Survey & Soil Investigation

Geophysical survey

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Geophysical Survey

     Capital Survey offers a wide range of services and field experience when it comes to geophysical surveying and data interpretation for engineering purposes.Geophysical methods are routinely used to measure the engineering properties of soils and bedrock as an input to the design of foundation structures including piles.

   Surveys are conducted by trained field crews. Quality Control and Analysis is undertaken by an experienced team of geophysicists with all-over middle – east experience. We believe best quality results are obtained by utilizing state of the art equipment, applying rigorous quality control, and using robust inversion software to deliver thorough interpretations. The effectiveness of our solutions comes from applying innovation, quality, efficiency and safety on all projects.

Our range of services includes :-

MASW is a seismic method that measures the shear-wave velocity distribution, thereby can be used to measure the arrangement of overburden and bedrock. It analyzes the dispersion of surface waves (usually the fundamental-mode Rayleigh waves). Like in other seismic methods, an array of geophones is used to measure the seismic waves. The surface waves for MASW can be generated using an active source like a sledgehammer, or the ambient surface waves created by vehicles and heavy machinery can be used. The method provides the shear wave (Vs) profile in either 1D (depth) or 2D (depth and surface distance) formats. The results can be used to estimate soil and rock strength (stiffness), determine the depth and topography of bedrock (even if bedrock is below water table), map subsurface geology (lateral and vertical variations), map low velocity layers.

Crosshole Seismic (CS) and Downhole Seismic (DS) tests are performed on soil and rock sites to measure the in-place shear and compression wave velocity profiles of the soil and rock versus depth. Using these measurements, calculations can then be made of the dynamic soil and rock properties for earthquake design analyses for structures, liquefaction potential studies, site development and dynamic machine foundation designs. The parameters that can be determined include Poisson’s ratios as well as shear and Young’s moduli. In addition, the

material damping can be estimated from CS test results. The CS is a cross-hole test that requires at least two boreholes, while DS testing requires only one.

The Electrical Resistivity Tomography (ERT) method is a near-surface geophysical method that uses direct current to measure the earth’s resistivity. Electrical testing method where current is induced in the ground using two current electrodes.  The electrical potential drop is then read using two other electrodes.  There are many different electrode array configurations available, but all configurations are aimed at gathering data that can be used to estimate lateral and vertical variations in ground resistivity values.  

Capital Survey offers ERT surveys for map geologic variations including: soil lithology (e.g., clay versus gravel), presence of groundwater, fracture zones, variations in soil saturation, areas of increased salinity or, in some cases, groundwater contamination. ERT can be used to map bedrock depths and geometry; although in most geologic settings MASW or SRT are better suited for mapping top-of-bedrock.  ERT is often the best option for mapping cavities such as caves, karst and/or evaporite dissolution sinkholes.  Like seismic, the electrical method has the capacity to yield either 1D (vertical electrical sounding), 2D (profile) or 3D (volume) imaging.

Ground penetrating radar is a geophysical method that uses radar pluses to image the subsurface. It is a non- intrusive method of surveying the subsurface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables or masonry.

    Capital Survey offers Geophysical survey imaging services for Non-Destructive Testing (NDT) evaluation to locate and map subsurface features. Using Ground Penetrating Radar (GPR) uncovering the mysteries below the ground. The depth of exploration is determined by the Ground Penetrating Radar frequency, Ground makeup, soil conditions and type of target to be identified.