project is a testament to how advanced deep foundation techniques can enable transformative redevelopment while preserving architectural heritage.

🔻 When Deep Foundations Become the Silent Heroes A few days ago in Bangkok, a dramatic ground collapse occurred due to massive leakage from underground sewer pipelines. The soil underneath an active building literally washed away within hours. Standing in front of this scene, one question comes to mind: Why didn’t the whole building collapse? The answer lies beneath the surface — in the deep concrete piles. Even though some piles cracked under unexpected tensile stresses and soil loss, the majority continued to carry the structure’s weight through end bearing and skin friction. They acted as anchors, resisting settlement and holding the building above ground despite the voids opening below. Now imagine this same building resting on shallow foundations only: the entire superstructure would have sunk into the collapse zone almost instantly. This case is a powerful reminder for us as geotechnical engineers: In flood-prone or water-sensitive areas, piles are not optional — they are essential. Proper pile design must account for tension resistance, load redistribution, and long-term soil–structure interaction. What looks like “overdesign” on paper often becomes the only safeguard against catastrophic failures. At the end of the day, piles don’t just carry loads — they carry safety, resilience, and trust in our built environment. #GeotechnicalEngineering #DeepFoundations #Piles #CivilEngineering #SoilMechanics #FoundationDesign #StructuralSafety #InfrastructureResilience #EngineeringLessons #FloodResilience

How we built over a live sewer for the extension element for our CIAT Awards shortlisted project.    Building over a sewer can be risky. The weight of a new structure can crush the pipe, leading to serious damage and costly repairs from the local water authority. To avoid this, we had to get creative. 💡    This sort of work is controlled under the Building Regulations and building over an existing sewer is only allowed if the building work 'is constructed or carried out in a manner which will not overload or otherwise cause damage to the drain, sewer or disposal main either during or after construction.'   First, I mapped out the existing drains and manholes to understand the depth and size of the pipes. We discovered they were over 2 metres deep, which meant we needed a specialised foundation system to bypass them.    After considering several options, I decided on piled foundations. This method uses deep "stilts" to transfer the building's weight well below the sewer pipe, ensuring no pressure is placed on it. This not only dealt with the risk to the sewer but also proved to be a safer, faster, and more cost-effective solution than the alternative which was 3m deep trench foundations.    The choice of roof structure also had an impact on the piled foundations and how they interacted with the sewer pipe. I proposed a cut timber roof supported off a steel ridge beam. This roof structure was designed to move loads to the long gable side wall of the extension [running parallel to the pipe] so the two short walls [on top of the pipe] were not as heavily loaded, this therefore reduced the loads above the sewer and the risk of the sewer being damaged. If trussed rafters had been used the loads would have been moved to the short walls thus increasing the loads on the existing sewers below. This detail was key to protecting the underground infrastructure.    To make this project even more interesting the piling sub-contractors who had been quite helpful pre-construction decided to change their T&C’s a week before installation. The Clients weren’t really happy with this late change so I helped source alternative piling sub-contractors at short notice who managed to turn things around in enough time. Was slightly stressful for a couple of weeks but we just about made it without any delay or cost changes.    We also had CCTV surveys completed before + during + after the building work to check the condition of the drains. This helped us identify if the drains were in good condition or if they had become damaged during the building work and needed some remedial repairs.    So, that’s how we successfully built over a live sewer.    I can’t stress how important the initial survey work is before design work is started, as this vital information will inform the initial and final design.    Wish me luck for the actual Chartered Institute of Architectural Technologists (CIAT) Awards event tomorrow in London, I’ll keep you posted! 😎

