Geophysics and Dynamic Analysis of the ground
Applied geophysics methods for engineering are non-destructive procedures which allow to know the geotechnical characteristics of the ground on site, and to obtain images representing the geophysical parameters. Orbis has its own equipments to apply different techniques each one measuring one different physical parameters of the ground with multiple applications for dynamic and static calculation of soil structure interaction.
Seismic Methods. Seismic methods study the propagation of seismic waves throughout the subsurface and its mechanical properties. Processing data 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 behavior of the ground and establish the seismic zonation and site effect.
Passive seismic (ReMi). ReMi technique (Refraction Mircrotremor) 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 Soundig (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 to define the different ground layers, its resistivity and its thickness.
Induced Polarization. Is a survey method that measures the ground chargeability, that is, detects the material capacity of storing electricity. The test consist in introduce a high voltage electrical flux and to measure how the discharge process occurs. Application examples: SEV and Polarization
Ground Penetrating Radar. This electromagnetic method 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