Understanding Geotechnical Reports & Site Investigations

A geotechnical report is essential for every construction project. The intricate geotechnical analysis behind a report determines whether a project is ultimately safe and stable. Without these reports, it’s difficult to be confident in the future of a construction project. An uncertain future is difficult to fund, so geotechnical engineering experts remove all doubt.

Geotechnical engineering and testing make investors, property owners and construction professionals confident in the ground beneath their feet. Let’s discuss the many facets of a geotechnical report and how it benefits a project’s finances, sustainability and safety.

What is a Geotechnical Report?

A geotechnical report assesses a construction site’s underground conditions. Geotechnical engineering professionals often prepare this report, performing a rock and soil investigation to determine whether a site is feasible for construction.

If a site is not ideal for construction, a geotechnical report may outline solutions for improving it.

Key Objectives of a Geotechnical Report

• Evaluate Soil & Rock Profile: A geotechnical engineer or geologist performs a site investigation, noting the forms of rock and soil beneath the surface. 
• Analyze Groundwater Conditions: A site’s water table level and how this level changes seasonally is critical information for a construction project.
• Note Potential Risks and Hazards: Geotechnical engineering and testing may reveal and reduce dangers like landslides, unstable soil and subsurface pollution. 
• Make Engineering Recommendations: Geotechnical analysis informs construction best practices and plans, such as how to construct a building’s foundation. Engineers will determine whether to employ ground improvement strategies based on a geotechnical report’s findings.

Who Prepares and Uses Geotechnical Reports?

A geotechnical report is typically prepared by a team of geotechnical engineers and geologists. These professionals often specialize in soil investigation and subsurface mechanics. Their geotechnical engineering insights and testing are used to build a report on the site’s material makeup, risks, opportunities and more.

The report is used by architects, contractors, engineers and government authorities. 

5 Key Stages in Preparing a Geotechnical Report

Preparing a geotechnical report is a thorough, highly scientific process. This process can be broken down into 5 stages. Let’s look at how each step is essential to a full site investigation.

1. Initial Site Assessment

A geotechnical engineering crew will thoroughly review a site’s history before heading into the field. Comparing a site’s previous conditions to its current conditions is critical to making a proper geotechnical report.

This preemptive geotechnical analysis is achieved by reviewing site maps, disaster reports and other relevant information.

2. Field Investigations

Once geotechnical engineering experts are on-site, they perform numerous tests and collect a wide array of data. Common field tests include boreholes and test pits. An advanced site investigation will include techniques like ground penetrating radar and electrical resistivity tomography.

Let’s take a closer look at these methods.

Ground Penetrating Radar (GPR)

Ground penetrating radar (GPR) is a non-invasive method for mapping soil layers and underground objects. GPR can detect a problematic shift in soil types or rock content. This method is especially useful when a site has never been mapped or is feared to be unstable. 

Electrical Resistivity Tomography (ERT)

Electrical resistivity tomography (ERT) collects soil and rock data by running an electrical current through the ground. ERT reveals a subsurface’s density, water content and manmade infrastructure. Sinkholes and other dangerous cavities can be discovered using ERT.

3. Laboratory Testing

Once a geotechnical engineering team is done in the field, they head to the lab. Extensive tests are performed to profile a site’s soil and rock content. These tests reveal grain sizes, compaction characteristics and the maximum force the subsurface can withstand. 

Laboratory findings are critical to a construction project, making or breaking a site’s future. This is why accurate assessments are so important. Misinterpreting data can lead engineers and contractors in the wrong direction.

4. Geotechnical Analysis & Interpretation

Context is everything. Collecting data is important, but this data needs to be properly interpreted and applied to be useful. A geotechnical engineering team will apply their findings to a greater whole, creating a clear picture of a site’s material makeup.

This clear picture is created through several models, simulations and tables.

5. Finalizing the Report 

Now, we assemble the geotechnical report that engineers, contractors and regulators use. This report must be detailed, clear and logical. A full geological analysis should be contained inside—no important information should be omitted.

This report determines a site’s future, which likely has millions of dollars hanging in the balance.

The Importance of Geotechnical Reports for Construction Projects

An accurate geotechnical report informs a construction project’s stakeholders of risks, opportunities and best practices for a particular site. Engineers and contractors use a report’s information to guarantee a building’s structural integrity and protect residents’ safety.

Foundation Design

A site’s soil and rock content informs the type of foundation that is constructed. Depending on a site’s geotechnical report, a shallow, deep or specially tailored foundation will be built. Building the wrong type of foundation can compromise a property’s safety and severely delay a project’s completion.

Slope Stability

Most sites aren’t flat, and some have sharper and more varied inclines than others. Special measures must be taken to ensure a project’s safety on slopes. A geotechnical report will inform engineers’ methods, especially for road construction and hillside projects. A site’s slope stability informs stormwater management practices for every construction project. 

Earthworks & Excavation

A geotechnical report offers guidelines and best practices for safe site excavation. The report’s breakdown of groundwater and soil layers will determine whether excavation could compromise a site’s stability and long-term safety.

Failed excavation can result in huge losses and project abandonment, making accurate geotechnical analysis an indispensable resource for contractors.

Ground Improvement Techniques

Site safety is paramount to any construction project. Findings from a geological report will inform engineers’ efforts to stabilize and strengthen a subsurface, helping it withstand the necessary force of a construction project. Engineers may use grouting and geosynthetics to achieve this.

Geotechnical Engineering Expertise and Sustainable Solutions With AQUALIS

Determining a site’s soil health and load-bearing capacity is the first step in any construction project. Without a comprehensive geotechnical report, engineers and contractors cannot safely proceed with their work. 

Safe practices aren’t just recommended—they’re required. AQUALIS’ geotechnical services will help you proceed with the utmost care. Our geotechnical reports are informed by state-of-the-art technology and the work of highly qualified engineers. 

Once we have conducted a proper site investigation, your stakeholders will have a clear picture of what they are investing in. This removes guesswork from your project, highlighting environmental, financial and safety risks. 

Our geotechnical engineering experts will help you understand a construction site’s true value and feasibility. Together, you and AQUALIS can guarantee safe, eco-friendly projects that benefit everyone.