“The construction of the Burj Khalifa’s basement involved advanced deep piling techniques to ensure the stability of the world's tallest skyscraper. These deep piles were meticulously designed and installed to support the immense load of the building and withstand environmental stresses such as heavy winds and potential overloads. This foundational approach ensures long-term stability and safety, preventing any risk of structural failure due to these factors.” Certainly! Here’s a more detailed explanation of the real-world techniques and considerations involved in the basement construction of the Burj Khalifa: 1. Site Preparation and Excavation Geotechnical Analysis: Detailed geotechnical surveys provided crucial data about the soil composition, groundwater levels, and bedrock depth. This information was essential for designing the foundation system. Massive Excavation: Excavating the site involved removing approximately 60,000 cubic meters of earth. The excavation extended down to the bedrock, creating a large and deep pit. 2. Secant Pile Wall Construction: To support the excavation and prevent soil collapse, a secant pile wall was installed. This method involves drilling overlapping concrete piles into the ground, creating a solid barrier around the excavation site. Purpose: The secant pile wall helped to retain the surrounding earth and control groundwater ingress during construction. 3. Deep Pile Foundations Pile Design: The foundation utilized a combination of bored piles and a raft foundation. Bored piles, ranging from 1.5 to 2 meters in diameter and extending up to 50 meters deep, were drilled into the bedrock to anchor the building. Raft Foundation: Above the piles, a massive reinforced concrete raft, approximately 3.7 meters thick, was constructed. This raft distributes the building’s load evenly across the piles. 4. Reinforcement and Concrete Reinforcement: High-strength steel rebar was used extensively to reinforce the concrete, ensuring structural integrity under the immense load of the Burj Khalifa. Concrete Quality: High-strength concrete was used to withstand the significant forces applied by the building and the environmental conditions. 5. Waterproofing Membranes and Coatings: Advanced waterproofing membranes and coatings were applied to protect the basement from groundwater infiltration. This was crucial given the high water table in Dubai. Drainage Systems: A comprehensive drainage system was installed to manage any water that might seep into the basement, further safeguarding the structure. #BurjKhalifa #DeepPiling #FoundationEngineering #SkyscraperConstruction #StructuralStability #HighRiseBuilding #AdvancedEngineering #BuildingTheFuture #ConstructionInnovation #MegaStructures

🔍 Foundation Types Explained – Selecting the Right System Foundations are essential for transferring structural loads safely to the ground. The selection of the appropriate system depends on soil conditions, load requirements, and project constraints. Below is a clear overview of common foundation types: 1. Isolated Footing A shallow foundation consisting of a reinforced concrete pad supporting a single column. ✔ Cost-effective and simple to construct ✔ Suitable for low to moderate loads ✖ Not recommended for weak or compressible soils 2. Steel Tube Pile A steel casing driven into the ground, often filled with concrete and reinforcement. ✔ High load capacity with both end bearing and skin friction ✔ Ideal for deep foundations and harsh environments ✖ Requires specialized equipment and higher cost 3. Precast Concrete Pile Factory-produced reinforced concrete piles installed by driving into the soil. ✔ High quality control and fast installation ✔ Suitable for heavy structures ✖ Transportation and handling can be challenging 4. Franki Pile (Bulb Pile) A cast-in-situ pile with an enlarged base to improve performance. ✔ Increased load capacity and reduced settlement ✔ Effective in weak soils ✖ Requires skilled execution and longer installation time 5. CFA Pile (Continuous Flight Auger) Constructed by drilling and pouring concrete simultaneously during auger withdrawal. ✔ Low vibration and noise — ideal for urban areas ✔ Fast and efficient installation ✖ Requires strict quality control and specialized equipment 📌 Key Takeaways • Foundation selection primarily depends on soil bearing capacity and structural loads. • Shallow foundations are suitable for strong near-surface soils. • Deep foundations are essential when surface soils are weak or loads are high. • Proper design and execution are critical to ensure long-term performance. 💡 Engineering Insight: There is no “one-size-fits-all” foundation system — the optimal choice balances safety, cost, and constructability based on project conditions.

