Geotechnical Risk Management for High-Rise Developments

Introduction: why geotechnical risk defines high-rise success

High-rise construction places exceptional demands on ground conditions. Tall structures concentrate loads, require deep foundations and often involve multi-level basements extending well below natural groundwater levels. In dense urban environments, these works are typically undertaken immediately adjacent to existing buildings, infrastructure and buried services.

From our experience on complex developments, high-rise geotechnical risk is rarely about a single failure mechanism. It is more often driven by uncertainty: incomplete ground models, underestimated settlement, unanticipated groundwater behaviour, or risks identified too late to be managed cost-effectively. Effective geotechnical risk management therefore begins well before excavation starts, through early investigation, integrated design thinking and a clear understanding of how ground behaviour interacts with construction sequencing.

Deep basement risks in tower developments

Deep basements are a defining feature of modern tower developments and one of the highest geotechnical risk elements. Excavations at depth interact with variable ground conditions and groundwater regimes that are not always apparent from shallow investigations.

A deep basement geotechnical investigation must extend beyond confirming founding strata. It should characterise soil and rock conditions at depth, understand variability across the site, assess strength and compressibility, and identify groundwater levels, pressures and seasonal behaviour. Where investigations are insufficient, construction-stage surprises such as weaker layers or unexpected groundwater inflows are more likely.

Excavation support systems, including diaphragm walls, secant piles and anchors, introduce further risk if design assumptions do not reflect actual ground conditions or construction sequencing. Underestimating these factors can result in wall movement, ground loss and increased excavation settlement risk beyond predicted limits.

Interaction with neighbouring assets

Most high-rise sites are constrained by surrounding development. Even relatively small ground movements associated with deep excavation can cause differential settlement, cracking or service disruption to neighbouring properties. These impacts are a common source of claims and disputes, particularly where adjacent structures are sensitive or heritage-listed. Early identification of these risks is essential to inform both design and construction controls.

Settlement and groundwater: coupled risks

Settlement and groundwater behaviour are closely linked in tower developments and must be managed together. Settlement may result from excavation-induced stress changes, consolidation under new loads, ground loss behind retaining systems or changes in groundwater regime.

Deep basements frequently require groundwater control, which introduces additional risk. Excessive drawdown can extend settlement impacts beyond the site boundary, create uplift pressures on basement slabs or lead to seepage-related instability. Groundwater-related settlement is one of the most common drivers of off-site impact claims.

Monitoring plays an important role in managing these risks, but it is not a substitute for good design. Instrumentation helps confirm assumptions and trigger responses, but if risks are underestimated at the design stage, monitoring alone cannot prevent damage.

Design-stage mitigation: where most risk is managed

The most effective opportunity to manage high-rise construction geotechnical risk is during design, when options remain flexible. A robust ground model that reflects variability and credible worst-case scenarios underpins foundation design, excavation support systems and construction sequencing.

Foundation and basement designs should be tailored to site-specific risks, including load transfer mechanisms, settlement tolerance of the structure and neighbouring assets, groundwater pressures and constructability constraints. Decisions made early can significantly reduce long-term settlement and groundwater risks.

Geotechnical risk is also influenced by how the project is built. Design-stage mitigation should consider excavation staging, groundwater management approaches and alignment between design assumptions and contractor methodology. Clear alignment between design intent and construction practice is critical to avoiding unintended ground behaviour.

Common geotechnical risk pitfalls

Across Australian high-rise projects, recurring issues include investigations that do not extend to ultimate basement depth, groundwater risks addressed too late, settlement criteria that are not aligned with adjacent asset sensitivity, and weak linkage between geotechnical design and construction sequencing. These issues increase both technical and commercial risk.

Conclusion: geotechnical risk management is a value driver

Geotechnical risk management is not simply about avoiding failure. For high-rise developments, it underpins programme certainty, cost control and stakeholder confidence. By investing in appropriate investigation, understanding deep basement and groundwater risks, and embedding mitigation at the design stage, project teams can significantly reduce exposure to settlement, delay and dispute.

At Nova Group Pacific, we support developers and project teams to identify and manage tower development ground risk as part of an integrated environmental and risk management approach. If your project involves deep basements or challenging ground conditions, early geotechnical risk planning can make a critical difference.

Contact our team to discuss geotechnical risk strategies for your high-rise development.

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