Reasons Why Geotechnical Testing is Crucial for Construction
In construction, what you don’t know can cost you.
You can have world-class designs, top-tier materials, and flawless execution—but if the ground beneath your project can’t support it, it could all come crashing down. Literally.
That’s where geotechnical testing comes in. This is more than just a box to check off; it’s the foundation—pun intended—of any safe, cost-effective, and long-lasting project. Without it, you're gambling with your structure, your budget, and in worst-case scenarios, lives.
Let’s dig into why geotechnical testing is non-negotiable and how it helps uncover the unseen forces at play beneath the surface.
Getting to Know the Ground: How Soil Properties Are Determined
No two sites are alike. Each one comes with its own unique mix of soil types, rock layers, moisture content, and subsurface quirks. Geotechnical testing helps uncover these hidden details through a variety of investigative methods:
Standard Penetration Testing (SPT): Measures soil density and strength by driving a sampler into the ground—vital for understanding bearing capacity.
Cone Penetration Testing (CPT): Pushes a cone-shaped probe into the soil to gather data on layering, shear strength, and pore water pressure—ideal for layered or soft soils.
Laboratory Analysis: Soil samples are tested for properties like grain size, plasticity, moisture content, and compressibility—factors that heavily influence settlement potential and structural stability.
These tests reveal whether the soil can hold the load—or whether you’ll need to modify your design or improve the ground conditions with methods like preloading, soil replacement, or deep foundations.
The Price of Neglect: What Happens When Geotechnical Testing Is Overlooked
Let’s look at three real-world examples where the consequences of skipping or undervaluing geotechnical analysis were dramatic—and how these failures could have been prevented.
The Leaning Tower of Pisa:
Built in the 12th century on a foundation of soft clay, sand, and shells, the Leaning Tower of Pisa began tilting before construction was even finished. Without geotechnical testing (which didn’t exist at the time), the builders had no way of knowing that the soil beneath one side was significantly weaker, leading to centuries of structural instability.
How testing could have helped: Even basic modern soil tests would have revealed uneven compressibility. Engineers today would use soil stabilization techniques, design a deeper or compensated foundation, or choose a more stable site altogether.
Morandi Bridge Collapse (Genoa, Italy, 2018):
The collapse of the Morandi Bridge resulted in 43 fatalities. While corrosion and maintenance issues were front and center, investigations also revealed a lack of rigorous geotechnical assessment during both the original design and later retrofits. The bridge’s piers rested on foundations that hadn’t been adequately assessed for long-term soil-structure interaction or groundwater dynamics.
How testing could have helped: Modern geotechnical monitoring could have identified differential settlement, weakening soil, or groundwater-related erosion beneath the piers—issues that advanced sensors and site-specific testing now routinely catch. Proper evaluation might have triggered foundation reinforcement or even full structural redesign.
Dyck Memorial Bridge Collapse (Saskatchewan, 2018):
Just hours after it opened, this rural bridge collapsed. Investigations revealed the foundation design was based on generic soil assumptions, not site-specific data. The soil had insufficient bearing capacity for the structure, which led to a dramatic and sudden failure.
How testing could have helped: A site-specific geotechnical investigation would have identified the weak, compressible soils and prompted a redesign—possibly switching to deep foundations, soil replacement, or preloading. This case underscores the regulatory and professional responsibility for geotechnical due diligence in Canada.
Beyond the Basics: Unconventional Investigation & Monitoring Methods
Geotechnical testing isn’t stuck in the past. Engineers now have access to powerful, non-intrusive methods that deliver real-time data and deeper insights than ever before.
Geophysical Techniques (like Ground-Penetrating Radar and Electrical Resistivity Imaging): These methods allow engineers to visualize subsurface conditions without digging, making it easier to locate buried materials, water tables, or changes in soil density.
Electrical Resistivity Tomography showed three distinct strata that corresponded well to the test pits and boreholes. High resistivity (red/orange in images) indicates dry sandy gravel with high cobble/boulder content. Medium resistivity (green-yellow) indicates damp sandy gravel with a higher silt content. Low resistivity (blue) indicates compact, moist and silty lodgement till.
Real-Time Instrumentation: Tools like piezometers, inclinometers, and settlement plates track how soil behaves over time and under load—especially useful during construction to catch shifts before they become disasters. These techniques have been used for centuries but equipping these with cloud based real time monitoring and data collection allows for engineers to provide real time recommendations and suggestions.
Sustainable Ground Improvements: Techniques like lime/cement stabilization and the use of geosynthetics help enhance soil performance while lowering environmental impact. As movement of excess soils in many Canadian regions start to become more stringent, these older techniques seem more appropriate and therefore are gaining more traction and refinement of the application of these technologies.
Together, these methods help ensure that construction is not only safe but efficient and environmentally responsible.
Forecasting Slope Failure: Predicting Collapse Before It Happens
This is where geotechnical testing gets innovative.
Research out of China, led by Xu et al. (2011), has given engineers a powerful new tool: the ability to predict slope failures hours—even days—in advance, using advanced displacement-time modelling.
Their method identifies a three-phase deformation process that all creep slopes go through:
Primary Creep – Slow, decelerating movement.
Secondary Creep – Steady-state, often deceptive stability.
Tertiary Creep – Accelerating deformation leading to collapse.
The key? Monitoring acceleration and tangential angles of slope movement. Once slopes move into the tertiary phase, acceleration spikes dramatically. By identifying these patterns and setting alert thresholds (like 0.5 mm/day² in some cases), engineers can issue warnings up to 10 hours in advance of failure.
This technique is already saving lives. In the Baishi landslide case, warnings were issued days before collapse thanks to real-time monitoring and this predictive method. People were evacuated, infrastructure was protected, and a major disaster was averted.
This isn’t science fiction—it’s the new frontier of geotechnical safety.
Frost heave occurs when the following three conditions are met:
Regulatory Compliance and Canadian Relevance
In Canada, geotechnical testing plays a central role in meeting building codes and environmental regulations. Whether you're managing frost-susceptible soils in Ontario or landslide-prone slopes in BC, comprehensive soil analysis is often required by permitting authorities.
Projects that skip or rush this process risk delays, fines, redesigns, or worse—total failure.
Final Thoughts: Build With What You Know
You wouldn’t build a structure blindfolded—so why build on unknown ground?
Geotechnical testing provides clarity, security, and data-driven decisions from day one. It protects your investment, safeguards people, and ensures compliance across every level of the project lifecycle.
At PRI Engineering, we bring the science of soil to the forefront of construction. With expert analysis, innovative tools, and decades of experience, we help you de-risk your project and build with confidence. Have a project in mind? Let’s make sure your foundation—both literally and figuratively—is rock solid.