Why Soil Testing Should Be the First Step in Any Earthworks Project

Earthworks are a fundamental part of any construction project, forming the base upon which everything else is built. From roads and bridges to commercial buildings and residential developments, properly executed earthworks ensure structural stability and long-term performance. Unfortunately, a significant number of earthworks failures can be traced back to a single, preventable issue—insufficient or ignored soil testing.

Ignoring the nature and behavior of the soil beneath a construction site can lead to a cascade of problems: structural damage, safety hazards, financial loss, and even complete project failure. In many of these cases, proper soil testing, especially using methods like DPSH testing, could have identified potential risks and helped engineers make informed decisions from the outset.

What Causes Earthworks Failures?

Earthworks failures occur when the ground beneath a structure cannot support its load or behaves unpredictably due to environmental factors. Common causes include:

  • Poor soil compaction

  • Unexpected ground movement

  • Inadequate drainage

  • Presence of expansive or collapsible soils

  • High groundwater levels

  • Unstable fill materials

All of these issues can be identified and mitigated through comprehensive soil investigation and testing before construction begins.

Real-World Examples of Preventable Failures

1. Road Collapse Due to Uncompacted Fill

In one documented case, a newly constructed roadway collapsed shortly after opening to traffic. Investigations revealed that the fill material used during earthworks was not properly compacted, and the underlying soil was loose and inconsistent. Had DPSH testing been performed before and during the fill process, the inconsistencies in soil resistance and compaction quality would have been flagged, preventing the collapse and associated repair costs.

2. Residential Development with Cracking Foundations

In a suburban housing development, several homeowners reported severe foundation cracking within months of construction. Further geotechnical investigation found that the houses were built on a mixture of expansive clay and loose sand. These problematic soil types had not been identified before earthworks began. If DPSH testing had been conducted during the early planning stages, the soil’s low resistance and expansive nature would have been detected, allowing developers to adjust the foundation design or stabilize the soil beforehand.

3. Industrial Site Slippage on a Slope

An industrial warehouse built on a sloped site experienced partial ground slippage after heavy rainfall. The cause was traced to water-saturated soils with low shear strength beneath the surface. The slope had been cut and filled without thorough testing of soil layers at depth. Using DPSH testing would have revealed changes in soil strength with depth and identified the need for proper drainage and retaining structures before construction.

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The Importance of DPSH Testing

DPSH testing (Dynamic Probing Super Heavy testing) is an in-situ geotechnical testing method used to assess the resistance of soil to penetration. This technique involves driving a probe into the ground using a fixed energy hammer, and recording the number of blows required to penetrate set depths.

This information helps engineers:

  • Determine soil strength and density

  • Identify soft or loose soil layers

  • Map variations in subsurface conditions

  • Evaluate suitability for foundations and compaction

Unlike traditional borehole sampling, DPSH testing offers rapid, real-time insights and is especially useful in preliminary investigations or where a continuous soil profile is needed.

How Soil Testing Prevents Failure

Comprehensive soil testing—including DPSH testing—can significantly reduce the risk of earthworks failure by:

  • Ensuring Proper Design: Structural foundations can be adapted to match soil conditions, whether that means using deep foundations, improving compaction, or reinforcing the subgrade.

  • Improving Material Selection: Engineers can choose the right fill materials and compaction techniques based on actual soil performance data.

  • Enhancing Drainage Planning: Testing helps identify areas prone to water retention or saturation, allowing proper drainage and waterproofing systems to be installed.

  • Saving Time and Money: Catching soil issues early prevents costly design changes, construction delays, and post-build repairs.

Many high-profile earthworks failures could have been easily avoided with thorough soil testing before construction began. Testing the ground is not just a formality—it’s a critical step in understanding the site and planning for long-term success. Methods like DPSH testing provide valuable data about soil strength and behavior, helping project teams make informed, evidence-based decisions.

By incorporating soil testing as a standard part of every earthworks project, construction companies can protect their investments, ensure public safety, and deliver more durable, reliable infrastructure. It’s a small step that yields massive benefits—and one that no responsible builder should ever skip.