# Geophysics

## Applied geophysiscs

Geophysical methods applied to engineering are non-destructive procedures that allow to study in situ the geotechnical behaviour of the ground, and to obtain representative images of the geometrical and dynamics properties of the terrain.

Orbis has its own equipments to apply different techniques each one measuring one different physical parameters of the ground with multiple applications for static and dynamic calculation of soil structure interaction.

Orbis Applied Geophysical Department is specialised on application of Electric Methods for geotechnical studies on photovoltaic plants (underground steel corrosion studies, grounding networks designs, geological models) and has an extensive experience in the Seismic Methods combination for the determination of the dynamic moduli, rigidity and damping degradation curves, applying this to the study of soil-structure interaction in dynamic equipments foundations (wind turbines, turbines, compressors..)

If you want to know more about our geophysical methods applied, you can visit our department website: https://orbisgeofisica.com/

## SEISMIC METHODS

Seismic methods study the propagation of seismic waves throughout the subsurface and its mechanical properties. Processing data technical advances have permitted to obtain more information with an increased reliability. These methods will no longer be limited to determine rippability and bedrock position but also can detect complex subsurface structures as debility areas, joints and weathering grades. They are also essential to know the dynamic behaviour of the ground and establish the seismic zonation and site effect.

» Passive seismic (ReMi).. ReMi technique (Refraction micro tremor) is a seismic method of determining the velocity of propagation of S waves through the ground. Ambient noise is recorded and the distribution profile of the degree of consolidation and ground consistency Vs obtained in the field that is directly related to the stiffness
Application examples.

» Seismic Refraction. The seismic refraction method studies the ground response when it propagates through it a compression wave (P wave) produced by mechanical methods on the surface. The study of the P-wave velocity allow obtaining conclusions about the geotechnical and geomechanical characteristics of the subsoil and the excavability or rippability limits of the ground studied.
Application examples.

» Seismic Reflection The Seismic reflection method is based on the refection of the seismic waves at the interfaces between the different media located at depth. The wave is generated by the appropriate energy source (hammer, explosives, mass fall, etc), and it is measured the transition time of the waves once they are reflected at the different surfaces with acoustic impedance contrast.
Application examples

## ELECTRICAL METHODS

Electrical methods have become in recent years in one of the most versatile methods. Thereby, it is ample proven its effectiveness and reliability in countless projects, such as geotechnical, hydrogeology, environmental geology, economic geology and risk analysis.

» Electrical tomography This technique provides information about the electrical properties of the subsurface from a very large number of potential difference measurements. An image is obtained in depth distribution of the subsurface materials resistivity values.
Application examples

» Vertical Electrical Sounding (V.E.S ) This electrical method is notable for its high definition in depth. A electric flux is introduced by two electrodes (A and B) and it generates a potential difference which is measured by other two electrodes (M and N). The test result allows defining the different ground layers, its resistivity and its thickness.
Application examples

» Induced Polarization Is a survey method that measures the ground chargeability, that is, detects the material capacity of electricity storing. The test consist in introduce a high voltage electrical flux and to measure how the discharge process occurs.
Application examples

## ELECTROMAGNETIC METHODS:

Ground Penetration Radar or GPR is an electromagnetic method that supports the safety of mechanical surveys, thanks to its ability to detect anomalies in natural and artificial structures with a high resolution. Auscultation of foundations and tunnels, buried pipes detection, thickness measurement (firm, layers ...) and karst voids detecting, are some of its uses that are becoming more common and requested. Application examples .

## DETECTION OF BURIED SERVICES (RADIO FREQUENCY AND GROUND PENETRATION RADAR):

We have the most popular detection systems for buried services: RADIO-FREQUENCY AND GPR. Both methods allow detection of metallic or non-metallic pipes, as well as tensioned and non-tensioned cables. Before drilling or digging on a construction site, leave doubts and avoid expensive and annoying breakdowns. We have extensive experience in urban, industrial or rural environments. Check availability and ask us for a quote for the detection of buried services!