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Laboratory for Geophysical Properties of Rocks and Soils

Largo San Marcellino, 10 - 80138 NAPOLI

 
Scientific Coordinator (RADOR): 
Tel.: 081-2538377
 
 
The Laboratory for geophysical properties of rocks and soils aims at characterizing earth materials through the definition of electric, elastic and thermal properties as well as their changes as function of physico-structural variations of the investigated materials, such as porosity, fracturing, saturation degree, humidity, etc.
Many different types of experiments allow research development in several geophysical application fields, such as slope stability analysis and aquifer system characterization by establishing functional relationships between geophysical and geotechnical and hydrogeological parameters; study of soil and groundwater pollution phenomena through the definition of relationships between geophysical parameters and nature/concentration of pollutants; identification of endogenous causes of degradation of architectural structures. 
 
Equipment
  • Georesistivimeter STING R1 IP (Advanced Geosciences, Inc.)
  • Multimeter/Switch System KEITHLEY 2700-20 Channels Multiplexer card
  • Voltage generator HP 6920B
  • High performance digital Multimeter HP 34401A
  • Digital Multimeter FLUKE 8840A
  • Ultrasonic pulse generator CONTROLS E46
  • Ultrasonic Transducers with center frequency of 54 kHz and 150 kHz
  • Analog Oscilloscope HAMEG INSTRUMENTS HM 2005
  • AD Converter PICO ADC-200
  • PGW753e Precision Balance
  • Laboratoryoven for drying samples
  • Bell jar vacuum
  • Vacuum pump
  • Multielectrode geoelectrical tomography system (equipped with ECG electrodes) for micro-geophysical measurements
  • Specimens simulating architectural structures including defects
Equipment for concurrent measurement of self-potential, resistivity and P-wave velocity of a rock sample. 
 
Multielectrode geoelectrical tomography system equipped with ECG electrodes (a) for self-potential and resistivity measurements on a concrete specimen (b) including defects (c).  
 
Measurements
The available instrumentation allows to characterize the rock/soil samples or building materials through the estimation of the following physical parameters: electrical resistivity, chargeability, spontaneous potential, elastic wave velocity, temperature.
The measurements of the electrical and elastic parameters are generally performed at varying the water content, in order to retrieve the characteristic curves of the considered parameters as function of the water saturation degree or as function of the type and percentage of pollutant.
 
Fluid saturation process of samples after depressurization (a) and for capillary rise (b). 
 
Example of resistivity (a) and P-wave velocity (b) measurements. (c) Oven for drying samples during the complete saturation/drainage measurement cycle. 
 
 
(a) Variations of resistivity (r), P-wave velocity (V) and self-potential (SP) by varying the water content of a pyroclastic soil sample. (b) Electroseismic model for the estimation of porosity and saturation degree of two pyroclastic samples as function of resistivity and velocity data observed for different water contents of the considered samples.  
 
 
The micro-geophysical measurements on specimens simulating building structures are mainly realized by 2D or 3D prospecting, at the aim to study the resistivity, self-potential and P-wave velocity variations within the structure under test, as well as by infrared thermographic inspection, in order to identify temperature variations of the investigated structure surface. The definition of such variations allows to characterize, through appropriate data modeling procedures, the material endogenous degradation causes (i.e. porosity, cracking, delamination, humidity, etc) in terms of depth, geometry and nature of the anomaly sources.
 
 
Example of resistivity and Infrared Thermography data for a sample with known defects (a): 3D modeling of resistivity data (b), thermogram (c). 
 
Teaching Activity
The Geophysical Measurement Laboratory is also used for practical exercitations to students attending the courses of Applied Geophysics as well as for the development of Bachelor and Master theses in Geological Sciences and PhD theses in Earth Sciences, Environment and Resources.