Geotechnical investigation in San Bernardino must address the complex interplay of alluvial fan deposits, the active San Jacinto and San Andreas fault systems, and variable groundwater conditions. Our subsurface exploration program defines soil stratigraphy, engineering properties, and seismic site class per CBC Chapter 16 and ASCE 7-22, providing the data required for foundation design, liquefaction assessment, and earthwork specifications. Fieldwork typically combines CPT (Cone Penetration Testing) for continuous profiling of tip resistance and pore pressure with SPT (Standard Penetration Testing) borings to recover disturbed samples and perform energy-corrected N-value correlations in coarse-grained alluvium.
Methodology follows ASTM International standards enforced by local building officials and Caltrans specifications for transportation projects. CPT soundings conform to ASTM D5778, delivering repeatable measurements of corrected cone resistance and friction ratio that support direct liquefaction triggering analyses and pile capacity estimations. SPT procedures adhere to ASTM D1586 with hammer energy calibration per ASTM D4633, ensuring reliable N60 values for settlement computations and bearing capacity equations. Where fine-grained soils require strength and consolidation parameters, we deploy In-Situ tools including the Flat Dilatometer Test (DMT) per ASTM D6635 and the Ménard pressuremeter test (PMT) per ASTM D4719 to obtain modulus, lateral stress, and undrained shear strength profiles. Undisturbed sampling with Shelby tubes (ASTM D1587) preserves soil fabric for laboratory triaxial and consolidation testing.
Typical San Bernardino projects range from warehouse distribution centers in the Inland Empire logistics corridors to hillside residential developments on colluvial slopes and public infrastructure along the I-215 and I-10 corridors. Alluvial basin sites frequently require field density testing (sand cone method, ASTM D1556) during grading to verify compaction of engineered fill above groundwater-sensitive zones. Liquefaction studies are mandatory for sites mapped within the Alquist-Priolo or seismic hazard zones, demanding rigorous integration of CPT and SPT data. Expansive clay evaluations follow CBC Section 1803.5.3, with laboratory swell testing guiding moisture-conditioned fill placement and foundation recommendations.
A standard investigation begins with a desktop review of USGS geologic maps and local fault databases, followed by utility clearance and field mobilization of drill rigs and CPT track units. Our geotechnical report delivers a concise site characterization with seismic design parameters (Site Class, PGA, MCE), foundation alternatives with allowable bearing pressures and expected settlements, lateral earth pressures for retaining structures, and pavement section designs based on R-value or CBR. Clients receive actionable, permit-ready documentation that reduces subsurface uncertainty, accelerates structural design, and satisfies the requirements of the City of San Bernardino Building and Safety Division.