Solving complex problems related to damage to structures or pavement, or the causes of landslides or other earth movements, requires characterization of pertinent aspects of the site’s surface and subsurface soil, rock, and groundwater conditions, and the geologic processes occurring on the site. Site characterization consists of the collection and analysis of information gathered through geological, geophysical, hydrological, and geotechnical site investigations. Investigations are tailored to yield the types of information needed to answer specific questions relevant to a client’s project. Generally, the surface and subsurface conditions at a site reflect a complex combination of natural factors—topographic, geologic, and climatic—as well as factors related to human activities such as grading, modification of drainage, and construction. The objectives of site characterization are to identify the distribution, composition, and subsurface geometry of the soil and rock materials, define the engineering properties of major rock and soil types, identify discontinuities such as thin clay seams that may affect slope stability or other significant factors of the site, establish existing groundwater conditions, and assess how these properties may have changed through time.
Exponent has the expertise in the full spectrum of techniques to conduct cutting-edge surface and subsurface investigations of almost any site, however challenging, in a diverse range of settings worldwide. The choice of the equipment and technique used for field exploration is frequently influenced by accessibility of a specific location on a project site, availability of equipment, and local or prior experience.
Our services include:
Acquisition and critical review of maps and reports of previous site investigations
- Analysis of topographic maps, geologic maps, and soil surveys
- Interpretation of satellite imagery and aerial photography
- Interpretation of light detection and ranging (Lidar) data and imagery, to accurately locate and depict important ground surface features
- Geologic field mapping of surface exposures of soil and rock
- Detailed field mapping of cracks, separations, and bulges in structures and pavement that potentially reflect movement of the underlying or adjacent ground
- Sampling and logging of test pits and borings, including hollow-stem auger borings, rock-core borings, sonic and percussion hammer borings, and large-diameter borings (including downhole logging) using both conventional and hillside drill rigs
- Interpretation of cone penetrometer test (CPT), in-situ vane shear testing, standard penetration testing (SPT) and geophysical data
- Identification of depth to groundwater by visual observation and monitoring via installation of piezometers
- Determination of the extent of potentially adverse soil conditions such as expansive soils or hydro-collapsible soils, including the use and interpretation of field collapse tests
- Field instrumentation and testing, including installation of slope inclinometers and collection and analysis of inclinometer data to measure depths, directions, and rates of landslide movement
Exponent’s licensed engineers and geologists have extensive experience in site characterization, including investigation of slope stability, surface fault rupture, liquefaction susceptibility, earthquake damage, ground deformation resulting from expansive or hydro-collapsible soils, flood hazards, local or regional ground subsidence, and surface and subsurface groundwater flow.