October 2, 2013

« All News

Geosyntec Staff Member Co-Authors Canadian Geotechnical Journal Article on Low-Cost ERT for Soil Monitoring

Geosyntec Consultants' Victor Damasceno, PhD, along with Dante Fratta and Peter J. Bosscher of the University of Wisconsin-Madison (UW), co-authored the Canadian Geotechnical Journal article "Development and Validation of a Low-Cost Electrical Resistivity Tomographer for Soil Process Monitoring" last summer. The paper, written as part of Victor's research dissertation at UW, presents the development and validation of a low-cost electrical resistivity tomography (ERT) system for the monitoring of process in soils.

"I designed and built an Electrical Resistivity Tomographer, both hardware and software," said Victor. "The design was based on industrial process monitoring and the reconstruction software was in part, developed based on medical imaging theories such as electrical impedance tomography." It should be noted that the entire system was built from zero. The objectives of the research included the design and construction of an imaging system with real-time data acquisition capabilities and that would successfully reconstruct the resistivity distribution within a soil sample.

The ERT generates 2D and 3D images of laboratory-scale soil samples based on electrical properties (i.e., electrical resistivity/conductivity) of the medium using numerical modeling and inverse theories. Once built and functional, the system was used to monitor processes in soils. The process presented in the paper was chemical diffusion in a sandy medium. The soil sample was setup such that a 2D scenario was evaluated, i.e., sample diameter much greater than sample height; and chemical diffusion monitored over time. Since the system is fully automated and data is acquired in real-time, Victor and his fellow researchers were able to monitor and successfully reconstruct the entire diffusion process.

Not included in the paper, but also part of Victor's research, was the use of the ERT to monitor bentonite slurry injection in sandy soils. This was done in a 3D setup and used to evaluate the slurry percolation in the sand sample. The changes in void-ratio and soil stiffness were also monitored using bender elements and included as part of the final monitoring system design. The objective of monitoring the slurry injection was to evaluate the reduction of liquefaction potential in sandy soils, and was conducted in partnership with professors from Purdue University.

"On another note, we made a duplicate of the system and sold it to Georgia Tech for Dr. Carlos Santamarina, who has also used the system in his own research activities," Victor said. The UW graduate received his PhD in civil engineering as well as his MS and BS degrees in civil engineering from the Universidade Federal de Vi_???ۡ????osa, Minas Gerais, Brasil. Victor is based in Geosyntec's Tampa office.