A 40-ton crane lowers a 30-meter vibroprobe into the ground. That probe, vibrating at 30 Hz, densifies loose granular soils at a depth of up to 25 meters. In Calgary, where glacial till overlays deep sand and gravel deposits, vibrocompaction is a go-to solution for improving bearing capacity. We use this technique to reduce settlement risk in commercial and residential projects. Before mobilizing, we always run a preliminary geotechnical CPT to map soil stratigraphy. That data tells us exactly where the probe needs to go and how much energy to apply. It's a straightforward process, but precision matters.
Vibrocompaction can achieve relative densities above 85% in Calgary's granular soils, cutting settlement risk by half.
Methodology and scope
Calgary's Bow River valley is underlain by fluvial sands and gravels that can be loose near the surface. Vibrocompaction works best in these conditions because the vibration rearranges particles into a denser state. We typically achieve relative densities above 85% after treatment. The process is fast—a single probe point takes about 20 minutes. And it's green: no cement, no additives, just mechanical densification. For projects on the city's eastern outskirts, where silt content rises, we supplement with deep soil mixing for cohesive layers. Key parameters we track include:
Technical reference image — Calgary
Local considerations
The National Building Code of Canada 2020 (NBCC 2020) considers liquefaction risk in seismic zones. Calgary sits in Seismic Hazard Zone 2, meaning moderate earthquake potential exists. Loose, saturated sands in the river valley are the main concern. Without proper vibrocompaction, those soils can lose strength during shaking. We design treatment grids based on SPT blow counts (N1,60) and vs30/" data-interlink="1">shear wave velocity profiles. Post-treatment testing verifies the target density is reached. Skipping this step leaves the structure vulnerable.
How does vibrocompaction differ from dynamic compaction?
Vibrocompaction uses a deep probe that vibrates at high frequency to densify soil from the bottom up. Dynamic compaction drops a heavy weight from a crane. Vibrocompaction reaches greater depths (up to 25 m) and works better in saturated sands.
What is the typical cost range for vibrocompaction design in Calgary?
For a standard project, design fees range from CA$2,140 to CA$7,260 depending on treatment depth, site area, and post-treatment testing scope. This covers analysis, grid design, and a final report.
Can vibrocompaction be used on clay soils?
No. Vibrocompaction only works in cohesionless soils like sand and gravel. For clay, we recommend alternative methods such as deep soil mixing or preloading.
How long does vibrocompaction treatment take on a typical site?
A single probe point takes about 20 minutes. For a 1,000 m² site, total treatment time is usually 2–3 days, including mobilization and post-treatment testing.