Prestressed Diaphragm Walls – The Future of Deep Excavation Engineering Prestressed diaphragm walls combine the subtle brilliance of bridge prestressing techniques with the rigorous needs of deep foundation construction. Here’s why engineers are turning to this innovation—and where it makes the most impact. ⸻ What Are They? Prestressed diaphragm walls integrate prestressing tendons (steel strands or bars in ducts) into concrete panels. Once the concrete cures, the tendons are tensioned—applying compression to the wall. This counteracts tensile forces from soil pressure or excavation loads, improving structural resilience. ⸻ Why Use Them? • Efficient Material Use With prestressing, walls can be made thinner and lighter, reducing both steel reinforcement and concrete volume. • Enhanced Structural Capacity Compression imparted by tendons boosts bending strength and crack resistance—key for demanding loads. • Sustainability & Speed Less material and simpler logistics translate to lower costs and faster construction timelines. ⸻ Best Applications Prestressed diaphragm walls are particularly useful in: • Urban Deep Excavations Tight spaces benefit from thin-walled supports that maximize usable area. • Metro Stations & Underground Transport Hubs High load demands with minimal disruption makes this ideal. • High-Rise Basements Handling heavy earth and structural pressures with less bulk. • Marine & Waterfront Projects Durable against prolonged water exposure and high lateral loads. • Temporary Shoring Works Reusable tendon systems cut both time and cost for temporary structures. ⸻ How It’s Executed 1. Excavate Panel — Using trench cutters or grabs, panels are formed under slurry support. 2. Install Reinforcement & Tendon Ducts — Rebar cages and tendon conduits are positioned correctly. 3. Cast Concrete — Tremie method ensures proper filling and curing under slurry. 4. Insert & Tension Tendons — After strength gain, tendons are tensioned to apply compression. 5. Grout & Seal Ducts — Secures tendon and ensures long-term integrity. #CivilEngineering #DeepFoundations #PrestressedConcrete #InfrastructureInnovation #UrbanConstruction

Not all footers are created equal—and choosing the wrong one is where most failures begin. In masonry and concrete work, the footer (footing) is what transfers load to the soil. If that system isn’t right, everything above it is at risk—cracking, settlement, rotation, water intrusion. Here’s a breakdown of the most common types and why we use them: 🔹 Spread Footing (Continuous Footer) The most common in residential work. • Runs continuous under walls (foundation, retaining, steps) • Spreads load evenly across soil • Why: Simple, effective, and reliable when soil conditions are stable 🔹 Isolated (Pad) Footing Used under columns or point loads. • Square or rectangular pads • Supports concentrated loads (porch columns, piers) • Why: Handles heavy point loads without overbuilding the entire system 🔹 Trench Footing Concrete poured directly into a trench (sometimes with minimal formwork). • Often used in residential or light commercial • Why: Faster, cost-effective, and works well when soil is undisturbed and consistent 🔹 Stepped Footing Used on slopes or grade changes. • “Steps” down to maintain proper depth • Why: Keeps footer below frost line while following grade—critical for stability 🔹 Reinforced Footing Includes rebar (and sometimes fiber mesh) • Adds tensile strength to concrete • Why: Prevents cracking and increases structural integrity under load and movement 🔹 Frost-Protected Footing Designed to prevent movement from freeze/thaw • Deeper placement or insulation strategies • Why: In climates like Ohio, frost heave will destroy a shallow footer—this is non-negotiable 🔹 Pier / Deep Foundation (Helical, Sonotube, etc.) Used when surface soil isn’t adequate • Transfers load to deeper, stable soil layers • Why: When you can’t trust the topsoil, you go deeper—simple as that Bottom Line: Every footer is an engineering decision—even on residential work. You don’t choose a footer based on “what we always do.” You choose it based on: • Load • Soil conditions • Water • Frost depth • Long-term performance That’s the difference between something that lasts 2 years… and something that lasts a lifetime. By Justin Curatola #CuratolaMasonry #TheCuratolaGroup #FootersMatter #FoundationFirst #MasonryScience #ConcreteWork #StructuralIntegrity #BuiltToLast #NoShortcuts #ConstructionKnowledge #SkilledTrades #OhioConstruction #EngineeringMindset

