We’ve seen it too many times: a geotechnical report for a Richmond site that relies solely on index properties or pocket penetrometer readings, and the foundation design ends up overconservative on paper but underprepared for the actual strain conditions at depth. The problem isn’t the engineer’s judgment — it’s the lack of site-specific strength data under controlled drainage and confinement. A proper triaxial test on undisturbed Shelby tube samples tells you what the soil can actually handle when it’s saturated, loaded, and sheared slowly enough for pore pressures to dissipate. In a place where the ground is mostly compressible silts and clays deposited by the Fraser River, that difference translates directly into footing dimensions, excavation support costs, and long-term settlement performance. When we run a CPT test alongside the triaxial program, we get a continuous profile of tip resistance and pore pressure that helps us pick the most critical depths for sampling, so the lab program targets the layers that govern stability.
Triaxial testing doesn’t just give you a phi angle — it tells you whether the soil dilates or contracts when it fails, and that’s what determines if a foundation settles gradually or punches through.
Methodology applied in Richmond BC
Demonstration video
Critical ground factors in Richmond BC
The northern half of Richmond sits on deep Salish Sea silts with undrained shear strengths that can drop below 20 kPa in the upper 15 meters. When you combine that with a high water table — often just 0.5 to 1.5 meters below grade — and a seismic hazard classification that puts Metro Vancouver in NBCC Seismic Zone 5, you’re dealing with soils that can lose significant strength under cyclic loading. A standard penetration test might give you N-values in the 3 to 8 range, but that number alone won’t predict how the soil behaves when pore pressure builds during an earthquake. Triaxial testing with cyclic loading capability shows whether the silt liquefies or just softens, and that answer changes the entire foundation strategy. We’ve worked on Richmond projects where a single triaxial result shifted the design from spread footings to driven piles reaching the Capilano till, adding upfront cost but eliminating a long-term settlement risk that would have been far more expensive to fix later.
Our services
Every Richmond project has its own loading timeline and drainage boundary conditions, so we tailor the triaxial program accordingly. Beyond the lab work, we coordinate the field sampling and complementary testing that makes the results usable for design.
Consolidated-Undrained Triaxial with Pore Pressure Measurement
The workhorse test for Richmond's saturated silts and clays. We run multistage CU triaxial tests on 50 mm specimens, measuring pore pressure throughout shear to derive effective stress strength parameters (c' and phi') and undrained shear strength profiles. Includes backpressure saturation to B-values above 0.95 and post-shear water content verification.
Cyclic Triaxial for Liquefaction Assessment
For sites in NBCC Site Class E or F where seismic liquefaction is a concern, we run stress-controlled cyclic triaxial tests at varying cyclic stress ratios. Results feed directly into liquefaction triggering analyses using the Seed & Idriss framework, calibrated to the Richmond subsoil profile.
Frequently asked questions
What does a triaxial test cost for a typical Richmond project?
For a standard multistage CU triaxial test on a 50 mm Shelby tube sample, you’re looking at CA$2.360 to CA$4.120 depending on the number of confining stages, the need for bender elements for small-strain measurement, and whether cyclic loading is included. A full program with three specimens and reporting usually falls in the upper end of that range.
How long does triaxial testing take from sample to report?
A consolidated-undrained test on Richmond silts typically requires 10 to 14 business days. The consolidation phase alone takes 24 to 48 hours for these low-permeability soils. If the project needs results faster, we can often provide preliminary shear strength parameters within a week, with the full report following after QA/QC review.
Do we need undisturbed samples for triaxial testing, or can we use remolded?
For foundation design parameters, you want undisturbed Shelby tube samples. Remolded specimens are useful for research or for determining residual strength, but they won’t give you the in-situ structure, overconsolidation memory, or cementation effects that control real soil behavior. We coordinate directly with the drilling crew to ensure minimal sample disturbance during extraction and transport.
Is triaxial testing mandatory for Richmond building permits?
Not every permit requires triaxial data, but when the geotechnical engineer recommends deep foundations or when the site is underlain by soft silts with undrained shear strength below 40 kPa, the City of Richmond often asks for site-specific strength testing to support the design. We’ve seen it become standard practice for buildings over three storeys and for any excavation deeper than 3 meters.