The 2022 edition of the California Building Code, referencing ASCE 7, places significant emphasis on site-specific soil parameters for seismic design categories D through F — a direct concern for projects throughout Pomona’s varied alluvial terrain. The triaxial test provides the most accurate method for determining drained and undrained shear strength, something standard direct shear simply cannot replicate when pore pressure conditions matter. For geotechnical engineers working in the city’s transitional zone between the San Gabriel Mountains fan deposits and the Chino Basin, the consolidated-undrained (CU) test with pore pressure measurement becomes indispensable. We run these advanced procedures in our accredited soils laboratory, delivering the effective stress parameters — c' and φ' — that structural engineers need for IBC-compliant foundation calculations. Complementing this, a CPT test often guides the initial selection of critical depths where undisturbed sampling becomes necessary before the triaxial program begins.
The difference between a well-designed foundation and a settlement-prone one often lies in a single triaxial test on an undisturbed sample from the critical depth.
