New developments in seismic zones must be evaluated to assess the potential for damage caused by an earthquake. Owners need information related to the quantifiable level of an actual or anticipated seismic performance associated with to a building subject to specified ground shaking and/or liquefiable soils. Geotechnology provides engineering services to help owners understand a site’s potential for damage caused by an earthquake.
Geotechnology’s seismic capabilities include liquefaction analysis, seismic site classification and site -specific hazard assessment. Soil profile coefficients are used to assess soil properties for differential settlement and liquefaction issues. Post-liquefaction settlement can also be determined. International Building Code (IBC) seismic classifications can be developed either from boring data or seismic shear wave velocity measurements, which provides a cost-effective site definition. Geotechnology develops shear wave velocity profiles using geophysical techniques. Geophysical surface wave methods involve developing basic models of subsurface velocity layers by analyzing the full waveforms of background vibrations. Downhole and cross hole geophysical methods involve taking direct measurements of shear wave velocities at the depth of interest. Shear wave velocities can also be used to calculate Young’s modulus, Poisson’s ratio and shear modulus. These calculations can be plotted on charts for various depth intervals. Engineering analysis and final reports may include the following:
- Evaluation of site conditions for liquefaction
- Site-specific seismic hazard assessment
- Anticipated seismic factors and coefficients in accordance with the IBC Code
- Elastic moduli/design parameters
- Ground improvement recommendations for liquefiable soil deposits
Geotechnology has provided seismic engineering services for numerous projects including power plant expansions, new casinos, and new and expanded wastewater treatment facilities. These projects have included site-specific assessments that have the opportunity to revise the IBC seismic code to a less conservative level, potentially saving the owners thousands of dollars in construction costs.