A six-story apartment complex near Lady Bird Lake needed foundation design data. The contractor wanted to maximize the basement depth without overspending on shoring. We ran a series of triaxial tests on undisturbed samples extracted from three boreholes. The project required consolidated undrained (CU) tests under effective stress conditions. Results showed an effective friction angle of 31 degrees with cohesion near 2 kPa. That data drove the final mat foundation design. Without these triaxial results, the geotechnical engineer would have overestimated bearing capacity by nearly 25 percent. We also cross-checked our findings with a resistivity survey to map variability across the site. The combination of methods saved the client thousands in unnecessary excavation.
A single triaxial test failure envelope can shift a mat foundation thickness by 15 percent. Site-specific data eliminates that guesswork.