Deep Earthing (Drilling) and Graphite Use for Achieving Ultra-Low Earthing Resistance in Gravelly Soils
Processes, vol.14, no.10, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 14 Issue: 10
- Publication Date: 2026
- Doi Number: 10.3390/pr14101513
- Journal Name: Processes
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex
- Keywords: deep earthing resistance, earthing resistance, graphite, gravelly soil, ground-enhancing compounds
- Istanbul University Affiliated: Yes
Abstract
This study explains how an extremely low electrical earthing resistance was achieved in challenging gravelly soil conditions. In the existing soil, a resistance of 5 ohms was measured using traditional earthing techniques. After excavating and removing the granular soil, it was replaced with fine-grained, sandy-silty clay, then compacted after moistening, reducing earthing resistance to 2.5 ohms. The goal was to achieve a resistance below 0.5 ohms, which is necessary for the precise operation of robotic welding machines. To achieve this, a hybrid strategy was employed, combining deep earthing by drilling with ground-enhancing compounds in the gravelly soil. In İzmir-Torbalı, a 40 m-deep borehole was drilled to install a copper electrode in water-saturated clay below the groundwater level. To increase the conductivity of the granular soil and ensure contact with the electrode, the borehole was filled with graphite powder. As a result, the earthing resistance reached only 0.28 ohms, proving the effectiveness of this method in high-resistance soils.