Skills that we have acquired to support our seismic hazard assessment work include development of computer codes to conduct probabilistic hazard assessments, field mapping and characterization of seismogenic structures, and interpretation/application of actual strong motion recordings.
Our geologic staff is experienced in identifying and assessing the activity of surface or near-surface faults. Although not an issue in places like the Eastern U.S., surface faulting is often a critical issue when structures are sited in areas where fault rupture is a real possibility. Specific services that we offer include:
- Analysis of remote sensing images to identify structures that could produce surface rupture
- Surface geologic and geomorphic mapping to identify fault traces
- Geophysical surveying to characterize faults
- Age-dating of fault activity
- Evaluation of the hazard of surface rupture at a specific site
D'Appolonia has conducted fault studies in the U.S., South America, Europe, and the Middle East.
SOIL AND ROCK DYNAMICS
The dynamic behavior of soil and rock is a factor in the following:
- Liquefaction and cyclic mobility
- Dynamic slope stability
- Ground motion amplification or deamplification
D'Appolonia has extensive experience in solving liquefaction and cyclic mobility problems. Our approach involves characterizing the soil behavior under cyclic loading based on specific field and laboratory tests. Seismic slope stability is a key issue for many projects, especially pipeline and dam design in areas characterized by high seismicity. Seismic damage hazard analysis is carried out by coupling conventional seismic hazard analysis for a site and the slope response to various earthquake intensities. Amplification for certain frequencies of ground motion can occur as a result of the passage of seismic waves through a soil deposit. We assess amplification effects and have found the results are best presented to regulatory agencies when it can be demonstrated that actual records on comparable soils from equivalent earthquakes give similar results.
SOIL-STRUCTURE INTERACTION (SSI)
Surface structures can sometimes cause modifications of the response of soil to ground motion. We are accustomed to conducting SSI analyses utilizing state-of-the-practice computer codes. D'Appolonia has also conducted SSI research on behalf of the U.S. Nuclear Regulatory Commission.
EARTHQUAKE RESISTANT DESIGN
D'Appolonia is experienced in the design of structures to resist earthquake loadings. These structures include dams, lifelines, hydropower facilities, power plants, and landfills. Our experience extends to dynamic stability analyses and the design of seismic retrofits to existing structures. We are experienced in the application of seismic design criteria under AASHTO, FERC, and USNRC regulations and various building codes.