🚧 WHY DEEP FOUNDATIONS MATTER — AND WHY BUILDINGS FAIL WITHOUT THEM 🚧 Most structural failures don’t start above the ground. They start beneath it. This illustration perfectly captures a truth every architect, engineer, and developer must respect: A building is only as strong as the soil that carries it. In many locations, the top layers of soil—especially clay, silt, and loose fill—are unstable, compressible, and highly sensitive to moisture changes. When heavy structures are placed on shallow foundations in these conditions, the result is predictable: • Uneven settlement • Tilting and rotation • Cracking and structural instability • Costly repairs—or total failure On the right side of the image, however, the story is different. Deep foundations (piles or drilled shafts) transfer building loads far beneath weak soil layers, anchoring the structure into dense sand or bedrock, where the earth is firm, consistent, and reliable. This is why skyscrapers, bridges, towers, and large residential or commercial developments must rely on deep foundations— not for aesthetics, but for survival. **Good architecture is not just about design. It is about integrity, safety, and understanding the invisible forces beneath our feet.** Whether you’re building a home, planning a high-rise, or designing a modern cityscape, remember: **Strong buildings begin with strong foundations. And strong foundations begin with strong decisions.**

🔹 Massive Excavation — Foundation Preparation for a Skyscraper 🔹 Standing at the bottom of this excavation really puts the scale of modern foundation engineering into perspective. What you see here is part of the deep foundation preparation for a high-rise structure, a crucial stage where geotechnical precision meets structural design. ✅ Retaining System: The vertical elements forming the wall are bored piles or secant pile walls, designed to retain the surrounding soil and control groundwater during excavation. They act as a temporary or permanent retaining structure, ensuring lateral stability and minimizing ground movement that could affect adjacent structures. ✅ Excavation Depth: Excavations for skyscrapers often extend several meters below ground level, not just for the foundation but also for basements, parking, and service floors. The deeper the excavation, the greater the lateral earth pressure and groundwater control challenges. ✅ Foundation Type: Once the excavation reaches the design depth, raft foundations, pile caps, or combined pile-raft systems (CPRF) are constructed to safely transfer the immense loads from the superstructure to the subsoil. ✅ Geotechnical Considerations: • Soil type and strength parameters dictate excavation support design. • Continuous monitoring of wall displacement and groundwater pressure ensures safety. • Ground improvement or dewatering may be required depending on subsurface conditions. Modern foundation engineering is a perfect example of how geotechnical and structural disciplines integrate, translating soil behavior into safe, durable structures that touch the sky. #CivilEngineering #GeotechnicalEngineering #FoundationDesign #Excavation #SoilMechanics #StructuralEngineering #ConstructionEngineering #BuildingTheFuture

Deep Excavation with Multi-Level Strutting System — Urban Underground Construction This project stage illustrates a large rectangular deep excavation supported by a perimeter retaining wall system (likely diaphragm wall or secant pile wall) combined with multiple levels of internal steel struts. This approach is typically adopted when excavation depth and surrounding risk make open slopes or tiebacks impractical. Key technical elements visible: • Perimeter retaining walls acting as both temporary earth support and often part of the permanent structure • Multi-level steel struts transferring lateral earth and groundwater pressures across the excavation width • Waler beams distributing loads from the wall to the struts • Progressive staged excavation — struts installed level by level as depth increases • Base slab reinforcement in progress, preparing for bottom slab casting and structural closure • Waterproofing and drainage measures along wall faces • Controlled access systems and working platforms for safe installation and monitoring Why this system is used: • Suitable for dense urban zones where ground anchors are restricted • Minimizes ground movement and settlement risk to nearby buildings and roads • Provides predictable structural behavior under high lateral loads • Enables deep excavation with tight footprint constraints Critical engineering controls at this stage typically include: — Instrumentation and monitoring (wall deflection, strut loads, settlement points) — Sequenced excavation and bracing installation — Groundwater control and uplift checks — Strut preloading to reduce wall movement — Connection detailing between walers and struts — Base stability verification before slab casting This phase is where geotechnical design, temporary works engineering, and construction sequencing must align precisely — execution quality here directly governs safety and long-term performance of the underground structure. #DeepExcavation #GeotechnicalEngineering #TemporaryWorks #UrbanConstruction #RetainingWalls #StruttingSystem #UndergroundStructures #ConstructionEngineering