Seismic of Refraction
The seismic method of refraction uses the seismic energy which returns to the surface after traveling through the soil on trajectories of refracted rays .
Normally used to locate refractory surfaces, which separate terrestrial stratums from different acoustic impedances (seismic velocities and densities).
The information is processed using specialized software, and the results are presented as seismograms or seismic sections.
Seismic of Reflection
The Seismic of Reflection method uses the pulses of seismic energy reflected by the geologic interface and registered on the surface. Using this technique, the running time of measurement is obtained, resulting in depth analysis of the stratum interface.
As well as in the Seismic of Reflection, the information is processed using specialized software, and the data is presented as seismograms or seismic sections.
Cross-Hole, Down-Hole e Masw Proof Tests
The Cross-Hole proof test consists in generating seismic waves in a sampling hole and its register in one or more adjacent holes. The objective of this procedure is to capture the longitudinal and transverse waves which propagate in subsurface without suffering the phenomenon of refraction and reflection, because the same ones can disguise the signs of interest. The results obtained let us calculate the modules of elasticity of the rocks, to be used on the planning of foundations in engineering projects.
The Down-Hole proof test is used to determine the variation of speed in the seismic wave in situ with the depth. In this method the traveling time of the waves between the surface and points inside the soil mass is measured.
In this study, it is necessary only a sampling hole or the use of a penetration tool for installing the sensor in the soil. As well as in the Cross-Hole, the results obtained let us calculate the modules of elasticity of the rocks, to be used on the planning of foundations in engineering projects.
The MASW is geotechnical subsurface investigation technique, that uses the register of the surface waves, through the use of special geophones, with the intention of getting information in 1D, 2D and 3D about the variation of velocity of the S wave related to the depth, in the place which is being investigated. The proof test is done quickly, without mechanical sampling and it enables the obtaining of the elasticity dynamic modules, using the S waves defined in the MASW proof test and the P waves defined through conventional refraction seismic. The results are used in projects of foundations for wind power generators and other engineering works.
It is a method constantly used in urban areas, due to its practicality during the stage of data acquisition and also to the fact that what would be just a noise in the conventional seismic can be used as a sign in the MASW proof test.