Using geophysical characterization methods for geotechnical problems has become a critical and increasing part of geotechnical engineering. Geophysical methods and technologies support geotechnical engineers with detailed information that aid in design, planning, construction, and operation of structures on or below the earth’s surface. A geophysical survey is often the most cost-effective and useful means for obtaining subsurface geotechnical information. HGI has been applying a variety of techniques to enhance the state of knowledge of engineering and construction projects for over 18 years. Whether it is to understand concrete properties of roads, geologic materials for excavation, foundations, or hazards, geophysical mapping of electrical, seismic, or magnetic properties can provide a much greater level of confidence to your project.
A geotechnical geophysical survey is often the most cost-effective means for obtaining subsurface information.
Geophysical methods have key advantages when related to conventional geotechnical investigations. These technologies can be applied over large areas, can explore large soil volumes, are non-intrusive, and can identify material properties, material boundaries, and subsurface contrasts in space and time. Additional advantages include site accessibility and portability of geophysical equipment, enabling data acquisition in areas inaccessible by traditional geotechnical investigations such as heavily forested spaces, steep slopes, or ecologically sensitive areas. Geophysics may be used to fill in the gaps between boreholes or find subsurface features that might not be detected by a standard drilling and CPT program. Geotechnical geophysics is not a substitute for drilling, rather it complements a well-planned, cost-effective sampling program.
There are many geophysical tools available for geotechnical site investigations, including electrical resistivity, induced polarization (IP), ground penetrating radar (GPR), gravity, electromagnetic induction, magnetics and seismics. Each of these methods investigates subsurface conditions and materials to determine physical, mechanical, and chemical properties to evaluate the stability of natural and anthropogenic subsurface conditions. This information is used to design earthworks, enhance foundations, assess risks, and monitor site conditions.
- Mapping lithology
- Locating sand and gravel deposits
- Determining water depths
- Mapping bedrock topography and structure
- Identifying regions of potential weakness
- In-situ rock properties
- Mapping near-surface karstic sinkholes
- Finding clandestine air-filled cavities, tunnels
- Estimating rippability
- Mapping foundation integrity
- Investigating dam and levee integrity
- Evaluating landslide hazards
- Mapping concrete and asphalt properties
- Locating rebar and pipes