Using Electrical Resistivity Tomography (ERT) as a tool in geotechnical investigation of the substrate of a highway

Abstract

Geological and geotechnical engineering field tests, like structure drillings and dynamic (DPL, DPSH) or static probing (CPT), are considered for a fundamental source of information about soil and water environments. Since Eurocode 7 has been introduced, it has become more common to use also dilatometers (DMT) or pressure meters (PMT). Results obtained using all the mentioned tests are always of a discrete nature - information is provided in certain points in the field. However, they determine the basis for creating spatial models of geological structure and geotechnical condi- tions of a substratum. The range and number of investigations conducted (including drilling, probing and laboratory tests) influence precision, in which a geological structure is identified and thus, also affect probability of compatibility between spatial model and real geological conditions of a substratum. In the paper, results of non-invasive electrical resistivity tomography (ERT) method are presented, comprising 2-dimensional image of a soil medium resistance. Electrical resistance is a parameter that reflects diversification of a soil medium, considering its lithological aspect. In addition, when combined with drilling results, it can be used to accurate determination of boundaries between soil layers. Carrying out of ERT tests in the field during expressway construction contributed to identification of weak, low-strength soils like organic soils (peat, aggradated mud) and of soft consistency cohesive soils. These kinds of soil are the main cause for unacceptable deformations appearing in the new road engineering structure.

Signal Processing of GPR Data for Road Surveys

“…Falling Weight Deflectometer FWD pavement stiffness measurement [11][12][13] Electrical Resistivity Tomography ERT presence of voids, moisture assessment [14,15] Ground Penetrating Radar GPR structural detailing, deep defects detection, moisture/clay evaluation [16][17][18][19][20][21][22] Infrared Thermography IRT defects detection, moisture assessment [23][24][25] Terrestrial Laser Scanner TLS surface defects detection [26,27] Within the range of available NDT methods, ground penetrating radar (GPR) is nowadays acknowledged as one of the most effective and powerful in road inspections. The main advantages of this method are the high flexibility of use and reliability of the outcomes [6].…”

Application of the electrical resistivity method in assessing soil for the foundation of bridge structures: a case study from the Warsaw environs, Poland

“…Therefore recognition of the range of organic soils is crucial. It can be aided by geophysical prospection (Kowalczyk and Mieszkowski, 2011;Maślakowski et al, 2014a (Fig. 3c) and Schlumberger arrays (Fig.…”

“…The application of traditional geotechnical and geological-engineering research methods (boreholes, dynamic and static probing, etc.) supplying point data, coupled with geophysical methods (ground-penetrating radar, electrical resistivity imaging) allowing for a quasicontinuous record of physical changes in the soil medium, enables obtaining complementary results for the correct recognition of the soil-water conditions (Kowalczyk and Mieszkowski, 2011;Pierwoła et al, 2011;Maślakowski et al, 2014a;Kowalczyk et al, 2017).…”

“…2004; Kowalczyk and Mieszkowski, 2011;Comas et al, 2015;Walter et al, 2016) and at present more frequently for recognizing the extent of organic soils in the foundations of designed investments (Maślakowski et al, 2014a;Pasierb and Nawrocki, 2015). Electrical resistivity imaging (ERI) is often used in the recognition of complex geological conditions in investigations of the foundations of roads and motorways (Ganerød et al, 2006;Maślakowski et al, 2014a;Ngan-Tillard et al, 2010;Osinowo et al, 2011;Wisén et al, 2008;Kowalczyk et al, 2017).…”

“…Electrical resistivity imaging (ERI) is often used in the recognition of complex geological conditions in investigations of the foundations of roads and motorways (Ganerød et al, 2006;Maślakowski et al, 2014a;Ngan-Tillard et al, 2010;Osinowo et al, 2011;Wisén et al, 2008;Kowalczyk et al, 2017).…”