The shoreline communities along Kempenfelt Bay, from Allandale to Painswick, sit on loose, water-saturated sands deposited by glacial Lake Algonquin, while the upland subdivisions near Ardagh Bluffs rest on dense, overconsolidated till. This contrast in subsurface conditions means that two properties less than three kilometers apart in Barrie can present radically different liquefaction susceptibility profiles. For engineers working on mid-rise structures or infrastructure within the city's designated seismic screening zones, a site-specific liquefaction analysis is the only reliable way to quantify the risk of strength loss and excess pore pressure generation during the design earthquake. Our technical team executes cyclic stress ratio (CSR) versus cyclic resistance ratio (CRR) evaluations using field data obtained from SPT drilling campaigns, correlated to corrected blow counts (N1)60cs following the NCEER/NSF workshop procedures updated by Youd and Idriss.
A fines content shift from 15% to 35% can increase the CRR by up to 40%, completely changing the liquefaction classification for a Barrie site.
Process and scope
Site-specific factors
A truck-mounted CME-55 drill rig with an automatic trip hammer arrives on the Barrie site to advance the boreholes through the suspected liquefiable stratum. The crew executes the standard penetration test at 1.5-meter intervals, recording the raw blow counts that will later be corrected for energy ratio, rod length, and borehole diameter. Inaccurate hammer energy measurement is the single largest source of error in a liquefaction study; if the actual energy transfer ratio deviates from the assumed 60%, the corrected N values shift, and the entire CSR-CRR factor of safety calculation becomes unreliable. For this reason, every SPT hammer we deploy in Simcoe County is instrumented with a load cell and accelerometer to document the energy delivered to the rods. A site with a calculated factor of safety below 1.1 for a shallow sand layer demands either a redesign of the foundation system or a ground improvement program before construction proceeds.
Explanatory video
Regulatory framework
NBCC 2020 – Seismic Hazard and Site Classification, NCEER/NSF Workshop (1997/2001) – Liquefaction Resistance of Soils, ASTM D1586-18 – Standard Test Method for Standard Penetration Test (SPT), ASTM D5311/D5311M-13 – Cyclic Triaxial Test for Liquefaction Assessment, ASTM D2488-17 – Visual-Manual Description of Soil (field screening for liquefiable sands)
Related services
CPT-Based Liquefaction Screening
A piezocone penetration test provides a continuous, high-resolution profile of tip resistance and sleeve friction. This method eliminates the energy correction uncertainties inherent in SPT and is particularly effective in the stratified silty sands found near Barrie's waterfront. The raw data is processed using the Robertson (2015) soil behavior type charts, and the normalized cone resistance (qc1N) is used to compute the cyclic resistance ratio for each depth increment.
Post-Liquefaction Settlement and Lateral Spread Analysis
Beyond the binary yes/no liquefaction trigger, we quantify the expected vertical settlement and lateral displacement using the Zhang and Yoshimine volumetric strain models. For sites adjacent to creek embankments or the Lake Simcoe shoreline, a lateral spreading analysis based on the Bartlett and Youd empirical model is included to estimate horizontal ground displacement toward the free face.
Typical parameters
Frequently asked questions
What classification of soil in Barrie is most susceptible to liquefaction?
The glaciolacustrine sands mapped throughout the Barrie area, particularly the clean to slightly silty fine sands of the Kempenfelt Bay lowlands, are the most susceptible. These materials have a uniform gradation and are often fully saturated with a shallow water table. The critical zone is usually between 1.5 and 8.0 meters below grade. Soils with a fines content below 15% and a corrected SPT blow count (N1)60 below 15 are flagged for detailed cyclic stress evaluation.
How does the NBCC 2020 seismic hazard affect the liquefaction analysis for a Barrie project?
The NBCC 2020 provides the peak ground acceleration (PGA) for the 2%/50-year hazard level, which for Barrie is in a moderate seismic hazard zone. This PGA value, combined with the site-specific magnitude deaggregation, is the starting point for computing the cyclic stress ratio. The code also requires a Site Class determination based on the average shear wave velocity in the upper 30 meters (Vs30), which directly influences the amplification factors applied to the ground motion.
What is the difference between an SPT-based and a CPT-based liquefaction evaluation?
An SPT-based evaluation relies on corrected blow counts and provides a disturbed sample for visual classification. A CPT-based evaluation uses continuous cone resistance and sleeve friction data, offering a much higher vertical resolution without the energy correction complexities. CPT is faster and often preferred for large sites or for verifying SPT results in marginal soils. Both methods are calibrated against the NCEER and Robertson procedures and deliver comparable factors of safety when executed correctly.
What ground improvement options are available if the liquefaction analysis shows a risk?
If the factor of safety falls below the acceptable threshold, several remediation strategies can be designed. Vibrocompaction and stone columns densify loose sands by vibration and displacement, while compaction grouting injects a low-slump mortar to compact the soil laterally. For shallow deposits, excavation and recompaction under controlled moisture and density conditions is a direct and verifiable solution. The choice depends on the depth and thickness of the liquefiable layer and the proximity to adjacent structures.
What is the typical cost range for a liquefaction analysis in Barrie?
A complete liquefaction assessment, including one or two SPT boreholes to 15 meters depth, laboratory grain-size tests, and the seismic analysis report, typically falls in the range of CA$3,250 to CA$5,220. The final cost depends on the number of boreholes, the depth of the liquefiable stratum, and whether supplementary CPT sounding or cyclic triaxial testing is required to refine the resistance parameters.